tag:theconversation.com,2011:/africa/topics/quantum-computing-525/articlesQuantum computing – The Conversation2024-03-28T01:37:12Ztag:theconversation.com,2011:article/2264012024-03-28T01:37:12Z2024-03-28T01:37:12ZQuantum computing just got hotter: 1 degree above absolute zero<figure><img src="https://images.theconversation.com/files/584893/original/file-20240327-26-7h2dj1.JPG?ixlib=rb-1.1.0&rect=11%2C2%2C1985%2C1266&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Diraq</span></span></figcaption></figure><p>For decades, the pursuit of quantum computing has struggled with the need for extremely low temperatures, mere fractions of a degree above absolute zero (0 Kelvin or –273.15°C). That’s because the quantum phenomena that grant quantum computers their unique computational abilities can only be harnessed by isolating them from the warmth of the familiar classical world we inhabit.</p>
<p>A single quantum bit or “qubit”, the equivalent of the binary “zero or one” bit at the heart of classical computing, requires a large refrigeration apparatus to function. However, in many areas where we expect quantum computers to deliver breakthroughs – such as in designing new materials or medicines – we will need large numbers of qubits or even whole quantum computers working in parallel.</p>
<p>Quantum computers that can manage errors and self-correct, essential for reliable computations, are anticipated to be gargantuan in scale. Companies like Google, IBM and PsiQuantum are preparing for a future of entire warehouses filled with cooling systems and consuming vast amounts of power to run a single quantum computer.</p>
<p>But if quantum computers could function at even slightly higher temperatures, they could be much easier to operate – and much more widely available. In new research <a href="https://www.nature.com/articles/s41586-024-07160-2">published in Nature</a>, our team has shown a certain kind of qubit – the spins of individual electrons – can operate at temperatures around 1K, far hotter than earlier examples.</p>
<h2>The cold, hard facts</h2>
<p>Cooling systems become less efficient at lower temperatures. To make it worse, the systems we use today to control the qubits are intertwining messes of wires reminiscent of <a href="https://en.wikipedia.org/wiki/ENIAC">ENIAC</a> and other huge computers of the 1940s. These systems increase heating and create physical bottlenecks to making qubits work together.</p>
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<a href="https://theconversation.com/how-long-before-quantum-computers-can-benefit-society-thats-googles-us-5-million-question-226257">How long before quantum computers can benefit society? That's Google's US$5 million question</a>
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<p>The more qubits we try to cram in, the more difficult the problem becomes. At a certain point the wiring problem becomes insurmountable. </p>
<p>After that, the control systems need to be built into the same chips as the qubits. However, these integrated electronics use even more power – and dissipate more heat – than the big mess of wires. </p>
<h2>A warm turn</h2>
<p>Our new research may offer a way forward. We have demonstrated that a particular kind of qubit – one made with a quantum dot printed with metal electrodes on silicon, using technology much like that used in existing microchip production – can operate at temperatures around 1K.</p>
<p>This is only one degree above absolute zero, so it’s still extremely cold. However, it’s significantly warmer than previously thought possible. This breakthrough could condense the sprawling refrigeration infrastructure into a more manageable, single system. It would drastically reduce operational costs and power consumption.</p>
<p>The necessity for such technological advancements isn’t merely academic. The stakes are high in fields like drug design, where quantum computing promises to revolutionise how we understand and interact with molecular structures.</p>
<p>The research and development expenses in these industries, running into billions of dollars, underscore the potential cost savings and efficiency gains from more accessible quantum computing technologies.</p>
<h2>A slow burn</h2>
<p>“Hotter” qubits offer new possibilities, but they will also introduce new challenges in error correction and control. Higher temperatures may well mean an increase in the rate of measurement errors, which will create further difficulties in keeping the computer functional. </p>
<p>It is still early days in the development of quantum computers. Quantum computers may one day be as ubiquitous as today’s silicon chips, but the path to that future will be filled with technical hurdles. </p>
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<a href="https://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">Explainer: quantum computation and communication technology </a>
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<p>Our recent progress in operating qubits at higher temperatures is as a key step towards making the requirements of the system simpler.</p>
<p>It offers hope that quantum computing may break free from the confines of specialised labs into the broader scientific community, industry and commercial data centres.</p><img src="https://counter.theconversation.com/content/226401/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Dzurak works at Diraq. Through Diraq, he receives funding from Australian Research Council (ARC), UNSW Sydney, US Army Research Office (ARO), the US Air Force Office of Scientific Research (AFOSR) and the Australian Government, among other organisations.</span></em></p><p class="fine-print"><em><span>Andre Saraiva works at Diraq. Through Diraq, he receives funding from Australian Research Council (ARC), UNSW Sydney, US Army Research Office (ARO), the US Air Force Office of Scientific Research (AFOSR) and the Australian Government, among other organisations.</span></em></p>Quantum computers that work at slightly higher temperatures could be cheaper and more accessible.Andrew Dzurak, Scientia Professor Andrew Dzurak, CEO and Founder of Diraq, UNSW SydneyAndre Luiz Saraiva De Oliveira, Solid State Physicist, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2262572024-03-26T17:01:56Z2024-03-26T17:01:56ZHow long before quantum computers can benefit society? That’s Google’s US$5 million question<figure><img src="https://images.theconversation.com/files/583117/original/file-20240320-26-rmpub2.jpg?ixlib=rb-1.1.0&rect=5%2C0%2C3828%2C2160&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/quantum-computer-black-background-3d-render-1571871052">Bartlomiej K. Wroblewski / Shutterstock</a></span></figcaption></figure><p>Google and the XPrize Foundation have launched a competition worth US$5 million (£4 million) to develop <a href="https://blog.google/technology/research/google-gesda-and-xprize-launch-new-competition-in-quantum-applications/">real-world applications for quantum computers</a> that benefit society – by speeding up progress on one of the UN Sustainable Development Goals, for example. The principles of quantum physics suggest quantum computers could perform very fast calculations on particular problems, so this competition may expand the range of applications where they have an advantage over conventional computers.</p>
<p>In our everyday lives, the way nature works can generally be described by what we call <a href="https://en.wikipedia.org/wiki/Classical_physics#:%7E:text=Classical%20physical%20concepts%20are%20often,of%20quantum%20mechanics%20and%20relativity.">classical physics</a>. But nature behaves very differently at tiny quantum scales – below the size of an atom. </p>
<p>The race to harness quantum technology can be viewed as a new industrial revolution, progressing from devices that use the properties of classical physics to those utilising the <a href="https://www.energy.gov/science/doe-explainsquantum-mechanics#:%7E:text=Quantum%20mechanics%20is%20the%20field,%E2%80%9Cwave%2Dparticle%20duality.%E2%80%9D">weird and wonderful properties of quantum mechanics</a>. Scientists have spent decades trying to develop new technologies by harnessing these properties. </p>
<p>Given how often we are told that <a href="https://projects.research-and-innovation.ec.europa.eu/en/horizon-magazine/quantum-technologies">quantum technologies</a> will revolutionise our everyday lives, you may be surprised that we still have to search for practical applications by offering a prize. However, while there are numerous examples of success using quantum properties for enhanced precision in sensing and timing, there has been a surprising lack of progress in the development of quantum computers that outdo their classical predecessors.</p>
<p>The main bottleneck holding up this development is that the software – using <a href="https://www.nature.com/articles/npjqi201523">quantum algorithms</a> –
needs to demonstrate an advantage over computers based on classical physics. This is commonly known as <a href="https://theconversation.com/what-is-quantum-advantage-a-quantum-computing-scientist-explains-an-approaching-milestone-marking-the-arrival-of-extremely-powerful-computers-213306">“quantum advantage”</a>.</p>
<p>A crucial way quantum computing differs from classical computing is in using a property known as <a href="https://spectrum.ieee.org/what-is-quantum-entanglement">“entanglement”</a>. Classical computing <a href="https://web.stanford.edu/class/cs101/bits-bytes.html">uses “bits”</a> to represent information. These bits consist of ones and zeros, and everything a computer does comprises strings of these ones and zeros. But quantum computing allows these bits to be in a <a href="https://azure.microsoft.com/en-gb/resources/cloud-computing-dictionary/what-is-a-qubit">“superposition” of ones and zeros</a>. In other words, it is as if these ones and zeros occur simultaneously in the quantum bit, or qubit.</p>
<p>It is this property which allows computational tasks to be performed all at once. Hence the belief that quantum computing can offer a significant advantage over classical computing, as it is able to perform many computing tasks at the same time. </p>
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Read more:
<a href="https://theconversation.com/what-is-quantum-advantage-a-quantum-computing-scientist-explains-an-approaching-milestone-marking-the-arrival-of-extremely-powerful-computers-213306">What is quantum advantage? A quantum computing scientist explains an approaching milestone marking the arrival of extremely powerful computers</a>
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<h2>Notable quantum algorithms</h2>
<p>While performing many tasks simultaneously should lead to a performance increase over classical computers, putting this into practice has proven more difficult than theory would suggest. There are actually only a few notable quantum algorithms which can perform their tasks better than those using classical physics.</p>
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<img alt="Quantum chips - rendering" src="https://images.theconversation.com/files/583127/original/file-20240320-20-fnde2i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/583127/original/file-20240320-20-fnde2i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/583127/original/file-20240320-20-fnde2i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/583127/original/file-20240320-20-fnde2i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/583127/original/file-20240320-20-fnde2i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=464&fit=crop&dpr=1 754w, https://images.theconversation.com/files/583127/original/file-20240320-20-fnde2i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=464&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/583127/original/file-20240320-20-fnde2i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=464&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/futuristic-cpu-quantum-processor-global-computer-1210158169">Yurchanka Siarhei / Shutterstock</a></span>
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<p>The most notable are the <a href="https://www.st-andrews.ac.uk/physics/quvis/simulations_html5/sims/cryptography-bb84/Quantum_Cryptography.html">BB84 protocol</a>, developed in 1984, and <a href="https://www.nature.com/articles/s41598-021-95973-w">Shor’s algorithm</a>, developed in 1994, both of which use entanglement to outperform classical algorithms on particular tasks. </p>
<p>The BB84 protocol is a cryptographic protocol – a system for ensuring secure, private communication between two or more parties which is considered more secure than comparable classical algorithms.</p>
<p>Shor’s algorithm uses entanglement to demonstrate how current <a href="https://www.rand.org/pubs/commentary/2023/09/when-a-quantum-computer-is-able-to-break-our-encryption.html#:%7E:text=One%20of%20the%20most%20important,secure%20internet%20traffic%20against%20interception.">classical encryption protocols can be broken</a>, because they are based on the factorisation of very large numbers. <a href="https://ieeexplore.ieee.org/document/365700">There is also evidence</a> that it can perform certain calculations faster than similar algorithms designed for conventional computers. </p>
<p>Despite the superiority of these two algorithms over conventional ones, few advantageous quantum algorithms have followed. However, researchers have not given up trying to develop them. Currently, there are a couple of main directions in research.</p>
<h2>Potential quantum benefits</h2>
<p>The first is to use quantum mechanics to assist in what are called <a href="https://arxiv.org/abs/2312.02279">large-scale optimisation tasks</a>. Optimisation – finding the best or most effective way to solve a particular task – is vital in everyday life, from ensuring traffic flow runs effectively, to managing operational procedures in factory pipelines, to streaming services deciding what to recommend to each user. It seems clear that quantum computers could help with these problems.</p>
<p>If we could reduce the computational time required to perform the optimisation, it could save energy, reducing the carbon footprint of the many computers currently performing these tasks around the world and the data centres supporting them.</p>
<p>Another development that could offer wide-reaching benefits is to use quantum computation to simulate systems, such as combinations of atoms, that behave according to quantum mechanics. Understanding and predicting how quantum systems work in practice could, for example, lead to better drug design and medical treatments. </p>
<p>Quantum systems could also lead to improved electronic devices. As computer chips get smaller, quantum effects take hold, potentially reducing the devices’s performance. A better fundamental understanding of quantum mechanics could help avoid this.</p>
<p>While there has been significant investment in building quantum computers, there has been less focus on ensuring they will directly benefit the public. However, that now appears to be changing.</p>
<p>Whether we will all have quantum computers in our homes within the next 20 years remains doubtful. But, given the current financial commitment to making quantum computation a practical reality, it seems that society is finally in a better position to make use of them. What precise form will this take? There’s US$5 million dollars on the line to find out.</p><img src="https://counter.theconversation.com/content/226257/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Lowe does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Quantum computing has huge promise from a technical perspective, but the practical benefits are less clear.Adam Lowe, Lecturer, School of Computer Science and Digital Technologies, Aston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2244772024-03-11T12:26:13Z2024-03-11T12:26:13ZAre private conversations truly private? A cybersecurity expert explains how end-to-end encryption protects you<figure><img src="https://images.theconversation.com/files/580537/original/file-20240307-24-mrho7r.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1080%2C719&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Several popular messaging apps, including Messenger, Signal, Telegram and WhatsApp, use end-to-end encryption.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/openrightsgroup/50534017012/in/dateposted-public/"> Open Rights Group/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Imagine opening your front door wide and inviting the world to listen in on your most private conversations. Unthinkable, right? Yet, in the digital realm, people inadvertently leave doors ajar, potentially allowing hackers, tech companies, service providers and security agencies to peek into their private communications. </p>
<p>Much depends on the applications you use and the <a href="https://www.passcamp.com/blog/data-encryption-standards-what-you-need-to-know/">encryption standards</a> the apps uphold. <a href="https://www.ibm.com/topics/end-to-end-encryption">End-to-end encryption</a> is a digital safeguard for online interactions. It’s used by many of the more popular messaging apps. Understanding end-to-end encryption is crucial for maintaining privacy in people’s increasingly digital lives. </p>
<p>While end-to-end encryption effectively secures messages, it is not foolproof against all <a href="https://www.cisa.gov/topics/cyber-threats-and-advisories">cyberthreats</a> and requires users to actively manage their privacy settings. As a <a href="https://scholar.google.com/citations?hl=en&user=0ixaP0AAAAAJ&view_op=list_works&sortby=pubdate">cybersecurity researcher</a>, I believe that continuous advancements in encryption are necessary to safeguard private communications as the <a href="https://www.enzuzo.com/blog/digital-privacy-definition">digital privacy</a> landscape evolves.</p>
<h2>How end-to-end encryption works</h2>
<p>When you send a message via an app using end-to-end encryption, your app acts as a cryptographer and encodes your message with a <a href="https://www.thesslstore.com/blog/cryptographic-keys-101-what-they-are-how-they-secure-data/">cryptographic key</a>. This process transforms your message into a <a href="https://www.hypr.com/security-encyclopedia/cipher">cipher</a> – a jumble of seemingly random characters that conceal the true essence of your message. </p>
<p>This ensures that the message remains a private exchange between you and your recipient, safeguarded against unauthorized access, whether from hackers, service providers or surveillance agencies. Should any <a href="https://www.fortinet.com/resources/cyberglossary/eavesdropping">eavesdroppers</a> intercept it, they would see only gibberish and would not be able to decipher the message without the <a href="https://sensorstechforum.com/what-is-decryption-key/">decryption key</a>.</p>
<p>When the message reaches its destination, the recipient’s app uses the corresponding decryption key to unlock the message. This decryption key, securely stored on the recipient’s device, is the only key capable of deciphering the message, translating the encrypted text back into readable format.</p>
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<a href="https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing three document icons linked left to right by two arrows with key icons above the arrows" src="https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=281&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=281&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=281&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=353&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=353&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580578/original/file-20240307-23-3a9gom.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=353&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">When you send a message using end-to-end encryption, the app on your phone uses the recipient’s public key to encrypt the message. Only the recipient’s private key, stored on their phone, can decrypt the message.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Asymmetric_encryption_scheme.png">MarcT0K/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>This form of encryption is called <a href="https://ssd.eff.org/module/deep-dive-end-end-encryption-how-do-public-key-encryption-systems-work">public key, or asymmetric, cryptography</a>. Each party who communicates using this form of encryption has two encryption keys, one public and one private. You share your public key with whoever wants to communicate securely with you, and they use it to encrypt their messages to you. But that key can’t be used to decrypt their messages. Only your private key, which you do not share with anyone, can do that. </p>
<p>In practice, you don’t have to think about sharing keys. Messaging apps that use end-to-end encryption handle that behind the scenes. You and the party you are communicating securely with just have to use the same app.</p>
<h2>Who has end-to-end encryption</h2>
<p>End-to-end encryption is used by major messaging apps and services to safeguard users’ privacy. </p>
<p>Apple’s <a href="https://www.apple.com/privacy/features/">iMessage</a> integrates end-to-end encryption for messages exchanged between iMessage users, safeguarding them from external access. However, messages sent to or received from non-iMessage users such as SMS texts to or from Android phones do not benefit from this level of encryption.</p>
<p>Google has begun rolling out end-to-end encryption for <a href="https://support.google.com/messages/answer/10262381?hl=en">Google Messages</a>, the default messaging app on many Android devices. The company is aiming to modernize traditional SMS with more advanced features, including better privacy. However, this encryption is currently limited to one-on-one chats.</p>
<p><a href="https://about.fb.com/news/2023/12/default-end-to-end-encryption-on-messenger/">Facebook Messenger</a> also offers end-to-end encryption, but it is not enabled by default. Users need to start a “<a href="https://parentzone.org.uk/article/facebook-secret-conversations">Secret Conversation</a>” to encrypt their messages end to end. End-to-end encrypted chats are currently available only in the Messenger app on iOS and Android, not on Facebook chat or messenger.com.</p>
<p><a href="https://faq.whatsapp.com/490592613091019">WhatsApp</a> stands out for its robust privacy features, implementing end-to-end encryption by default for all forms of communication within the app. </p>
<p><a href="https://signal.org/">Signal</a>, often heralded by cybersecurity experts as the gold standard for secure communication, offers end-to-end encryption across all its messaging and calling features by default. Signal’s commitment to privacy is reinforced by its open-source protocol, which allows independent experts to verify its security. </p>
<p><a href="https://telegram.org/faq">Telegram</a> offers a nuanced approach to privacy. While it provides strong encryption, its standard chats do not use end-to-end encryption. For that, users must initiate “<a href="https://core.telegram.org/blackberry/secretchats">Secret Chats</a>.”</p>
<p>It’s essential to not only understand the privacy features offered by these platforms but also to <a href="https://www.telemessage.com/privacy-settings-in-mobile-messaging-apps-how-to-configure-and-which-app-protects-your-privacy-best/">manage their settings</a> to ensure the highest level of security each app offers. With varying levels of protection across services, the responsibility often falls on the user to choose messaging apps wisely and to opt for those that provide end-to-end encryption by default. </p>
<h2>Is end-to-end encryption effective?</h2>
<p>The effectiveness of end-to-end encryption in safeguarding privacy is a subject of much debate. While it significantly enhances security, no system is entirely foolproof. Skilled hackers with sufficient resources, especially those backed by security agencies, can sometimes find ways around it. </p>
<p>Additionally, end-to-end encryption does not protect against threats posed by <a href="https://www.seciron.com/blog/10-signs-that-your-mobile-device-is-compromised/">hacked devices</a> or <a href="https://usa.kaspersky.com/resource-center/preemptive-safety/phishing-prevention-tips">phishing attacks</a>, which can compromise the security of communications.</p>
<p>The coming era of <a href="https://www.scientificamerican.com/article/are-quantum-computers-about-to-break-online-privacy/">quantum computing</a> poses a potential risk to end-to-end encryption, because quantum computers could theoretically break current encryption methods, highlighting the need for continuous advancements in encryption technology. </p>
<p>Nevertheless, for the average user, end-to-end encryption offers a robust defense against most forms of digital eavesdropping and cyberthreats. As you navigate the evolving landscape of digital privacy, the question remains: What steps should you take next to ensure the continued protection of your private conversations in an increasingly interconnected world?</p><img src="https://counter.theconversation.com/content/224477/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Chataut does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>End-to-end encryption provides strong protection for keeping your communications private, but not every messaging app uses it, and even some of the ones that do don’t have it turned on by default.Robin Chataut, Assistant Professor of Cybersecurity and Computer Science, Quinnipiac UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2185952024-01-24T19:06:45Z2024-01-24T19:06:45ZAustralia may spend hundreds of millions of dollars on quantum computing research. Are we chasing a mirage?<figure><img src="https://images.theconversation.com/files/571090/original/file-20240124-19-t230yk.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3880%2C2052&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/background-pattern-vNCBkSX3Nbo">Dynamic Wang / Unsplash</a></span></figcaption></figure><p>The Australian government is going all in on quantum computing. After investing more than $100 million on “quantum technology” <a href="https://ministers.treasury.gov.au/ministers/jane-hume-2020/media-releases/111-million-investment-back-australias-quantum-technology">in 2021</a>, it is now <a href="https://www.innovationaus.com/govt-uses-secret-eoi-in-search-for-quantum-computer/">reportedly</a> considering spending up to $200 million on purchasing a “quantum computer” from a US company. </p>
<p>Is this a sensible decision? You might think so, if you read reports from <a href="https://www.zdnet.com/article/quantum-computers-eight-ways-quantum-computing-is-going-to-change-the-world/">media</a>, industry and <a href="https://www.industry.gov.au/publications/national-quantum-strategy/appendix-categories-quantum-technologies">government</a> predicting that quantum computers will revolutionise many fields of science. Two common examples given are drastically accelerating the <a href="https://spectrum.ieee.org/lithium-air-battery-quantum-computing">design of better batteries</a> and <a href="https://www.mckinsey.com/industries/life-sciences/our-insights/pharmas-digital-rx-quantum-computing-in-drug-research-and-development">drug discovery</a>. </p>
<p>Given the scale of investment, from governments around the world and also private companies, you might think quantum computers are a sure bet to reach these amazing goals. Unfortunately, in the words of US quantum computing theorist Scott Aaronson, the reality is “<a href="https://x.com/DulwichQuantum/status/1740842486262849884?s=20">much iffier</a>”.</p>
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<h2>What’s so iffy about quantum computing?</h2>
<p>In a recent <a href="https://www.pnas.org/doi/10.1073/pnas.2313269120">perspective article</a> in the Proceedings of the National Academy of Sciences, French physicist Xavier Waintal warned of weaknesses in “the quantum house of cards”. Waintal notes that “a simple task such as multiplying 3 by 5 is beyond existing quantum hardware” and that a useful quantum computer might “require an improvement by a factor of one billion” on the error rate of current devices.</p>
<p><a href="https://spectrum.ieee.org/quantum-computing-skeptics">Skeptical voices such as Waintal’s are growing louder</a> as success still seems a long way off, despite huge investments of time and effort. While companies like IBM and Google are still spending on quantum computing, China’s tech giants are <a href="https://www.reuters.com/technology/baidu-donate-quantum-computing-lab-equipment-beijing-institute-2024-01-03/">dumping their own quantum computing labs</a>.</p>
<p>It’s possible that a chain of breakthroughs could occur over the next few years, leading to useful quantum computers. We have seen other technologies, such as traditional computing chips, make huge improvements in short amounts of time. </p>
<p>However, improvements in traditional computing have resulted from massive investment over many decades. Before we can decide whether such a large investment is worth it for quantum computers, we need a clear understanding of their applications. </p>
<h2>What would quantum computers really be good for?</h2>
<p>One application that first drew attention to the idea of quantum computers (in the 1990s) is their ability to <a href="https://pubs.aip.org/aapt/ajp/article-abstract/73/6/521/1041912/Shor-s-factoring-algorithm-and-modern-cryptography?redirectedFrom=fulltext">break some kinds of encryption</a> commonly used to store and transmit data. However, <a href="https://link.springer.com/chapter/10.1007/978-3-031-33386-6_10">new encryption methods</a> have since been developed that would be safe from quantum computers.</p>
<p>Now attention has moved to the potential ability of quantum computers to solve problems in biology and chemistry, such as drug discovery and battery design. The idea is that biology and chemistry are governed by <a href="https://www.ted.com/talks/tim_duignan_why_simple_salt_water_is_so_much_more_than_it_seems">the same laws of quantum mechanics</a> that control the workings of quantum computers.</p>
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<a href="https://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">Explainer: quantum computation and communication technology </a>
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<p>This argument seems plausible, but it has some problems. One is that, although chemistry and biology do follow the laws of quantum mechanics, in many cases their behaviours are almost indistinguishable from non-quantum ones. </p>
<p>In fact, there is <a href="https://arxiv.org/abs/2208.02199">no guarantee</a> that quantum computers will be able to outperform current computers when applied to problems in biology and chemistry. </p>
<p>It’s possible that once we have built a quantum computer we will be able to find ways to make it solve problems in biology and chemistry faster than a normal computer, but it’s far from guaranteed.</p>
<h2>Can AI outdo quantum computers?</h2>
<p>Quantum computing advocates are not alone in wanting to better simulate chemistry and biology. Many other scientists are working on this problem as well.</p>
<p>For example, quantum chemistry and molecular simulation are two very active research fields. These scientists are making rapid progress on solving many of the problems that supposedly justify the development of quantum computers. </p>
<p>Most excitingly, these fields are taking advantage of recent developments in artificial intelligence to massively improve the scale and accuracy with which they can simulate biology and chemistry. In <a href="https://arxiv.org/abs/2401.00096">one recent example</a>, researchers trained an AI algorithm on a huge dataset and used it to study a large range of chemical and biological systems with impressive accuracy and speed.</p>
<h2>Quantum alternatives</h2>
<p>“Useful” quantum computers are still some distance away, if they ever eventuate. And even if they are built, they may not be as useful as their advocates hope. </p>
<p>So while it’s reasonable for our government to invest in quantum computing research, we should be realistic about what we hope to get out of it. And we shouldn’t neglect other avenues in the quest to understand chemistry and biology at the most fundamental levels.</p>
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<a href="https://theconversation.com/australia-has-a-national-quantum-strategy-what-does-that-mean-205232">Australia has a National Quantum Strategy. What does that mean?</a>
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<p>Just as a smart investment strategy is to diversity, we should do the same with our research funding, backing many different potentially exciting technologies. We should be humble about our ability to know which research directions are the most promising, as the future is incredibly hard to predict. If it wasn’t, we wouldn’t need a quantum computer in the first place.</p><img src="https://counter.theconversation.com/content/218595/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy Duignan receives funding from Australian Research Council. </span></em></p>Quantum computers are proving extremely difficult to build, and there is no guarantee they will live up to their designers’ hopes.Timothy Duignan, Lecturer, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2133062023-11-17T13:29:43Z2023-11-17T13:29:43ZWhat is quantum advantage? A quantum computing scientist explains an approaching milestone marking the arrival of extremely powerful computers<figure><img src="https://images.theconversation.com/files/559476/original/file-20231114-21-dv3rca.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5731%2C3829&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">IBM's quantum computer got President Joe Biden's attention.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/president-joe-biden-looks-at-quantum-computer-as-he-tours-news-photo/1243772280">Mandel Ngan/AFP via Getty Images</a></span></figcaption></figure><p>Quantum advantage is the milestone the field of quantum computing is fervently working toward, where a quantum computer can solve problems that are beyond the reach of the most powerful non-quantum, or classical, computers. </p>
<p>Quantum refers to the scale of atoms and molecules where the laws of physics as we experience them break down and a different, counterintuitive set of laws apply. Quantum computers take advantage of these strange behaviors to solve problems.</p>
<p>There are some types of problems that are <a href="https://theconversation.com/limits-to-computing-a-computer-scientist-explains-why-even-in-the-age-of-ai-some-problems-are-just-too-difficult-191930">impractical for classical computers to solve</a>, such as cracking state-of-the-art encryption algorithms. Research in recent decades has shown that quantum computers have the potential to solve some of these problems. If a quantum computer can be built that actually does solve one of these problems, it will have demonstrated quantum advantage.</p>
<p>I am <a href="https://scholar.google.com/citations?user=2J2t64gAAAAJ&hl=en">a physicist</a> who studies quantum information processing and the control of quantum systems. I believe that this frontier of scientific and technological innovation not only promises groundbreaking advances in computation but also represents a broader surge in quantum technology, including significant advancements in quantum cryptography and quantum sensing.</p>
<h2>The source of quantum computing’s power</h2>
<p>Central to quantum computing is the quantum bit, or <a href="https://quantumatlas.umd.edu/entry/qubit/">qubit</a>. Unlike classical bits, which can only be in states of 0 or 1, a qubit can be in any state that is some combination of 0 and 1. This state of neither just 1 or just 0 is known as a <a href="https://quantumatlas.umd.edu/entry/superposition/">quantum superposition</a>. With every additional qubit, the number of states that can be represented by the qubits doubles. </p>
<p>This property is often mistaken for the source of the power of quantum computing. Instead, it comes down to an intricate interplay of superposition, <a href="https://encyclopedia2.thefreedictionary.com/Quantum+Interference">interference</a> and <a href="https://theconversation.com/nobel-winning-quantum-weirdness-undergirds-an-emerging-high-tech-industry-promising-better-ways-of-encrypting-communications-and-imaging-your-body-191929">entanglement</a>.</p>
<p>Interference involves manipulating qubits so that their states combine constructively during computations to amplify correct solutions and destructively to suppress the wrong answers. Constructive interference is what happens when the peaks of two waves – like sound waves or ocean waves – combine to create a higher peak. Destructive interference is what happens when a wave peak and a wave trough combine and cancel each other out. Quantum algorithms, which are few and difficult to devise, set up a sequence of interference patterns that yield the correct answer to a problem.</p>
<p>Entanglement establishes a uniquely quantum correlation between qubits: The state of one cannot be described independently of the others, no matter how far apart the qubits are. This is what Albert Einstein famously dismissed as “spooky action at a distance.” Entanglement’s collective behavior, orchestrated through a quantum computer, enables computational speed-ups that are beyond the reach of classical computers.</p>
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<figcaption><span class="caption">The ones and zeros – and everything in between – of quantum computing.</span></figcaption>
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<h2>Applications of quantum computing</h2>
<p>Quantum computing has a range of potential uses where it can outperform classical computers. In cryptography, quantum computers pose both an opportunity and a challenge. Most famously, they have the <a href="https://theconversation.com/is-quantum-computing-a-cybersecurity-threat-107411">potential to decipher current encryption algorithms</a>, such as the widely used <a href="https://www.britannica.com/topic/RSA-encryption">RSA scheme</a>. </p>
<p>One consequence of this is that today’s encryption protocols need to be reengineered to be resistant to future quantum attacks. This recognition has led to the burgeoning field of <a href="https://www.nist.gov/programs-projects/post-quantum-cryptography">post-quantum cryptography</a>. After a long process, the National Institute of Standards and Technology recently selected four quantum-resistant algorithms and has begun the process of readying them so that organizations around the world can use them in their encryption technology.</p>
<p>In addition, quantum computing can dramatically speed up quantum simulation: the ability to predict the outcome of experiments operating in the quantum realm. Famed physicist Richard Feynman <a href="https://doi.org/10.1007/BF02650179">envisioned this possibility</a> more than 40 years ago. Quantum simulation offers the potential for considerable advancements in chemistry and materials science, aiding in areas such as the intricate modeling of molecular structures for drug discovery and enabling the discovery or creation of materials with novel properties. </p>
<p>Another use of quantum information technology is <a href="https://doi.org/10.1103/RevModPhys.89.035002">quantum sensing</a>: detecting and measuring physical properties like electromagnetic energy, gravity, pressure and temperature with greater sensitivity and precision than non-quantum instruments. Quantum sensing has myriad applications in fields such as <a href="https://www.azoquantum.com/Article.aspx?ArticleID=444">environmental monitoring</a>, <a href="https://doi.org/10.1038/s41586-021-04315-3">geological exploration</a>, <a href="https://doi.org/10.1038/s42254-023-00558-3">medical imaging</a> and <a href="https://www.defenseone.com/ideas/2022/06/quantum-sensorsunlike-quantum-computersare-already-here/368634/">surveillance</a>.</p>
<p>Initiatives such as the development of a quantum internet that interconnects quantum computers are crucial steps toward bridging the quantum and classical computing worlds. This network could be secured using quantum cryptographic protocols such as quantum key distribution, which enables ultra-secure communication channels that are protected against computational attacks – including those using quantum computers.</p>
<p>Despite a growing application suite for quantum computing, developing new algorithms that make full use of the quantum advantage – in particular <a href="https://journals.aps.org/prxquantum/pdf/10.1103/PRXQuantum.3.030101">in machine learning</a> – remains a critical area of ongoing research.</p>
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<span class="caption">A prototype quantum sensor developed by MIT researchers can detect any frequency of electromagnetic waves.</span>
<span class="attribution"><a class="source" href="https://news.mit.edu/2022/quantum-sensor-frequency-0621">Guoqing Wang</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<h2>Staying coherent and overcoming errors</h2>
<p>The quantum computing field faces significant hurdles in hardware and software development. Quantum computers are highly sensitive to any unintentional interactions with their environments. This leads to the phenomenon of decoherence, where qubits rapidly degrade to the 0 or 1 states of classical bits. </p>
<p>Building large-scale quantum computing systems capable of delivering on the promise of quantum speed-ups requires overcoming decoherence. The key is developing effective methods of suppressing and correcting quantum errors, <a href="http://www.cambridge.org/9780521897877">an area my own research is focused on</a>.</p>
<p>In navigating these challenges, numerous quantum hardware and software startups have emerged alongside well-established technology industry players like Google and IBM. This industry interest, combined with significant investment from governments worldwide, underscores a collective recognition of quantum technology’s transformative potential. These initiatives foster a rich ecosystem where academia and industry collaborate, accelerating progress in the field.</p>
<h2>Quantum advantage coming into view</h2>
<p>Quantum computing may one day be as disruptive as the arrival of <a href="https://memberservices.theconversation.com/newsletters/?nl=ai">generative AI</a>. Currently, the development of quantum computing technology is at a crucial juncture. On the one hand, the field has already shown early signs of having achieved a narrowly specialized quantum advantage. <a href="https://www.nature.com/articles/s41586-019-1666-5">Researchers at Google</a> and later a <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.180501">team of researchers in China</a> demonstrated quantum advantage <a href="https://doi.org/10.1038/s41534-023-00703-x">for generating a list of random numbers</a> with certain properties. My research team demonstrated a quantum speed-up <a href="https://doi.org/10.1103/PhysRevLett.130.210602">for a random number guessing game</a>.</p>
<p>On the other hand, there is a tangible risk of entering a “quantum winter,” a period of reduced investment if practical results fail to materialize in the near term.</p>
<p>While the technology industry is working to deliver quantum advantage in products and services in the near term, academic research remains focused on investigating the fundamental principles underpinning this new science and technology. This ongoing basic research, fueled by enthusiastic cadres of new and bright students of the type I encounter almost every day, ensures that the field will continue to progress.</p><img src="https://counter.theconversation.com/content/213306/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Lidar receives funding from the NSF, DARPA, ARO, and DOE.</span></em></p>Several companies have made quantum computers, but these early models have yet to demonstrate quantum advantage: the ability to outstrip ordinary supercomputers.Daniel Lidar, Professor of Electrical Engineering, Chemistry, and Physics & Astronomy, University of Southern CaliforniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2158042023-10-19T04:59:00Z2023-10-19T04:59:00ZQuantum computers in 2023: how they work, what they do, and where they’re heading<figure><img src="https://images.theconversation.com/files/554450/original/file-20231018-29-xrpphz.jpg?ixlib=rb-1.1.0&rect=17%2C43%2C5757%2C3800&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A complex cooling rig is needed to maintain the ultracold working temperatures required by a superconducting quantum computer.</span> <span class="attribution"><a class="source" href="https://newsroom.ibm.com/media-quantum-innovation">IBM</a></span></figcaption></figure><p>In June, an IBM computing executive claimed <a href="https://www.nytimes.com/2023/06/14/science/ibm-quantum-computing.html">quantum computers were entering the “utility” phase</a>, in which high-tech experimental devices become useful. In September, Australia’s Chief Scientist Cathy Foley went so far as to declare “<a href="https://www.chiefscientist.gov.au/news-and-media/its-time-australia-leverage-our-resources-and-tech-skills-prosper-new-economy">the dawn of the quantum era</a>”. </p>
<p>This week, Australian physicist <a href="https://www.abc.net.au/news/science/2023-10-16/prime-minister-science-prize-michelle-simmons-quantum-physics/102979096">Michelle Simmons won the nation’s top science award</a> for her work on developing silicon-based quantum computers.</p>
<p>Obviously, quantum computers are having a moment. But – to step back a little – what exactly <em>are</em> they? </p>
<h2>What is a quantum computer?</h2>
<p>One way to think about computers is in terms of the kinds of numbers they work with.</p>
<p>The digital computers we use every day rely on whole numbers (or <em>integers</em>), representing information as strings of zeroes and ones which they rearrange according to complicated rules. There are also analogue computers, which represent information as continuously varying numbers (or <em>real numbers</em>), manipulated via electrical circuits or spinning rotors or moving fluids.</p>
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Read more:
<a href="https://theconversation.com/theres-a-way-to-turn-almost-any-object-into-a-computer-and-it-could-cause-shockwaves-in-ai-62235">There's a way to turn almost any object into a computer – and it could cause shockwaves in AI</a>
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<p>In the 16th century, the Italian mathematician Girolamo Cardano invented another kind of number called <em>complex numbers</em> to solve seemingly impossible tasks such as finding the square root of a negative number. In the 20th century, with the advent of quantum physics, it turned out complex numbers also naturally describe the fine details of light and matter.</p>
<p>In the 1990s, physics and computer science collided when it was discovered that some problems could be solved much faster with algorithms that work directly with complex numbers as encoded in quantum physics. </p>
<p>The next logical step was to build devices that work with light and matter to do those calculations for us automatically. This was the birth of quantum computing.</p>
<h2>Why does quantum computing matter?</h2>
<p>We usually think of the things our computers do in terms that mean something to us — balance my spreadsheet, transmit my live video, find my ride to the airport. However, all of these are ultimately computational problems, phrased in mathematical language. </p>
<p>As quantum computing is still a nascent field, most of the problems we know quantum computers will solve are phrased in abstract mathematics. Some of these will have “real world” applications we can’t yet foresee, but others will find a more immediate impact.</p>
<p>One early application will be cryptography. Quantum computers will be able to crack today’s internet encryption algorithms, so we will need quantum-resistant cryptographic technology. Provably secure cryptography and a fully quantum internet would use quantum computing technology.</p>
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<img alt="A microscopic view of a square, iridescent computer chip against an orange background." src="https://images.theconversation.com/files/554626/original/file-20231018-19-68uhls.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554626/original/file-20231018-19-68uhls.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554626/original/file-20231018-19-68uhls.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554626/original/file-20231018-19-68uhls.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554626/original/file-20231018-19-68uhls.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=496&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554626/original/file-20231018-19-68uhls.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=496&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554626/original/file-20231018-19-68uhls.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=496&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Google has claimed its Sycamore quantum processor can outperform classical computers at certain tasks.</span>
<span class="attribution"><span class="source">Google</span></span>
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<p>In materials science, quantum computers will be able to simulate molecular structures at the atomic scale, making it faster and easier to discover new and interesting materials. This may have significant applications in batteries, pharmaceuticals, fertilisers and other chemistry-based domains.</p>
<p>Quantum computers will also speed up many difficult optimisation problems, where we want to find the “best” way to do something. This will allow us to tackle larger-scale problems in areas such as logistics, finance, and weather forecasting.</p>
<p>Machine learning is another area where quantum computers may accelerate progress. This could happen indirectly, by speeding up subroutines in digital computers, or directly if quantum computers can be reimagined as learning machines.</p>
<h2>What is the current landscape?</h2>
<p>In 2023, quantum computing is moving out of the basement laboratories of university physics departments and into industrial research and development facilities. The move is backed by the chequebooks of multinational corporations and venture capitalists. </p>
<p>Contemporary quantum computing prototypes – built by <a href="https://www.ibm.com/quantum">IBM</a>, <a href="https://quantumai.google/">Google</a>, <a href="https://ionq.com/">IonQ</a>, <a href="https://www.rigetti.com/">Rigetti</a> and others – are still some way from perfection. </p>
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<a href="https://theconversation.com/error-correcting-the-things-that-go-wrong-at-the-quantum-computing-scale-84846">Error correcting the things that go wrong at the quantum computing scale</a>
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<p>Today’s machines are of modest size and susceptible to errors, in what has been called the “<a href="https://thequantuminsider.com/2023/03/13/what-is-nisq-quantum-computing/">noisy intermediate-scale quantum</a>” phase of development. The delicate nature of tiny quantum systems means they are prone to many sources of error, and correcting these errors is a major technical hurdle.</p>
<p>The holy grail is a large-scale quantum computer which can correct its own errors. A whole ecosystem of research factions and commercial enterprises are pursuing this goal via diverse technological approaches. </p>
<h2>Superconductors, ions, silicon, photons</h2>
<p>The current leading approach uses loops of electric current inside superconducting circuits to store and manipulate information. This is the technology adopted by <a href="https://quantumai.google/hardware">Google</a>, <a href="https://www.ibm.com/topics/quantum-computing">IBM</a>, <a href="https://www.rigetti.com/what-we-build">Rigetti</a> and others. </p>
<p>Another method, the “trapped ion” technology, works with groups of electrically charged atomic particles, using the inherent stability of the particles to reduce errors. This approach has been spearheaded by <a href="https://ionq.com/technology">IonQ</a> and <a href="https://www.honeywell.com/us/en/company/quantum">Honeywell</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration showing glowing dots and patterns of light." src="https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=519&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=519&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=519&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=653&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=653&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554627/original/file-20231018-29-hte4r6.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=653&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">An artist’s impression of a semiconductor-based quantum computer.</span>
<span class="attribution"><a class="source" href="https://www.sqc.com.au">Silicon Quantum Computing</a></span>
</figcaption>
</figure>
<p>A third route of exploration is to confine electrons within tiny particles of semiconductor material, which could then be melded into the well-established silicon technology of classical computing. <a href="https://sqc.com.au/">Silicon Quantum Computing</a> is pursuing this angle.</p>
<p>Yet another direction is to use individual particles of light (photons), which can be manipulated with high fidelity. A company called PsiQuantum is designing <a href="https://www.nature.com/articles/s41467-023-36493-1">intricate “guided light” circuits</a> to perform quantum computations. </p>
<p>There is no clear winner yet from among these technologies, and it may well be a hybrid approach that ultimately prevails.</p>
<h2>Where will the quantum future take us?</h2>
<p>Attempting to forecast the future of quantum computing today is akin to predicting flying cars and ending up with cameras in our phones instead. Nevertheless, there are a few milestones that many researchers would agree are likely to be reached in the next decade.</p>
<p>Better error correction is a big one. We expect to see a transition from the era of noisy devices to small devices that can sustain computation through active error correction.</p>
<p>Another is the advent of post-quantum cryptography. This means the establishment and adoption of cryptographic standards that can’t easily be broken by quantum computers.</p>
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<a href="https://theconversation.com/quantum-computers-threaten-our-whole-cybersecurity-infrastructure-heres-how-scientists-can-bulletproof-it-196065">Quantum computers threaten our whole cybersecurity infrastructure: here's how scientists can bulletproof it</a>
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<p>Commercial spin-offs of technology such as quantum sensing are also on the horizon.</p>
<p>The demonstration of a genuine “quantum advantage” will also be a likely development. This means a compelling application where a quantum device is unarguably superior to the digital alternative.</p>
<p>And a stretch goal for the coming decade is the creation of a large-scale quantum computer free of errors (with active error correction). </p>
<p>When this has been achieved, we can be confident the 21st century will be the “quantum era”.</p><img src="https://counter.theconversation.com/content/215804/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Ferrie receives funding from the Australian Research Council. He is a co-founder of quantum startup Eigensystems. </span></em></p>After decades of hype, quantum computers are on the verge of becoming useful. Here’s a refresher on why they’re such a big dealChristopher Ferrie, Senior Lecturer, UTS Chancellor's Postdoctoral Research and ARC DECRA Fellow, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2079742023-07-05T12:23:21Z2023-07-05T12:23:21ZHow splitting sound might lead to a new kind of quantum computer<p>When you turn on a lamp to brighten a room, you are experiencing light energy transmitted as photons, which are small, discrete quantum packets of energy. These photons must obey the sometimes strange laws of quantum mechanics, which, for instance, dictate that photons are indivisible, but at the same time, allow a photon <a href="https://www.cambridge.org/highereducation/books/introduction-to-quantum-mechanics/990799CA07A83FC5312402AF6860311E#overview">to be in two places at once</a>. </p>
<p>Similar to the photons that make up beams of light, indivisible quantum particles <a href="https://news.mit.edu/2010/explained-phonons-0706">called phonons</a> make up a beam of sound. These particles emerge from the collective motion of quadrillions of atoms, much as a “stadium wave” in a sports arena is due to the motion of thousands of individual fans. When you listen to a song, you’re hearing a stream of these very small quantum particles.</p>
<p>Originally conceived to <a href="https://www.wiley.com/en-us/Introduction+to+Solid+State+Physics%2C+8th+Edition-p-9780471415268">explain the heat capacities of solids</a>, phonons are predicted to obey the same rules of quantum mechanics as photons. The technology to generate and detect individual phonons has, however, lagged behind that for photons. </p>
<p>That technology is only now being developed, in part by <a href="https://clelandlab.uchicago.edu/">my research group</a> at the Pritzker School of Molecular Engineering at the University of Chicago. <a href="https://scholar.google.com/citations?user=uE04v0gAAAAJ&hl=en&oi=ao">We are exploring</a> the fundamental quantum properties of sound by splitting phonons in half and entangling them together.</p>
<p>My group’s fundamental research on phonons may one day allow researchers to build a new type of quantum computer, called a mechanical quantum computer.</p>
<h2>Splitting sound with ‘bad’ mirrors</h2>
<p>To explore the quantum properties of phonons, our team uses acoustic mirrors, which can direct beams of sound. Our latest experiments, published in <a href="https://doi.org/10.1126/science.adg8715">a recent issue of Science</a>, however, involve “bad” mirrors, called beam splitters, that reflect about half the sound sent toward them and let the other half through. Our team decided to explore what happens when we direct a phonon at a beam splitter. </p>
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<span class="caption">A beam splitter for phonons – the phonon enters a superposition state where it is both reflected and transmitted until it is detected.</span>
<span class="attribution"><span class="source">A.N. Cleland</span></span>
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<p>As a phonon is indivisible; it cannot be split. Instead, after interacting with the beam splitter, the phonon ends up in what is called a “<a href="https://scienceexchange.caltech.edu/topics/quantum-science-explained/quantum-superposition">superposition state</a>.” In this state the phonon is, somewhat paradoxically, both reflected and transmitted, and you’re equally likely to detect the phonon in either state. If you intervene and detect the phonon, half the time you will measure that it was reflected and half the time that it was transmitted; in a sense, the state is <a href="https://doi.org/10.1119/1.3243279">selected at random</a> by the detector. Absent the detection process, the phonon will remain in the superposition state of being both transmitted and reflected. </p>
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<figcaption><span class="caption">A brief Ted-Ed explainer on superposition, which happens when particles can exist in multiple places at once.</span></figcaption>
</figure>
<p>This superposition effect was observed many years ago with photons. Our results indicate that phonons have the same property. </p>
<h2>Entangled phonons</h2>
<p>After demonstrating that phonons can go into quantum superpositions just as photons do, my team asked <a href="https://doi.org/10.1126/science.adg8715">a more complex question</a>. We wanted to know what would happen if we sent two identical phonons into the beam splitter, one from each direction. </p>
<p>It turns out that each phonon will go into a similar superposition state of half-transmitted and half-reflected. But because of the physics of the beam splitter, if we time the phonons precisely, they will quantum-mechanically interfere with one another. What emerges is actually a superposition state of two phonons going one way and two phonons going the other – the two phonons are thus <a href="https://scienceexchange.caltech.edu/topics/quantum-science-explained/entanglement">quantum-mechanically entangled</a>. </p>
<p>In quantum entanglement, each phonon is in a superposition of reflected and transmitted, but the two phonons are locked together. This means detecting one phonon as having been transmitted or reflected forces the other phonon to be in the same state.</p>
<p>So, if you detect, you’ll always detect two phonons, going one way or the other, never one phonon going each way. This same effect for light, the combination of superposition and interference of two photons, is called the <a href="https://doi.org/10.1103/PhysRevLett.59.2044">Hong-Ou-Mandel effect</a>, after the three physicists who first predicted and observed it in 1987. Now, my group has demonstrated this effect with sound. </p>
<h2>The future of quantum computing</h2>
<p>These results suggest that it may now be possible to build a mechanical quantum computer using phonons. There are continuing efforts to build <a href="https://news.mit.edu/2020/explained-quantum-engineering-1210">optical quantum computers</a> that require only the emission, detection and interference of single photons. These are in parallel with efforts to build electrical quantum computers, which through the use of large numbers of entangled particles promise an exponential speedup for certain problems, such as factoring large numbers or simulating quantum systems.</p>
<p>A quantum computer using phonons could be very compact and self-contained, built entirely on a chip similar to that of a laptop computer’s processor. Its small size could make it easier to implement and use, if researchers can further expand and improve phonon-based technologies.</p>
<p>My group’s <a href="https://doi.org/10.1126/science.adg8715">experiments with phonons</a> use qubits – the same technology that powers electronic quantum computers – which means that as the technology for phonons catches up, there’s the potential to integrate phonon-based computers with electronic quantum computers. Doing so could yield new, potentially unique computational abilities.</p><img src="https://counter.theconversation.com/content/207974/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew N. Cleland receives funding from various US federal funding agencies. He is a fellow of the American Physical Society (APS) and the American Association for the Advancement of Science. He is currently Past Chair of the Division of Quantum Information of the APS, and in 2023 held a Fulbright Distinguished Chair. He is a founder and a board member of Spectradyne LLC, a startup company based in Los Angeles that is commercializing electrical and optical detection of nanoparticles in fluids.</span></em></p>Scientists show they can create quantum superpositions of sound particles, pointing to the potential for mechanical quantum computers.Andrew N. Cleland, Professor of Molecular Engineering Innovation and Enterprise, University of Chicago Pritzker School of Molecular EngineeringLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2061772023-05-25T20:00:36Z2023-05-25T20:00:36ZFrom self-driving cars to military surveillance: quantum computing can help secure the future of AI systems<figure><img src="https://images.theconversation.com/files/528182/original/file-20230525-23-bqxfsg.jpeg?ixlib=rb-1.1.0&rect=8%2C62%2C5982%2C3925&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Artificial intelligence algorithms are quickly becoming a part of everyday life. Many systems that require strong security are either already underpinned by machine learning or soon will be. These systems include facial recognition, banking, military targeting applications, and robots and autonomous vehicles, to name a few.</p>
<p>This raises an important question: how secure are these machine learning algorithms against malicious attacks? </p>
<p>In an article <a href="https://www.nature.com/articles/s42256-023-00661-1">published today</a> in Nature Machine Intelligence, my colleagues at the University of Melbourne and I discuss a potential solution to the vulnerability of machine learning models.</p>
<p>We propose that the integration of quantum computing in these models could yield new algorithms with strong resilience against adversarial attacks. </p>
<h2>The dangers of data manipulation attacks</h2>
<p>Machine learning algorithms can be remarkably accurate and efficient for many tasks. They are particularly useful for classifying and identifying image features. However, they’re also highly vulnerable to data manipulation attacks, which can pose serious security risks. </p>
<p>Data manipulation attacks – which involve the very subtle manipulation of image data – can be launched in several ways. An attack may be launched by mixing corrupt data into a training dataset used to train an algorithm, leading it to learn things it shouldn’t.</p>
<p>Manipulated data can also be injected during the testing phase (after training is complete), in cases where the AI system continues to train the underlying algorithms while in use.</p>
<p>People can even carry out such attacks from the physical world. Someone could put a sticker on a stop sign to <a href="https://towardsdatascience.com/poisoning-attacks-on-machine-learning-1ff247c254db">fool a self-driving car’s</a> AI into identifying it as a speed-limit sign. Or, on the front lines, troops might wear uniforms that can fool AI-based drones into identifying them as landscape features.</p>
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Read more:
<a href="https://theconversation.com/ai-to-z-all-the-terms-you-need-to-know-to-keep-up-in-the-ai-hype-age-203917">AI to Z: all the terms you need to know to keep up in the AI hype age</a>
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<p>Either way, the consequences of data manipulation attacks can be severe. For example, if a self-driving car uses a machine learning algorithm that has been compromised, it may incorrectly predict there are no humans on the road – when there are.</p>
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<span class="caption">In this example you can see an algorithm that correctly identifies humans based on an image input. However, when a few pixels are changed in an adversarial attack, the algorithm can no longer identify the humans.</span>
<span class="attribution"><a class="source" href="https://arxiv.org/abs/1704.05712">Jan Hendrik Metzen et. al.</a>, <span class="license">Author provided</span></span>
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<h2>How quantum computing can help</h2>
<p>In our article, we describe how integrating quantum computing with machine learning could give rise to secure algorithms called quantum machine learning models. </p>
<p>These algorithms are carefully designed to exploit special quantum properties that would allow them to find specific patterns in image data that aren’t easily manipulated. The result would be resilient algorithms that are safe against even powerful attacks. They also wouldn’t require the expensive “<a href="https://towardsdatascience.com/what-is-adversarial-machine-learning-dbe7110433d6">adversarial training</a>” currently used to teach algorithms how to resist such attacks.</p>
<p>Beyond this, quantum machine learning could allow for faster algorithmic training and more accuracy in learning features.</p>
<h2>So how would it work?</h2>
<p>Today’s classical computers work by storing and processing information as “bits”, or binary digits, the smallest unit of data a computer can process. In classical computers, which follow the laws of classical physics, bits are represented as binary numbers – specifically 0s and 1s.</p>
<p>Quantum computing, on the other hand, follows principles used in quantum physics. Information in quantum computers is stored and processed as qubits (quantum bits) which can exist as 0, 1, or a combination of both at once. A quantum system that exists in multiple states at once is said to be in a superposition state. Quantum computers can be used to design clever algorithms that exploit this property.</p>
<p>However, while there are significant potential benefits in using quantum computing to secure machine learning models, it could also be a double-edged sword.</p>
<p>On one hand, quantum machine learning models will provide critical security for many sensitive applications. On the other, quantum computers could be used to generate powerful adversarial attacks, capable of easily deceiving even state-of-the-art conventional machine learning models. </p>
<p>Moving forward, we’ll need to seriously consider the best ways to protect our systems; an adversary with access to early quantum computers would pose a significant security threat.</p>
<h2>Limitations to overcome</h2>
<p>The current evidence suggests we’re still some years away from quantum machine learning becoming a reality, due to limitations in the current generation of quantum processors.</p>
<p>Today’s quantum computers are relatively small (with fewer than 500 qubits) and their error rates are high. Errors may arise for several reasons, including imperfect fabrication of qubits, errors in the control circuitry, or loss of information (called “<a href="https://en.wikipedia.org/wiki/Quantum_decoherence">quantum decoherence</a>”) through interaction with the environment.</p>
<p>Still, we’ve seen enormous progress in quantum hardware and software over the past few years. According to recent quantum hardware <a href="https://www.ibm.com/quantum/roadmap">roadmaps</a>, it’s anticipated quantum devices made in coming years will have hundreds to thousands of qubits.</p>
<p>These devices should be able to run powerful quantum machine learning models to help protect a large range of industries that rely on machine learning and AI tools.</p>
<p>Worldwide, governments and private sectors alike are increasing their investment in quantum technologies. </p>
<p>This month the Australian government launched the <a href="https://www.industry.gov.au/publications/national-quantum-strategy">National Quantum Strategy</a>, aimed at growing the nation’s quantum industry and commercialising quantum technologies. According to the CSIRO, Australia’s quantum industry <a href="https://www.csiro.au/en/work-with-us/services/consultancy-strategic-advice-services/csiro-futures/future-industries/quantum">could be worth</a> about A$2.2 billion by 2030. </p>
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<a href="https://theconversation.com/australia-has-a-national-quantum-strategy-what-does-that-mean-205232">Australia has a National Quantum Strategy. What does that mean?</a>
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<p class="fine-print"><em><span>Muhammad Usman receives funding under Australian Army Quantum Technology Challenge (QTC). </span></em></p>Quantum machine learning models could help us create AI systems that are almost impenetrable by hackers. But in the hands of hackers, the same technology could wreak havoc.Muhammad Usman, Principal Research Scientist and Team Leader, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2052322023-05-09T01:03:59Z2023-05-09T01:03:59ZAustralia has a National Quantum Strategy. What does that mean?<figure><img src="https://images.theconversation.com/files/524890/original/file-20230508-197326-ujrjbd.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4080%2C2021&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/ERdTJQTtsbE">Dynamic Wang / Unsplash</a></span></figcaption></figure><p>Imagine a world where computers can solve complex problems in seconds, making our current devices seem like mere typewriters. These supercomputers would revolutionise industries, create new medicines, and even help combat climate change. </p>
<p>Imagine as well we could observe the workings of our own bodies in unprecedented detail, and communicate online without fear of hacking. This may be starting to <a href="https://thequantuminsider.com/2021/07/09/quantum-technology-in-science-fiction-popular-culture/">sound like a sci-fi novel</a>, but quantum technologies have the potential to make it all real.</p>
<p>Australia has just unveiled its first <a href="https://www.industry.gov.au/publications/national-quantum-strategy">National Quantum Strategy</a>. The strategy aims to make Australia “a leader of the global quantum industry” by 2030, by encouraging research, applications and commercialisation. </p>
<p>So what does that actually mean?</p>
<h2>What are quantum technologies?</h2>
<p>Quantum technologies build on the science of quantum mechanics, which studies the behaviour of subatomic particles at a microscopic scale. </p>
<p>At this level, particles behave strangely: they can exist in multiple states simultaneously (called superposition), and be “entangled” with each other. When particles are entangled, their properties are linked together regardless of the distance between them. </p>
<p>Quantum technologies make use of these counterintuitive properties to achieve things that might otherwise be impossible. Three main areas of quantum technology are gaining the most attention: quantum sensing, quantum communications, and quantum computing.</p>
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<p>Quantum sensing can detect tiny changes in the environment, measuring things like gravity, magnetic fields and temperature with incredible accuracy. This technology could have a huge impact on industries like healthcare, mining and navigation. </p>
<p>For instance, quantum sensors may be able to help us <a href="https://phys.org/news/2020-11-quantum-nanodiamonds-disease-earlier.html">detect early signs of diseases in our bodies</a> and <a href="https://www.australianmining.com.au/breakthrough-technologies-for-mineral-exploration-fetch-billions/">locate valuable minerals hidden deep underground</a>.</p>
<p>Unlike traditional computers, which store and process information using bits (zeroes and ones), quantum computers use “qubits”, which can exist as zeroes, ones, or combinations of both at once. </p>
<figure class="align-center ">
<img alt="A photo of the brass coils and circuitry of a quantum computer." src="https://images.theconversation.com/files/524999/original/file-20230508-195023-bjjc4v.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524999/original/file-20230508-195023-bjjc4v.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524999/original/file-20230508-195023-bjjc4v.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524999/original/file-20230508-195023-bjjc4v.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524999/original/file-20230508-195023-bjjc4v.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524999/original/file-20230508-195023-bjjc4v.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524999/original/file-20230508-195023-bjjc4v.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Quantum computers may be able to crack problems that are currently impossible to solve.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>Fully functioning quantum computers don’t exist yet – but scientists believe they will be able to perform certain kinds of calculations at lightning speed, solving <a href="https://www.abc.net.au/news/science/2021-08-14/australian-research-puts-larger-quantum-computers-within-reach/100371544">some problems</a> that would take today’s computers millions of years to crack. This would have <a href="https://hbr.org/2021/07/quantum-computing-is-coming-what-can-it-do">huge implications</a> for fields including cryptography, AI, drug discovery, and climate modelling.</p>
<p>Researchers are also working on <a href="https://www.newscientist.com/article/2253448-secure-quantum-communications-network-is-the-largest-of-its-kind/">super-secure quantum communication networks</a> that are almost impossible to hack or eavesdrop on. On networks like these, attempts to intercept messages would be <a href="https://www.bcg.com/publications/2023/are-you-ready-for-quantum-communications">instantly detectable</a> to the sender and the receiver.</p>
<h2>The quantum race</h2>
<p>Australia’s National Quantum Strategy sees us join other countries and regions, racing to unlock the potential of quantum technology and dominate the market. <a href="https://www.forbes.com/sites/forbestechcouncil/2020/10/05/what-the-us-investment-in-quantum-computing-means-for-security/">The United States</a>, <a href="https://www.newscientist.com/article/mg25233652-000-2021-in-review-jian-wei-pan-leads-chinas-quantum-computing-successes/">China</a>, and <a href="https://digital-strategy.ec.europa.eu/en/policies/quantum-technologies-flagship">Europe</a> are investing billions of dollars in quantum research and development. </p>
<p>If Australia wants to keep up, it needs to act now. But why is keeping up so important?</p>
<p>First, we don’t want to be left behind in the rapidly growing quantum technology industry. <a href="https://www.innovationaus.com/australias-quantum-opportunity-upgraded-to-6-billion/">According to CSIRO projections</a>, the quantum industry could be worth A$4.6 billion by the end of the decade. By 2045, it might employ as many people as the oil and gas sector does today, with revenues of $6 billion and 19,400 direct jobs.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/better-ai-unhackable-communication-spotting-submarines-the-quantum-tech-arms-race-is-heating-up-179482">Better AI, unhackable communication, spotting submarines: the quantum tech arms race is heating up</a>
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<p>As other nations push forward, Australia risks missing out on the potential economic benefits. We could also lose talented workers to countries that are investing more in quantum research. Projects like the ambitious attempt to <a href="https://www.smh.com.au/national/australia-sets-ambitious-goal-to-build-first-complete-quantum-computer-20230502-p5d51r.html">build the world’s first complete quantum computer</a> aim to provide local opportunities and funding alongside their top-line goals.</p>
<p>Moreover, Australia has a responsibility to ensure quantum technologies are developed and used ethically, and their <a href="https://www.weforum.org/agenda/2022/09/organizations-protect-quantum-computing-threat-cybersecurity/">risks</a> managed.</p>
<p>For example, quantum computers could enable hackers to <a href="https://www2.deloitte.com/uk/en/insights/topics/cyber-risk/quantum-computing-ethics-risks.html">break existing encryption protocols</a>, leaving internet services vulnerable. Data harvesting by companies is already a concern, and quantum computing could exacerbate this issue. Even <a href="https://www2.deloitte.com/us/en/insights/industry/public-sector/the-impact-of-quantum-technology-on-national-security.html">national security could be jeopardised</a> by quantum decryption.</p>
<h2>Responsible innovation</h2>
<p>To make the most of the power of quantum technology, we need to be proactive, focus on the public good, and think about it from many perspectives to ensure “<a href="https://research.csiro.au/ri/">responsible innovation</a>”.</p>
<p>Collaboration and broad dialogue will be necessary. Conversations between experts in fields like quantum computing, cybersecurity, ethics and social sciences – perhaps via regular conferences or workshops – will help us tackle the technical and ethical risks.</p>
<p>Engaging with society and focusing on the public good will also be essential. The public must be involved in discussions to ensure new quantum technologies benefit everyone, not just businesses. Town hall meetings, public forums or online chats can help scientists, policymakers and citizens share views.</p>
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<strong>
Read more:
<a href="https://theconversation.com/the-second-quantum-revolution-is-almost-here-we-need-to-make-sure-it-benefits-the-many-not-the-few-161878">The 'second quantum revolution' is almost here. We need to make sure it benefits the many, not the few</a>
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<p>And we must make sure that “responsibility” always sits right alongside “innovation” in quantum technologies. Organisations working on quantum tech could have “responsible quantum committees” to address risks and involve stakeholders, ensuring responsible innovation in quantum technology.</p>
<p>Success in quantum technology will be all about striking the right balance: encouraging both innovation and responsibility. By investing in quantum technology and working together to ensure its responsible development, Australia can continue to be a leader in scientific innovation while benefiting from these emerging technologies’ transformative potential. </p>
<p>Australia’s National Quantum Strategy is a step in this direction.</p><img src="https://counter.theconversation.com/content/205232/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jarryd Daymond is an associate researcher on a project funded by the Medical Research Future Fund (MRFF) Targeted Translation Research Accelerator (TTRA). </span></em></p>Countries around the world are racing to develop quantum technologies for computing, sensing and communication. Australia is trying not to get left behind.Jarryd Daymond, Lecturer, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2018492023-03-28T12:15:34Z2023-03-28T12:15:34ZRoom-temperature superconductors could revolutionize electronics – an electrical engineer explains the materials’ potential<figure><img src="https://images.theconversation.com/files/516813/original/file-20230321-14-inrd39.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5472%2C3637&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Room-temperature superconductors could make high-speed maglev trains more practical.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/chinas-600-km-h-high-speed-maglev-transportation-system-news-photo/1329831674">Visual China Group via Getty Images</a></span></figcaption></figure><p>Superconductors make highly efficient electronics, but the ultralow temperatures and ultrahigh pressures required to make them work are costly and difficult to implement. Room-temperature superconductors promise to change that.</p>
<p>The recent announcement by researchers at the University of Rochester of a new material that is <a href="https://doi.org/10.1038/s41586-023-05742-0">a superconductor at room temperature</a>, albeit at high pressure, is an exciting development – if proved. If the material or one like it works reliably and can be economically mass-produced, it could revolutionize electronics.</p>
<p>Room-temperature superconducting materials would lead to many new possibilities for practical applications, including ultraefficient electricity grids, ultrafast and energy-efficient computer chips, and ultrapowerful magnets that can be used to levitate trains and control fusion reactors. </p>
<p>A superconductor is a material that conducts direct current <a href="https://theconversation.com/how-do-superconductors-work-a-physicist-explains-what-it-means-to-have-resistance-free-electricity-202308">without encountering any electrical resistance</a>. Resistance is the property of the material that <a href="https://www.physicsclassroom.com/class/circuits/Lesson-3/Resistance">hinders the flow of electricity</a>. Traditional superconductors must be cooled to extremely low temperatures, close to absolute zero. </p>
<p>In recent decades, researchers have developed so-called <a href="https://doi.org/10.1038/s41586-019-1201-8">high-temperature superconductors</a>, which only have to be chilled to minus-10 degrees Fahrenheit (minus-23 Celsius). Though easier to work with than traditional superconductors, high-temperature superconductors still require special thermal equipment. In addition to cold temperatures, these materials require very high pressure, 1.67 million times more than the atmospheric pressure of 14.6 pounds per square inch (1 bar).</p>
<p>As the name suggests, room-temperature superconductors don’t need special equipment to cool them. They do need to be pressurized, but <a href="https://doi.org/10.1038/s41586-023-05742-0">only to a level that’s about 10,000 times more than atmospheric pressure</a>. This pressure can be achieved by using strong metallic casings. </p>
<h2>Where superconductors are used</h2>
<p>Superconductor electronics refers to electronic devices and circuits that use superconducting materials to achieve extremely high levels of performance and energy efficiency that are orders of magnitude better than can be achieved with state-of-the-art semiconductor devices and circuits. </p>
<p>The lack of electrical resistance in superconducting material means that they can support high electrical currents <a href="https://www.elsevier.com/books/superconductivity/poole/978-0-12-409509-0">without any energy loss due to resistance</a>. This efficiency makes superconductors very attractive for power transmission. </p>
<p>Utility provider Commonwealth Edison <a href="https://www.power-grid.com/td/comed-installs-new-high-temp-conductor-cables-to-improve-resilience-boost-cybersecurity/#gref">installed high-temperature superconducting transmission lines</a> and showcased technologies to bring power to Chicago’s north side for a one-year trial period. Compared to conventional copper wire, the upgraded superconducting wire can carry 200 times the electrical current. But the cost of maintaining the low temperatures and high pressures required for today’s superconductors makes even this efficiency gain impractical in most cases.</p>
<p>Because the resistance of a superconductor is zero, if a current is applied to a superconducting loop, the current <a href="https://www.elsevier.com/books/superconductivity/poole/978-0-12-409509-0">will persist forever unless the loop is broken</a>. This phenomenon can be used in various applications to make large permanent magnets. </p>
<p>Today’s magnetic resonance imaging machines <a href="https://doi.org/10.1088%2F0953-2048%2F30%2F1%2F014007">use superconductor magnets</a> to achieve the magnetic field strength of a few teslas, which is needed for accurate imaging. For comparison, the Earth’s magnetic field has a strength, or flux density, of about 50 microteslas. The magnetic field produced by the superconducting magnet in a 1.5 tesla MRI machine is 30,000 times stronger than that produced by the Earth. </p>
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<figcaption><span class="caption">Superconductors, from theory to applications.</span></figcaption>
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<p>The scanner uses the superconducting magnet <a href="https://doi.org/10.1088%2F0953-2048%2F30%2F1%2F014007">to generate a magnetic field</a> that aligns hydrogen nuclei in a patient’s body. This process combined with radio waves <a href="https://science.howstuffworks.com/mri.htm">produces images of tissue for an MRI exam</a>. The strength of the magnet directly affects the strength of the MRI signal. A 1.5 tesla MRI machine requires longer scan times to create clear images than a 3.0 tesla machine.</p>
<p>Superconducting materials expel magnetic fields from inside themselves, which makes them <a href="https://indico.cern.ch/event/688896/contributions/2975725/attachments/1646140/2630990/20180504_Applications_of_Superconductivity.pdf">powerful electromagnets</a>. These super-magnets have the potential to <a href="http://www.chm.bris.ac.uk/webprojects2000/igrant/uses.html">levitate trains</a>. Superconducting electromagnets generate 8.3 tesla magnetic fields – more than 100,000 times the Earth’s magnetic field. The electromagnets use a current of 11,080 amperes to produce the field, and a superconducting coil allows the high currents to flow without losing any energy. The <a href="https://scmaglev.jr-central-global.com/">Yamanashi superconducting Maglev train</a> in Japan levitates 4 inches (10 centimeters) above its guideway and travels at speeds up to 311 mph (500 kph).</p>
<p>Superconducting circuits are also a promising technology for quantum computing because they can be <a href="https://doi.org/10.1007/s11432-020-2881-9">used as qubits</a>. Qubits are the basic units of quantum processors, analogous to but much more powerful than transistors in classical computers. Companies such as D-Wave Systems, Google and IBM have built quantum computers that use superconducting qubits. Though superconducting circuits make good qubits, they pose some technological challenges to making quantum computers with large numbers of qubits. A key issue is the need to keep the qubits at very low temperatures, which requires the use of large cryogenic devices known as <a href="https://news.fnal.gov/2022/12/its-colossal-creating-the-worlds-largest-dilution-refrigerator/">dilution refrigerators</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="close-up of a computer chip showing colored LEDs scattered among integrated circuits" src="https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=460&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=460&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=460&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=578&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=578&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517795/original/file-20230327-22-3iahqv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=578&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Some quantum computer processors use superconducting circuits.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jurvetson/39188582795">Steve Jurvetson/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>Promise of room-temperature superconductors</h2>
<p>Room-temperature superconductors would remove many of the challenges associated with the high cost of operating superconductor-based circuits and systems and make it easier to use them in the field. </p>
<p>Room-temperature superconductors would enable ultra high-speed digital interconnects for next-generation computers and low-latency broadband wireless communications. They would also enable high-resolution imaging techniques and emerging sensors for biomedical and security applications, materials and structure analyses, and deep-space radio astrophysics. </p>
<p>Room-temperature superconductors would mean MRIs could become much less expensive to operate because they would not require liquid helium coolant, which is expensive and in short supply. Electrical power grids would be at least 20% more power efficient than today’s grids, resulting in billions of dollars saved per year, according to my estimates. Maglev trains could operate over longer distances at lower costs. Computers would run faster with orders of magnitude lower power consumption. And quantum computers could be built with many more qubits, enabling them to solve problems that are far beyond the reach of today’s most powerful supercomputers.</p>
<p>Whether and how soon this promising future of electronics can be realized depends in part on whether the new room-temperature superconductor material can be verified – and whether it can be economically mass-produced.</p><img src="https://counter.theconversation.com/content/201849/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Massoud Pedram receives funding from the U.S. National Science Foundation (NSF), the Defense Advanced Projects Research Agency (DARPA), and the Intelligence Advanced Research Projects Activity (IARPA). </span></em></p>Superconductors make highly efficient electronics, but the ultralow temperatures and ultrahigh pressures make them costly and difficult to use. Room-temperature superconductors promise to change that.Massoud Pedram, Professor of Electrical and Computer Engineering, University of Southern CaliforniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1919302023-01-30T13:12:46Z2023-01-30T13:12:46ZLimits to computing: A computer scientist explains why even in the age of AI, some problems are just too difficult<figure><img src="https://images.theconversation.com/files/506497/original/file-20230125-24-e7inac.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5700%2C3788&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Computers are growing more powerful and more capable, but everything has limits.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/futuristic-semiconductor-and-circuit-board-royalty-free-image/1366897838">Yuichiro Chino/Moment via Getty Images</a></span></figcaption></figure><p>Empowered by artificial intelligence technologies, computers today can <a href="https://www.theatlantic.com/technology/archive/2022/12/openai-chatgpt-chatbot-messages/672411/">engage in convincing conversations</a> with people, <a href="https://www.nbcnews.com/mach/science/ai-can-now-compose-pop-music-even-symphonies-here-s-ncna1010931">compose songs</a>, <a href="https://www.nytimes.com/2022/04/06/technology/openai-images-dall-e.html">paint paintings</a>, play <a href="https://www.wired.com/story/alphabets-latest-ai-show-pony-has-more-than-one-trick/">chess and go</a>, and <a href="https://doi.org/10.1007/s12652-021-03612-z">diagnose diseases</a>, to name just a few examples of their technological prowess. </p>
<p>These successes could be taken to indicate that computation has no limits. To see if that’s the case, it’s important to understand what makes a computer powerful. </p>
<p>There are two aspects to a computer’s power: the number of operations its hardware can execute per second and the efficiency of the algorithms it runs. The hardware speed is limited by the laws of physics. Algorithms – basically <a href="https://theconversation.com/what-is-an-algorithm-how-computers-know-what-to-do-with-data-146665">sets of instructions</a> – are written by humans and translated into a sequence of operations that computer hardware can execute. Even if a computer’s speed could reach the physical limit, computational hurdles remain due to the limits of algorithms.</p>
<p>These hurdles include problems that are impossible for computers to solve and problems that are theoretically solvable but in practice are beyond the capabilities of even the most powerful versions of today’s computers imaginable. Mathematicians and computer scientists attempt to determine whether a problem is solvable by trying them out on an imaginary machine.</p>
<h2>An imaginary computing machine</h2>
<p>The modern notion of an algorithm, known as a Turing machine, was formulated in 1936 by British mathematician <a href="https://www.britannica.com/biography/Alan-Turing/Computer-designer">Alan Turing</a>. It’s an imaginary device that imitates how arithmetic calculations are carried out with a pencil on paper. The Turing machine is the template all computers today are based on.</p>
<p>To accommodate computations that would need more paper if done manually, the supply of imaginary paper in a <a href="https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/turing-machine/one.html">Turing machine</a> is assumed to be unlimited. This is equivalent to an imaginary limitless ribbon, or “tape,” of squares, each of which is either blank or contains one symbol. </p>
<p>The machine is controlled by a finite set of rules and starts on an initial sequence of symbols on the tape. The operations the machine can carry out are moving to a neighboring square, erasing a symbol and writing a symbol on a blank square. The machine computes by carrying out a sequence of these operations. When the machine finishes, or “halts,” the symbols remaining on the tape are the output or result. </p>
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<figcaption><span class="caption">What is a Turing machine?</span></figcaption>
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<p>Computing is often about decisions with yes or no answers. By analogy, a medical test (type of problem) checks if a patient’s specimen (an instance of the problem) has a certain disease indicator (yes or no answer). The instance, represented in a Turing machine in digital form, is the initial sequence of symbols. </p>
<p>A problem is considered “solvable” if a Turing machine can be designed that halts for every instance whether positive or negative and correctly determines which answer the instance yields. </p>
<h2>Not every problem can be solved</h2>
<p>Many problems are solvable using a Turing machine and therefore can be solved on a computer, while many others are not. For example, the domino problem, a variation of the tiling problem formulated by Chinese American mathematician <a href="https://digitalcommons.rockefeller.edu/faculty-members/109/">Hao Wang</a> in 1961, is not solvable. </p>
<p>The task is to use a set of dominoes to cover an entire grid and, following the rules of most dominoes games, matching the number of pips on the ends of abutting dominoes. It turns out that there is no algorithm that can start with a set of dominoes and determine whether or not the set will completely cover the grid.</p>
<h2>Keeping it reasonable</h2>
<p>A number of solvable problems can be solved by algorithms that halt in a reasonable amount of time. These “<a href="https://mathworld.wolfram.com/PolynomialTime.html">polynomial-time algorithms</a>” are efficient algorithms, meaning it’s practical to use computers to solve instances of them.</p>
<p>Thousands of other solvable problems are not known to have polynomial-time algorithms, despite ongoing intensive efforts to find such algorithms. These include the Traveling Salesman Problem. </p>
<p>The Traveling Salesman Problem asks whether a set of points with some points directly connected, called a graph, has a path that starts from any point and goes through every other point exactly once, and comes back to the original point. Imagine that a salesman wants to find a route that passes all households in a neighborhood exactly once and returns to the starting point. </p>
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<figcaption><span class="caption">The Traveling Salesman Problem quickly gets out of hand when you get beyond a few destinations.</span></figcaption>
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<p>These problems, called <a href="https://www.mathsisfun.com/sets/np-complete.html">NP-complete</a>, were independently formulated and shown to exist in the early 1970s by two computer scientists, American Canadian <a href="https://amturing.acm.org/award_winners/cook_n991950.cfm">Stephen Cook</a> and Ukrainian American <a href="https://academickids.com/encyclopedia/index.php/Leonid_Levin">Leonid Levin</a>. Cook, whose work came first, was awarded the 1982 Turing Award, the highest in computer science, for this work.</p>
<h2>The cost of knowing exactly</h2>
<p>The best-known algorithms for NP-complete problems are essentially searching for a solution from all possible answers. The Traveling Salesman Problem on a graph of a few hundred points would take years to run on a supercomputer. Such algorithms are inefficient, meaning there are no mathematical shortcuts.</p>
<p>Practical algorithms that address these problems in the real world can only offer approximations, though <a href="https://theconversation.com/planning-the-best-route-with-multiple-destinations-is-hard-even-for-supercomputers-a-new-approach-breaks-a-barrier-thats-stood-for-nearly-half-a-century-148308">the approximations are improving</a>. Whether there are efficient polynomial-time algorithms that can <a href="https://www.claymath.org/millennium-problems/p-vs-np-problem">solve NP-complete problems</a> is among the <a href="https://www.claymath.org/millennium-problems/millennium-prize-problems">seven millennium open problems</a> posted by the Clay Mathematics Institute at the turn of the 21st century, each carrying a prize of US$1 million.</p>
<h2>Beyond Turing</h2>
<p>Could there be a new form of computation beyond Turing’s framework? In 1982, American physicist <a href="http://www.richardfeynman.com/">Richard Feynman</a>, a Nobel laureate, put forward the idea of computation based on quantum mechanics. </p>
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<figcaption><span class="caption">What is a quantum computer?</span></figcaption>
</figure>
<p>In 1995, Peter Shor, an American applied mathematician, presented a quantum algorithm to <a href="https://www.geeksforgeeks.org/shors-factorization-algorithm/">factor integers in polynomial time</a>. Mathematicians believe that this is unsolvable by polynomial-time algorithms in Turing’s framework. Factoring an integer means finding a smaller integer greater than 1 that can divide the integer. For example, the integer 688,826,081 is divisible by a smaller integer 25,253, because 688,826,081 = 25,253 x 27,277. </p>
<p>A major algorithm called the <a href="https://www.geeksforgeeks.org/rsa-algorithm-cryptography/">RSA algorithm</a>, widely used in securing network communications, is based on the computational difficulty of factoring large integers. Shor’s result suggests that quantum computing, should it become a reality, will <a href="https://theconversation.com/quantum-computers-threaten-our-whole-cybersecurity-infrastructure-heres-how-scientists-can-bulletproof-it-196065">change the landscape of cybersecurity</a>. </p>
<p>Can a full-fledged quantum computer be built to factor integers and solve other problems? Some scientists believe it can be. Several groups of scientists around the world are working to build one, and some have already built small-scale quantum computers. </p>
<p>Nevertheless, like all novel technologies invented before, issues with quantum computation are almost certain to arise that would impose new limits.</p><img src="https://counter.theconversation.com/content/191930/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jie Wang does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In the age of AI, people might wonder if there’s anything computers can’t do. The answer is yes. In fact, there are numerous problems that are beyond the reach of even the most powerful computers.Jie Wang, Professor of Computer Science, UMass LowellLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1960652023-01-12T08:22:48Z2023-01-12T08:22:48ZQuantum computers threaten our whole cybersecurity infrastructure: here’s how scientists can bulletproof it<figure><img src="https://images.theconversation.com/files/502119/original/file-20221220-20-oerjes.jpg?ixlib=rb-1.1.0&rect=105%2C19%2C3089%2C1978&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Against quantum cyber attacks, one can use smarter softwares, or encrypt communications differently in terms of hardware.</span> <span class="attribution"><a class="source" href="https://unsplash.com/fr/photos/wGICoyAhEs4">Salvatore Andrea Santacroce/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><a href="https://www.nature.com/articles/s41586-021-03928-y">Thirteen</a>, <a href="https://www.nature.com/articles/s41586-019-1666-5">53</a> and <a href="https://www.newscientist.com/article/2346074-ibm-unveils-worlds-largest-quantum-computer-at-433-qubits/">433</a>. That’s the size of <em>quantum computers</em> in terms of <a href="https://learn.microsoft.com/en-us/azure/quantum/concepts-the-qubit">quantum bits</a>, or qubits, which has significantly grown in the last years due to important public and private investments and initiatives. Obviously, it is not only a mere question of quantity: the quality of the prepared qubits is as important as their number for a quantum computer to beat our existing classical computers, that is, to attain what’s called the “quantum advantage”. Yet it is conceivable that soon quantum-computing devices delivering such an advantage will be available. How would this affect our daily lives?</p>
<p>Making predictions is never easy, but it is agreed that <em>cryptography</em> will be altered by the advent of quantum computers. It is an almost trivial statement that privacy is a key issue in our information society: every day, immense amounts of confidential data are exchanged through the Internet. The security of these transactions is crucial and mostly depends on a single concept: complexity or, more precisely, computational complexity. Confidential information remains secret because any eavesdropper wanting to read it needs to solve an extremely complex mathematical problem.</p>
<p>In fact, the problems used for cryptography are so complex for our present algorithms and computers that the information exchange remains secure for any practical purposes – solving the problem and then hacking the protocol would take a ridiculous number of years. The most paradigmatic example of this approach is the <a href="https://en.wikipedia.org/wiki/RSA_(cryptosystem)">RSA protocol</a> (for its inventors Ron Rivest, Adi Shamir and Leonard Adleman), which today secures our information transmissions. </p>
<p>The security of the RSA protocol is based on the fact that we don’t yet have any efficient algorithm to <a href="https://medium.com/coinmonks/integer-factorization-defining-the-limits-of-rsa-cracking-71fc0675bc0e">factorise large numbers</a> – given a large number, the goal is to find two numbers whose product is equal to the initial number. For example, if the initial number is 6, the solution is 2 and 3, as 6=2x3. Cryptographic protocols are constructed in such a way that the enemy, to decrypt the message, needs to factorise a <em>very</em> large number (not 6!), which is at present impossible to do.</p>
<p>If computing devices are built for that would allow current cryptography methods to be easily cracked, our current privacy paradigm needs to be rethought. This will be the case for <a href="https://theconversation.com/google-claims-to-have-invented-a-quantum-computer-but-ibm-begs-to-differ-127309">quantum computers</a> (once an operational quantum computer exists, that is): they should be able to break RSA because there is a <a href="https://ieeexplore.ieee.org/abstract/document/365700">quantum algorithm for efficient factorisation</a>. While classical computers may need the age of the universe to such a problem, <em>ideal</em> quantum computers should be able to do it in a <a href="https://arxiv.org/pdf/1905.09749.pdf">few hours</a> or maybe even minutes. </p>
<p>This is why cryptographers are developing solutions to replace RSA and attain <em>quantum-safe security</em>, that is, cryptographic protocols that are secure against an enemy who has access to a quantum computer. To do so, there exist two main approaches: <em>post-quantum cryptography</em> and <em>quantum key distribution</em>.</p>
<h2>How to encrypt information in a world equipped with quantum computers</h2>
<p>Post-quantum cryptography maintains the security paradigm based on complexity. One should look for mathematical problems that remain difficult for quantum computers and use them to construct cryptographic protocols, the idea again being that an enemy can hack them only after a ridiculously large amount of time. Researchers are working hard to develop algorithms for post-quantum cryptography. In fact, the National Institute of Standards and Technology (NIST) initiated a process to <a href="https://csrc.nist.gov/projects/post-quantum-cryptography/selected-algorithms-2022">solicit and evaluate these algorithms</a> and the chosen candidates were announced in July 2022.</p>
<p>Post-quantum cryptography presents a very strong advantage: it is based on software. It is therefore cheap and, more importantly, its integration with existing infrastructures is straightforward, as one only needs to replace the previous protocol, say RSA, by the new one.</p>
<p>[<em>Nearly 80,000 readers look to The Conversation France’s newsletter for expert insights into the world’s most pressing issues</em>. <a href="https://theconversation.com/fr/newsletters/la-newsletter-quotidienne-5?utm_source=inline-70ksignup">Sign up now</a>]</p>
<p>But post-quantum cryptography also has a clear risk: our confidence on the “hardness” of the chosen algorithms against quantum computers is limited. Here it is important to recall that, strictly speaking, none of the cryptographic protocols based on complexity are proven to be secure. In other words, there is no proof that they cannot be solved efficiently on a classical or quantum computer.</p>
<p>This is the case for factoring: one can’t rule out the discovery of an efficient algorithm for factorisation that would enable a classic computer to break down RSA, no quantum computer required. While unlikely, such a possibility cannot be excluded. In the case of the new algorithms, the evidence of their complexity is much more limited, as they have not yet been intensively tested against smart researchers, much less quantum computers. Indeed, a quantum-safe algorithm proposed in the NIST initiative was later <a href="https://thequantuminsider.com/2022/08/05/nist-approved-post-quantum-safe-algorithm-cracked-in-an-hour-on-a-pc/">cracked in an hour on a standard PC</a>.</p>
<h2>Exploit the laws of quantum physics to secure communications</h2>
<p>The second approach for quantum-safe security is <a href="https://www.ssi.gouv.fr/en/publication/should-quantum-key-distribution-be-used-for-secure-communications/"><em>quantum key distribution</em></a>. Here, the security of the protocols is no longer based on complexity considerations, but on the laws of quantum physics. We therefore speak of quantum <em>physical security</em>.</p>
<p>Without entering into the details, a secret key is distributed using qubits and the protocol’s security follows from the <a href="https://en.wikipedia.org/wiki/Uncertainty_principle">Heisenberg uncertainty principle</a>, which implies that any intervention by the eavesdropper is detected because modifies the state of these qubits. The main advantage of quantum key distribution is that it is based on quantum phenomena that have been verified in many experimental labs.</p>
<p>The main problem for its adoption is that it requires new (quantum) hardware. It is therefore expensive and its integration with existing infrastructures is not easy. Yet important initiatives are taking place for the <a href="https://digital-strategy.ec.europa.eu/en/policies/european-quantum-communication-infrastructure-euroqci">deployment of quantum key distribution at a European scale</a>.</p>
<p>Which approach to take? This question is often presented as an either-or choice and even in this article, you may have given this impression too. However, our vision is that the right way to go is to look for the combination of post-quantum and quantum key distribution. The latter has shown us that quantum physics provides us with new tools and recipes to truly safeguard our secrets. If the two approaches are combined, hackers will have a <em>much</em> more difficult time, as they will have to face both complex computational problems and quantum phenomena.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=158&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=158&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=158&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=198&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=198&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=198&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>Created in 2007 to help accelerate and share scientific knowledge on key societal issues, the AXA Research Fund has supported nearly 700 projects around the world conducted by researchers in 38 countries. To learn more, visit the site of the AXA Research Fund or follow on Twitter @AXAResearchFund.</em></p><img src="https://counter.theconversation.com/content/196065/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antonio Acín is ICREA Professor at the ICFO-The Institute of Photonic Sciences. Il received funding from the AXA Research Fund, the European Union and the Spanish and Catalan gouvernments.</span></em></p>To protect against future quantum cyber attacks, two technological paths are being explored. Decryption.Antonio Acín, Professor and group leader, Instituto de Ciencias Fotónicas (ICFO)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1958162022-12-11T19:06:17Z2022-12-11T19:06:17ZDid physicists make a wormhole in the lab? Not quite, but a new experiment hints at the future of quantum simulations<figure><img src="https://images.theconversation.com/files/499159/original/file-20221206-26-iagjnl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Scientists made headlines last week for supposedly generating a wormhole. The research, reported in <a href="https://www.nature.com/articles/s41586-022-05424-3">Nature</a>, involves the use of a quantum computer to simulate a wormhole in a simplified model of physics. </p>
<p>Soon after the news broke, physicists and experts in quantum computing <a href="https://www.math.columbia.edu/%7Ewoit/wordpress/?p=13181">expressed scepticism</a> that a wormhole had in fact been created. </p>
<p>Media coverage was chaotic. Outlets reported that physicists had created a <a href="https://scitechdaily.com/physicists-create-theoretical-wormhole-using-quantum-computer/">theoretical wormhole</a>, a <a href="https://www.quantamagazine.org/physicists-create-a-wormhole-using-a-quantum-computer-20221130/">holographic wormhole</a> or perhaps a <a href="https://www.nytimes.com/2022/11/30/science/physics-wormhole-quantum-computer.html">small, crummy wormhole</a>, and that Google’s quantum computer suggests <a href="https://bigthink.com/hard-science/google-quantum-computer-wormholes-real/">wormholes are real</a>. Other outlets soberly offered the news that no, <a href="https://arstechnica.com/science/2022/12/no-physicists-didnt-make-a-real-wormhole-what-they-did-was-still-pretty-cool/amp/">physicists didn’t make a wormhole at all</a>.</p>
<p>If this has you confused, you’re not alone! What’s going on? </p>
<h2>Wormholes and entanglement</h2>
<p>The Universe is vast. It’s so big that travelling from one side to the other by conventional means is impractical. </p>
<p>Wormholes are a kind of loophole: shortcuts between two regions of the Universe that might allow one to traverse vast distances in a much shorter time. Wormholes are permitted by Einstein’s theory of relativity, but none have ever been found in nature. </p>
<figure class="align-center ">
<img alt="An illustration showing a wormhole joining points in space." src="https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A wormhole is a hypothetical ‘shortcut’ between two regions of space.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/tunnel-wormhole-over-curved-spacetime-travelling-721550755">Shutterstock</a></span>
</figcaption>
</figure>
<p>Recently, physicists have been <a href="https://arxiv.org/abs/1412.8483">toying with the idea</a> that wormholes are related to another phenomenon, known as entanglement. </p>
<p>Entanglement is a peculiar, quantum phenomenon involving particles. When particles are put into an entangled state, measurement of one particle seems to affect the other particle immediately. This is the case even when the two particles are too far apart for causation to be possible. </p>
<p>Some physicists have suggested that a wormhole may just be a way of describing a certain kind of quantum entanglement. If correct, this would forge a link between two prominent theories of physics: quantum mechanics and general relativity. </p>
<p>General relativity explains how gravity works, and describes the Universe on large scales. Quantum mechanics explains the other fundamental forces, and describes the Universe on very small scales.</p>
<figure class="align-center ">
<img alt="Illustration showing two glowing particles connected by faint lines." src="https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=452&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In quantum mechanics, ‘entanglement’ is a kind of link between particles that may be quite distant from one another.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Both are extremely successful theories. However, they are yet to be reconciled into a single, unified theory. </p>
<p>A unified theory would preserve the insights of both quantum mechanics and general relativity, while at the same time providing an account of how gravity works in the quantum domain, something we don’t currently understand.</p>
<p>Because wormholes are distinctive of general relativity, and entanglement is distinctive of quantum mechanics, the potential similarity between them is exciting. It suggests the two theories may, at some level, be describing the very same thing.</p>
<h2>Quantum gravity on a chip?</h2>
<p>How would we look for this potential similarity between wormholes and entanglement? </p>
<p>Well, we know how to entangle particles experimentally. We’ve been doing that for some time. </p>
<p>So we can try to build a particular kind of quantum system: one that can be described using the same physics we use for wormholes. If we can build such a system in the lab and it behaves like a wormhole, it would support the idea that entanglement and wormholes are two sides of the same coin. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">Explainer: quantum computation and communication technology </a>
</strong>
</em>
</p>
<hr>
<p>In quantum computers, the basic components can be put into various quantum states that can be used to run quantum experiments. So, it seems they present an opportunity to test the relationship between wormholes and entanglement. </p>
<p>This is perhaps why it was reported that physicists had used a quantum computer to generate a wormhole. But that does not seem to be what actually happened, though understanding why is not straightforward. </p>
<h2>Not a wormhole</h2>
<p>What physicists did was organise the basic components of a quantum computer into a specific quantum state. They were then able to transfer information from one part of the computer to another through the quantum system. </p>
<p>The quantum system, and the way the information was transferred, can be described using a <a href="https://en.wikipedia.org/wiki/Sachdev%E2%80%93Ye%E2%80%93Kitaev_model">particular model</a> in physics. According to this model, the kind of information transfer that occurred within the computer is descriptively similar to the way that something passes through a wormhole. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-wormholes-an-astrophysicist-explains-these-shortcuts-through-space-time-187828">What are wormholes? An astrophysicist explains these shortcuts through space-time</a>
</strong>
</em>
</p>
<hr>
<p>However, the model being used has at least two limitations. </p>
<p>First, it appears to make unrealistic assumptions about the physics of our world. It assumes, in particular, that spacetime – the fabric of the Universe – has certain properties that it may not have. </p>
<p>Second, the model has been simplified to describe a simple system that can be implemented with a quantum computer. Such a simplified model may be physically inaccurate.</p>
<p>So while we can describe what happened within the computer as though it were a wormhole, using a specific kind of model, it is unclear whether the model represents the world as we know it. </p>
<h2>Experiment and simulation</h2>
<p>Some commentators have offered a different reason to be sceptical that a wormhole was created: it was just a simulation. As <a href="https://futurism.com/headlines-building-wormhole-nonsense">one critic</a> put it, taking the system to be a wormhole “is like claiming that playing the videogame Portal involves creating an actual wormhole because it depicts something akin to the theoretical concept onscreen”. </p>
<p>We must indeed be careful about drawing inferences about reality from simulations. However, the quantum aspect of this simulation makes it more like an experiment than the ordinary simulation you might run on an everyday computer.</p>
<p>So it seems the simulation may legitimately tell us something about the quantum system it is simulating. However, the problem remains that we can only interpret the system as a wormhole in a specific, potentially unrealistic model of physics.</p>
<h2>No wormholes, but still impressive</h2>
<p>So we should perhaps be sceptical that any wormholes were created. Still, there is reason to be impressed. </p>
<p>For one thing, the team used machine-learning techniques to simplify the model they were using to simulate it in a useful way.</p>
<p>The use of machine learning to produce the simplified model is neat, and we should expect to see more uses of machine learning like this in the future.</p>
<p>It’s also important that a quantum computer was used to run the type of quantum experiment at issue. That this can be done at all opens the way toward running further experiments. This may open up an experimental paradigm that can be used to make progress in physics.</p>
<p>There is also the possibility – albeit rather distant – that some aspect of the model that was used to describe the quantum system will be vindicated. This may lead to the discovery of a relationship between quantum entanglement and wormholes in the future. </p>
<p>But this remains very speculative.</p><img src="https://counter.theconversation.com/content/195816/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sam Baron receives funding from the Australian Research Council.</span></em></p>When it comes to physics experiments, quantum simulations aren’t quite the real thing – but in some cases they’re much closer than you’d expect.Sam Baron, Associate Professor, Philosophy of Science, Australian Catholic UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1896742022-10-31T18:35:43Z2022-10-31T18:35:43ZWhat quantum technology means for Canada’s future<figure><img src="https://images.theconversation.com/files/492191/original/file-20221027-23824-csb3yk.png?ixlib=rb-1.1.0&rect=23%2C23%2C3970%2C2622&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A look inside the quantum computing process. Quantum technology is a $142 billion opportunity that could employ 229,000 Canadians by 2040.</span> <span class="attribution"><span class="source">(Photonic)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Canada is a world leader in developing quantum technologies and is well-positioned to secure its place in the emerging quantum industry. </p>
<p><a href="https://qt.eu/discover-quantum/quantum-technologies-in-a-nutshell/">Quantum technologies</a> are new and emerging technologies based on the unique properties of <a href="https://scholar.harvard.edu/files/david-morin/files/waves_quantum.pdf">quantum mechanics</a> — the science that deals with the physical properties of nature on an atomic and subatomic level.</p>
<p>In the future, we’ll see quantum technology transforming computing, communications, cryptography and much more. They will be incredibly powerful, offering capabilities that reach beyond today’s technologies. </p>
<p>The potential impact of these technologies on the Canadian economy will be transformative: the <a href="https://policyoptions.irpp.org/magazines/august-2021/how-to-ensure-canadas-quantum-computing-strategy-is-a-success/">National Research Council of Canada</a> has identified quantum technology as a $142 billion opportunity that could employ 229,000 Canadians by 2040.</p>
<p>Canada could gain far-reaching economic and social benefits from the rapidly developing quantum industry, but it must act now to secure them — before someone else delivers the first large-scale quantum computer, which will likely be sooner than expected.</p>
<h2>Quantum technology is the future</h2>
<p>Quantum computing is a <a href="https://theconversation.com/in-the-future-everyone-might-use-quantum-computers-112063">rapidly-developing type of quantum technology</a> that combines concepts from quantum physics with classical computation. The result is quantum computers, which can accomplish tasks that classical computers can’t.</p>
<p>While quantum computers will be revolutionary, they will also introduce new problems by breaking the public key cryptography that secures today’s internet and corporate networks. <a href="https://doi.org/10.1038/nature23461">Public key cryptography</a> is a method of encrypting data with pairs of keys. Anyone with a public key can encrypt a message, but only those holding the matching private key can decrypt it. </p>
<p>The keys are generated by computers running complex mathematical problems that can’t be broken by today’s most powerful computers, but can be broken by quantum computers. Data intercepted and stored today <a href="https://www.factbasedinsight.com/quantum-crypto-trust-me-ive-come-to-save-the-world">is already vulnerable to this future threat</a>. </p>
<p>This presents an opportunity for Canada to invest in new technologies to secure communications, starting with “post-quantum” encryption algorithms, then layering on
<a href="https://www.techtarget.com/searchsecurity/definition/quantum-key-distribution-QKD">quantum key distribution</a>, a type of provably secure quantum encryption based on quantum mechanics. </p>
<p>To use quantum key distribution over vast distances, we’ll need to develop <a href="https://doi.org/10.1088/1367-2630/abfa63">satellite-based quantum repeaters</a> that function similarly to repeaters in today’s telecommunications fibre networks. They allow quantum signal transmission over long distances. <a href="https://www.asc-csa.gc.ca/eng/satellites/qeyssat.asp">Canadian researchers are well on their way to developing them</a>.</p>
<p>Unless we defend our cybersecurity infrastructure now, the advent of a quantum computer could be the information-security equivalent of the nuclear bomb: almost no information or computing systems would be secure against a future quantum attack. Canada needs to seize the opportunity to lead the world in building, deploying and exporting technology to enable the global quantum internet and protect itself.</p>
<h2>Preparing for the future</h2>
<p>Truly predicting the impact of <a href="https://hbr.org/2021/07/quantum-computing-is-coming-what-can-it-do">large-scale quantum computers</a> is as hard as predicting the changes that followed the commercialization of semiconductor physics. </p>
<p>When the crown jewel of semiconductor microchip technology — transistors — were first commercialized, they were expected to be most helpful in the development of hearing aids. They drove a <a href="https://www.semiconductors.org/semiconductors-101/what-is-a-semiconductor/">computation and communications revolution</a>; <a href="https://www.bbc.com/future/bespoke/made-on-earth/how-the-chip-changed-everything/">today we find the physics of semiconductors inside everything</a> from laptops and phones to cars and medical devices.</p>
<p>Once large-scale quantum physics is commercialized, it will similarly impact almost every field, industry and aspect of our lives. Scientists and engineers will be able to solve all sorts of problems with quantum computers, including simulating and designing drug targets, making better batteries and <a href="https://www.bcg.com/publications/2020/quantum-advantage-fighting-climate-change">creating more efficient ways to produce green hydrogen and synthetic gas</a>.</p>
<h2>Maintaining the lead</h2>
<p>To maintain its leadership, Canada needs to move beyond research and development and accelerate a quantum ecosystem that includes a strong talent pipeline, businesses supported by supply chains and governments and industry involvement. There are a few things Canada can do to drive this leadership: </p>
<p><strong>Continue to fund quantum research:</strong> Canada has <a href="https://www.univcan.ca/media-room/media-releases/how-canadian-universities-are-propelling-us-towards-a-quantum-future/">more than a dozen quantum research institutes and labs</a>, including my <a href="https://www.sfu.ca/physics/siliconquantum/">Silicon Quantum Technologies Lab</a> at Simon Fraser University. The Canadian government has invested more than $1 billion since 2005 in quantum research and will likely announce a national quantum strategy soon. Canada must continue funding quantum research or risk losing its talent base and current competitive advantage.</p>
<p><strong>Build our talent pipeline with more open immigration</strong>: Even though quantum experts are trained in every major university in Canada, the demand for them is <a href="https://thebusinesscouncil.ca/publication/closing-the-quantum-computing-skills-gap-could-make-all-the-difference-in-tackling-climate-change/">three times the number of new graduates</a>. Canada needs the kind of <a href="https://www.ictc-ctic.ca/wp-content/uploads/2012/06/ICTC_IEP_SA_National_EN_03-12.pdf">fast-track immigration programs that fuelled the telecom boom in the 1990s</a>.</p>
<figure class="align-center ">
<img alt="Someone wearing a mask and protective goggles holding a computer microchip in front of their face" src="https://images.theconversation.com/files/492194/original/file-20221027-24414-egb33q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/492194/original/file-20221027-24414-egb33q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492194/original/file-20221027-24414-egb33q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492194/original/file-20221027-24414-egb33q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492194/original/file-20221027-24414-egb33q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492194/original/file-20221027-24414-egb33q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492194/original/file-20221027-24414-egb33q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Transistors are one of the building blocks of modern electronic technology, including computer chips.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p><strong>Be our own best customers</strong>: Canadian companies are leading the way, but they need support. <a href="https://www.quantumindustrycanada.ca/">Quantum Industry Canada</a> boasts of more than 30 member companies. Vancouver is home to <a href="https://www.dwavesys.com/company/about-d-wave/">the pioneering D-Wave</a> and <a href="https://photonic.com/about-photonic/">Photonic Inc.</a>, the company I founded to commercialize silicon quantum technologies. More than <a href="https://www.mckinsey.com/%7E/media/mckinsey/featured%20insights/the%20rise%20of%20quantum%20computing/quantum%20technology%20monitor/2021/mckinsey-quantum-technology-monitor-202109.pdf">$650 million was invested in Canadian startups between 2001 and 2021</a>. On a per capita basis, this is far beyond the $2.1 billion invested in U.S. companies over the same period.</p>
<p>What early quantum companies need most is customers: early, major procurement contracts, or <a href="https://www.darpa.mil/about-us/what-darpa-does">DARPA-like moonshot contracts</a>. Without these contracts, the entire Canadian quantum industry will slip away into other jurisdictions that focus investment and procurement on domestic bidders, like what is happening in <a href="https://doi.org/10.1088/2058-9565/ab042d">the European Union</a> and <a href="https://www.whitehouse.gov/briefing-room/statements-releases/2022/05/04/fact-sheet-president-biden-announces-two-presidential-directives-advancing-quantum-technologies/">the U.S.</a></p>
<h2>Learning from the past</h2>
<p>Canada has an opportunity to break out of its pattern of inventing transformative technology, but not reaping the rewards. This is what happened with the invention of the transistor.</p>
<p>The <a href="https://hackaday.com/2018/12/11/julius-lilienfeld-and-the-first-transistor/">first transistor patent was actually filed in Canada</a> by Canadian-Hungarian physicist Julius Edgar Lilienfeld, 20 years before the Bell Labs demonstration. Canada was also one of the places where <a href="https://www.bce.ca/about-bce/history/timeline">Alexander Graham Bell</a> worked to develop and patent the telephone. </p>
<p>Despite this, the transistor was commercialized in the U.S. and led to the country’s <a href="https://www.ibisworld.com/industry-statistics/market-size/semiconductor-circuit-manufacturing-united-states">US$63 billion semiconductor industry</a>. Bell commercialized the telephone through <a href="https://www.nytimes.com/interactive/2016/02/12/technology/att-history.html">The Bell Telephone Company, which eventually became AT&T</a>.</p>
<p>Canada is poised to make even greater contributions to quantum technology. Much existing technology has been invented here in Canada — including quantum cryptography, <a href="https://sciencebusiness.net/news/canada-lays-groundwork-become-powerhouse-quantum-technology">which was co-invented by University of Montreal professor Gilles Brassard</a>. Instead of repeating its past mistakes, Canada should act now to secure the success of the quantum technology industry.</p><img src="https://counter.theconversation.com/content/189674/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephanie Simmons is the founder and Chief Quantum Officer at Photonic Inc. She is an Associate Professor, Canada Research Chair, and CIFAR Fellow, based out of the Department of Physics at Simon Fraser University (SFU). </span></em></p>Canada is well positioned to gain far-reaching economic and social benefits from the rapidly developing quantum industry, but it must act now to secure its success.Stephanie Simmons, Associate Professor, SFU and Tier 2 Canada Research Chair in Silicon Quantum Technologies, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1919892022-10-25T13:03:37Z2022-10-25T13:03:37ZCould energy efficiency be quantum computers’ greatest strength yet?<figure><img src="https://images.theconversation.com/files/490845/original/file-20221020-26-a4hkfz.jpg?ixlib=rb-1.1.0&rect=0%2C50%2C5568%2C3650&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The energy consumption of large computers is very high – so what about future quantum computers?</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/VT4rx775FT4">maximalfocus/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><a href="https://www.youtube.com/watch?v=bayTbt_8aNc">Quantum computers</a> have attracted considerable interest of late for their potential to crack problems in a few hours where <a href="https://hal.inria.fr/hal-00925622/document">they might take the age of the universe</a> (i.e., tens of billions of years) on the best supercomputers. Their <a href="https://theconversation.com/retour-sur-les-technologies-quantiques-sont-elles-pretes-a-entrer-dans-nos-vies-159740">real-life applications</a> are manifold and range from drugs and materials design to solving complex optimisation problems. They are therefore primarily intended for scientific and industrial research.</p>
<p>Traditionally, <a href="https://theconversation.com/cartes-bleues-et-securite-des-echanges-vers-une-cryptographie-post-quantique-178478">“quantum supremacy”</a> is sought from the point of view of raw computing power: we want to calculate (much) faster.</p>
<p>However, the question of its energy consumption could also now warrant research, with current supercomputers sometimes consuming <a href="https://www.la-croix.com/France/Meta-supercalculateurs-quoi-faire-2022-01-25-1201196837">as much electricity as a small town</a> (which could in fact <a href="http://www.cai2.sk/ojs/index.php/cai/article/view/1960">limit the increase in their computing power</a>). Information technologies, at their end, accounted for <a href="https://www.nature.com/articles/s43246-020-0022-5">11% of global electricity consumption</a> in 2020.</p>
<h2>Why focus on the energy consumption of quantum computers?</h2>
<p>Since a quantum computer can solve problems in a few hours where a supercomputer might take several tens of billions of years, it is natural to expect it will consume much less energy. However, manufacturing such powerful quantum computers will require that we solve many scientific and technological challenges, potentially over one to several decades of research.</p>
<p>A more modest goal would be to create less powerful quantum computers, capable of solving computations in a time relatively comparable to supercomputers, but using much less energy.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/491064/original/file-20221021-20-ppcrlh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491064/original/file-20221021-20-ppcrlh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491064/original/file-20221021-20-ppcrlh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491064/original/file-20221021-20-ppcrlh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491064/original/file-20221021-20-ppcrlh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491064/original/file-20221021-20-ppcrlh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491064/original/file-20221021-20-ppcrlh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Google, Amazon, Microsoft and IBM are some of the tech giants to have taken an interest in quantum computing.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/ibm_research_zurich/40645906341">Graham Carlow</a></span>
</figcaption>
</figure>
<p>This potential energy benefit of quantum computing has already been discussed. Google’s <a href="https://www.nature.com/articles/s41586-019-1666-5">Sycamore quantum processor</a> consumes 26 kilowatts of electrical power, far less than a supercomputer, and runs a test quantum algorithm in seconds. Following the experiment, scientists put forward classical algorithms to simulate the quantum algorithm. The first proposals for classical algorithms required <a href="https://www.ibm.com/blogs/research/2019/10/on-quantum-supremacy/">much more energy</a> – which seemed to demonstrate the energy advantage of quantum computing, but they were soon followed by <a href="https://journals.aps.org/prx/abstract/10.1103/PhysRevX.10.041038">other proposals</a>, which were much more energy efficient.</p>
<p>The question of the energy advantage is therefore still open to question and is an open research topic, especially since the quantum algorithm performed by Sycamore has no identified “useful” application to date.</p>
<h2>Superposition: the fragile phenomenon at the heart of quantum computing</h2>
<p>To know whether quantum computers can be expected to provide an energy advantage, it is necessary to understand the fundamental laws according to which they operate.</p>
<p>Quantum computers manipulate physical systems called <a href="https://azure.microsoft.com/en-us/resources/cloud-computing-dictionary/what-is-a-qubit/">qubits</a> (for <em>quantum bits</em>) to perform a calculation. A qubit can take two values: 0 (the “ground state”, of minimum energy) and 1 (the “excited state”, of maximum energy). It can also occupy a “superposition” of 0 and 1. <a href="https://press.princeton.edu/books/hardcover/9780691183527/philosophy-of-physics">How we interpret superpositions is still the subject of heated philosophical debates</a>, but, to put it simply, it means that the qubit can be “both” in state 0 and state 1 with certain associated <a href="https://www.feynmanlectures.caltech.edu/III_03.html">“probability amplitudes”</a>.</p>
<p>Thanks to these probabilities, we can <a href="https://www.nature.com/articles/nature13460">greatly simplify</a> the principle of the quantum computer by saying that it implements algorithms that perform calculations on several numbers “at once” (in this case 0 and 1 at the same time). This advantage becomes clear when the number of qubits is increased: 300 qubits in superpositions are capable of representing 2 to the power of 300 states at the same time. As an example, <a href="https://www.youtube.com/watch?v=4cwtlmTfNYA">this is approximately the number of atoms in the observable universe</a> – so representing so many states <em>at once</em> on a supercomputer is completely unrealistic.</p>
<figure class="align-center ">
<img alt="A man stands by a quantum computer in California" src="https://images.theconversation.com/files/491014/original/file-20221021-12-dnas7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491014/original/file-20221021-12-dnas7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491014/original/file-20221021-12-dnas7u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491014/original/file-20221021-12-dnas7u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491014/original/file-20221021-12-dnas7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491014/original/file-20221021-12-dnas7u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491014/original/file-20221021-12-dnas7u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Erik Lucero, lead engineer of Google Quantum AI, stands beside a quantum computer in Goleta, California in September.</span>
<span class="attribution"><a class="source" href="https://news.afp.com/#/c/main/search/photos?id=newsml.afp.com.20220922T015329Z.doc-32jv4yv&type=photo">Frederic Brown/AFP</a></span>
</figcaption>
</figure>
<p>However, the foundations of quantum theory tell us that if the values of these probability amplitudes are “measured” by another physical system, then the superposition is destroyed: the qubit relaxes to the value of 1 or 0, thus introducing an error into the calculation.</p>
<p>One concrete example of such a destruction is when the qubit absorbs a photon (a particle of light that is a small packet of energy). If this is the case, it is because it was not in its maximum energy state (since it can absorb energy, that of the photon). The photon, and therefore through it the “environment” of the qubit has therefore indirectly “found” the value of the amplitudes, which destroys the superposition. This is called <a href="https://arxiv.org/abs/quant-ph/0306072">“decoherence”</a>.</p>
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<p>Generally speaking, the challenge is to ensure that the qubits are sufficiently isolated to avoid any information leakage: we can’t allow a photon or another particle to disturb our qubit. This is a challenge because the qubits must also be controllable: they cannot be completely isolated.</p>
<p>This lack of protection is the main source of error in qubit-based calculations. For example, one of the most mature qubit technologies runs into an <a href="https://arxiv.org/abs/1905.13641">error every 1,000 operations</a>. When you consider that <a href="https://arxiv.org/abs/1905.09749">it takes 10¹³ operations</a> for a typical quantum algorithm, you can see that this is far too many.</p>
<h2>Preserving superpositions has an energy cost</h2>
<p>The energy cost of computing a quantum computer will mostly come from this need for “protection of the quantum data”. For example, it is often necessary to set the qubit environment close to absolute zero (-273°C) to ensure that no photons populate this environment, avoiding the problem mentioned above. This is a very energy-intensive process.</p>
<p>Some other techniques, such as <a href="https://www.pourlascience.fr/sd/technologie/les-codes-correcteurs-d-erreurs-quantiques-23810.php">quantum error correction</a>, also preserve quantum information, and can improve the fidelity of operations. However, in addition to the challenges they raise, these techniques also incur a very high energy cost because they involve error detection algorithms, or additional qubits for error detection, etc.</p>
<p>In short, the more accurate we want an operation performed on a qubit to be, the more it will have to be protected, and the more energy we will have to spend for that. There is a very strong link between “error rate” and “energy” in quantum computing. Understanding this link precisely may then allow the design of a very energy efficient computer.</p>
<h2>Is an energy quantum advantage possible?</h2>
<p>Some theoretical studies have been able to calculate the energy cost necessary for the realisation of quantum computers, but in a <a href="https://arxiv.org/abs/2103.16726">non-optimised regime</a>, notably not exploiting the link between error rate and energy, and often with a <a href="https://arxiv.org/abs/2205.12092">simplified model</a> of the computer.</p>
<p>Exploiting this link can lead to powerful optimisations <a href="https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.2.040335">reducing the energy cost of algorithms</a>. In practice, <a href="https://tel.archives-ouvertes.fr/tel-03579666">this requires an interdisciplinary approach</a> including the understanding of the fundamental phenomena inducing decoherence, the modelling of quantum error correction algorithms and codes as well as the whole “engineering” part necessary to control the qubits. One can then calculate the minimal energy cost needed to solve different problems, while aiming at an error probability for the algorithm considered as “acceptable”.</p>
<figure class="align-center ">
<img alt="A disk from a quantum computing system" src="https://images.theconversation.com/files/491081/original/file-20221021-13-3lhsfi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491081/original/file-20221021-13-3lhsfi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491081/original/file-20221021-13-3lhsfi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491081/original/file-20221021-13-3lhsfi.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491081/original/file-20221021-13-3lhsfi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491081/original/file-20221021-13-3lhsfi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491081/original/file-20221021-13-3lhsfi.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A wafer of a D-Wave quantum computing system.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jurvetson/39188583425">Creative Commons Attribution</a></span>
</figcaption>
</figure>
<p>As <a href="https://arxiv.org/abs/2209.05469">we have seen</a>, for qubits of excellent quality (i.e., of a quality that is still out of reach in practice today), there are tasks for which the quantum computer could spend one hundred times less energy than the best current supercomputers for a comparable calculation time (comparable in the sense that both would be able to solve the task in a reasonable time). This energy gain of a factor of 100 is also indicative: one could imagine saving more energy by carrying out additional optimisations.</p>
<p>This is because a quantum computer computes using fundamentally different processes to a classical computer: the former manipulates qubits and the latter bits. Thus, for the same task and even for the same computing time, the number of operations can be drastically different. Moreover, an operation performed in a quantum computer will involve physical processes that are radically different from implemented on a supercomputer. These two remarks taken together imply that, conceptually, even at equal computation time, even if a quantum logic operation consumes more energy than a classical logic operation, the smaller number of quantum logic operations may mean that the quantum computer will ultimately be much more energy-efficient.</p>
<p>Of course, this example comes from theoretical calculations, based on sometimes highly optimistic assumptions. However, it does seem to indicate that one of the primary advantages of quantum computing <a href="https://quantum-energy-initiative.org/">may well be energetic before it is computational</a>.</p><img src="https://counter.theconversation.com/content/191989/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marco Fellous-Asiani ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Recent suggests quantum computers could solve problems with breathtaking speed by comparison to current supermodels.Marco Fellous-Asiani, Post-doctorant en information quantique au Centre of New Technologies, University of WarsawLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1919292022-10-07T13:34:23Z2022-10-07T13:34:23ZNobel-winning quantum weirdness undergirds an emerging high-tech industry, promising better ways of encrypting communications and imaging your body<figure><img src="https://images.theconversation.com/files/488631/original/file-20221006-14-mzyckh.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C3000%2C2384&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Devices like this experimental apparatus can produce pairs of photons that are linked, or 'entangled'.</span> <span class="attribution"><a class="source" href="https://www.ornl.gov/news/researchers-reach-quantum-networking-milestone-real-world-environment">Carlos Jones/ORNL, U.S. Dept. of Energy</a></span></figcaption></figure><p>Unhackable communications devices, high-precision GPS and high-resolution medical imaging all have something in common. These technologies – some under development and some already on the market all rely on the non-intuitive quantum phenomenon of <a href="https://theconversation.com/what-is-quantum-entanglement-a-physicist-explains-the-science-of-einsteins-spooky-action-at-a-distance-191927">entanglement</a>.</p>
<p>Two quantum particles, like pairs of atoms or photons, can become entangled. That means a property of one particle is linked to a property of the other, and a change to one particle instantly affects the other particle, regardless of how far apart they are. This correlation is a key resource in quantum information technologies. </p>
<p>For the most part, quantum entanglement is still a subject of physics research, but it’s also a component of commercially available technologies, and it plays a starring role in the emerging <a href="https://www.google.com/search?hl=en&as_q=list+of+quantum+information+processing+market+research+reports&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=&as_occt=any&safe=images&as_filetype=&tbs=">quantum information processing industry</a>.</p>
<h2>Pioneers</h2>
<p>The <a href="https://theconversation.com/nobel-prize-physicists-share-prize-for-insights-into-the-spooky-world-of-quantum-mechanics-191884">2022 Nobel Prize in Physics</a> recognized the profound legacy of <a href="https://www.nobelprize.org/prizes/physics/2022/aspect/facts/">Alain Aspect</a> of France, <a href="https://www.nobelprize.org/prizes/physics/2022/clauser/facts/">John F. Clauser</a> of the U.S. and Austrian <a href="https://www.nobelprize.org/prizes/physics/2022/zeilinger/facts/">Anton Zeilinger</a>’s experimental work with quantum entanglement, which has personally touched me since the start of my graduate school career as <a href="https://scholar.google.com/citations?hl=en&user=WTPrTLUAAAAJ&view_op=list_works&sortby=pubdate">a physicist</a>. Anton Zeilinger was a mentor of my Ph.D. mentor, <a href="https://physics.illinois.edu/people/directory/profile/kwiat">Paul Kwiat</a>, which heavily influenced my dissertation on experimentally understanding decoherence in photonic entanglement. </p>
<p><a href="https://www.theatlantic.com/science/archive/2018/10/beyond-weird-decoherence-quantum-weirdness-schrodingers-cat/573448/">Decoherence</a> occurs when the environment interacts with a quantum object – in this case a photon – to knock it out of the quantum state of superposition. In <a href="https://scienceexchange.caltech.edu/topics/quantum-science-explained/quantum-superposition">superposition</a>, a quantum object is isolated from the environment and exists in a strange blend of two opposite states at the same time, like a coin toss landing as both heads and tails. Superposition is necessary for two or more quantum objects to become entangled.</p>
<h2>Entanglement goes the distance</h2>
<p>Quantum entanglement is a critical element of quantum information processing, and photonic entanglement of the type pioneered by the Nobel laureates is crucial for transmitting quantum information. Quantum entanglement can be used to build large-scale quantum communications networks.</p>
<p>On a path toward long-distance quantum networks, Jian-Wei Pan, one of Zeilinger’s former students, and colleagues demonstrated entanglement distribution to two locations separated by 764 miles (1,203 km) on Earth <a href="https://doi.org/10.1126/science.aan3211">via satellite transmission</a>. However, direct transmission rates of quantum information are limited due to <a href="https://doi.org/10.1038/ncomms15043">loss</a>, meaning too many photons get absorbed by matter in transit so not enough reach the destination. </p>
<p>Entanglement is critical for solving this roadblock, through the nascent technology of quantum repeaters. An important milestone for early quantum repeaters, called entanglement swapping, <a href="https://link.aps.org/doi/10.1103/PhysRevLett.80.3891">was demonstrated</a> by Zeilinger and colleagues in 1998. Entanglement swapping links one each of two pairs of entangled photons, thereby entangling the two initially independent photons, which can be far apart from each other.</p>
<h2>Quantum protection</h2>
<p>Perhaps the most well known quantum communications application is Quantum Key Distribution (QKD), which allows someone to securely distribute encryption keys. If those keys are stored properly, they will be secure, even from future powerful, code-breaking quantum computers. </p>
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<figcaption><span class="caption">How quantum encryption keeps secrets safe.</span></figcaption>
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<p>While the first proposal for QKD did not explicitly require entanglement, an entanglement-based version was subsequently <a href="https://link.aps.org/doi/10.1103/PhysRevLett.67.661">proposed</a>. Shortly after this proposal came the first demonstration of the technique, through the air over a short distance on a <a href="https://doi.org/10.1007/BF00191318">table-top</a>. The first demonstrations of entangement-based QKD were published by research groups led by <a href="https://doi.org/10.1103/PhysRevLett.84.4729">Zeilinger</a>, <a href="https://doi.org/10.1103/PhysRevLett.84.4737">Kwiat</a> and <a href="https://doi.org/10.1103/PhysRevLett.84.4733">Nicolas Gisin</a> were published in the same issue of Physical Review Letters in May 2000.</p>
<p>These entanglement-based distributed keys can be used to dramatically improve the security of communications. A first important demonstration along these lines was from the Zeilinger group, which conducted a <a href="https://doi.org/10.1364/OPEX.12.003865">bank wire transfer in Vienna, Austria, in 2004</a>. In this case, the two halves of the QKD system were located at the headquarters of a large bank and the Vienna City Hall. The optical fibers that carried the photons were installed in the Vienna sewer system and spanned nine-tenths of a mile (1.45 km).</p>
<h2>Entanglement for sale</h2>
<p>Today, there are a handful of companies that have commercialized quantum key distribution technology, including my group’s collaborator <a href="https://qubitekk.com/">Qubitekk</a>, which focuses on an entanglement-based approach to QKD. With a more recent commercial Qubitekk system, my colleagues and I demonstrated <a href="https://doi.org/10.1038/s41598-022-16090-w">secure smart grid communications</a> in Chattanooga, Tennessee.</p>
<p>Quantum communications, computing and sensing technologies are of <a href="https://idstch.com/technology/photonics/entangled-photon-sources-is-critical-technology-for-secure-communications-systems/">great interest to the military and intelligence communities</a>. Quantum entanglement also promises to boost medical imaging through <a href="https://doi.org/10.1038/srep37714">optical sensing</a> and high-resolution <a href="https://news.engineering.arizona.edu/news/quantum-entanglement-offers-unprecedented-precision-gps-imaging-and-beyond">radio frequency detection</a>, which could also improve GPS positioning. There’s even a company gearing up to <a href="https://www.techrepublic.com/article/quantum-entanglement-as-a-service-the-key-technology-for-unbreakable-networks/">offer entanglement-as-a-service</a> by providing customers with network access to entangled qubits for secure communications.</p>
<p>There are many other quantum applications that have been proposed and have yet to be invented that will be enabled by future entangled quantum networks. Quantum computers will perhaps have the most direct impact on society by enabling direct simulation of problems that do not scale well on conventional digital computers. In general, quantum computers produce complex entangled networks when they are operating. These computers could have huge impacts on society, ranging from reducing energy consumption to developing personally tailored medicine. </p>
<p>Finally, entangled quantum sensor networks promise the capability to measure theorized phenomena, such as dark matter, that cannot be seen with today’s conventional technology. The strangeness of quantum mechanics, elucidated through decades of fundamental experimental and theoretical work, has given rise to a new burgeoning global quantum industry.</p><img src="https://counter.theconversation.com/content/191929/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas Peters receives funding from The United States Department of Energy (DOE) Office of Science Advanced Scientific Computing Research program and DOE's Office of Cybersecurity, Energy Security and Emergency Response. He is affiliated with Oak Ridge National Laboratory. </span></em></p>Quantum entanglement is the stuff of sci-fi, advanced physics research and, increasingly, technology used by governments, banks and the military.Nicholas Peters, Joint Faculty, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1916852022-10-02T12:38:28Z2022-10-02T12:38:28Z100 years of innovation and inventions: South African vice chancellor reflects on what’s next<figure><img src="https://images.theconversation.com/files/487558/original/file-20220930-12-4t7wjk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Vice Chancellor Professor Zeblon Vilakazi and others in the IBM Lab at the opening of Wits university's Tshimologong Digital Innovation Precinct.</span> <span class="attribution"><span class="source">Lauren Mulligan/Wits University</span></span></figcaption></figure><p>We live in a world characterised by <a href="https://www.oxfam.org/en/5-shocking-facts-about-extreme-global-inequality-and-how-even-it">inequality</a>, <a href="https://www.worldbank.org/en/topic/poverty/overview">poverty</a>, economic volatility, globalisation, <a href="https://theconversation.com/africa/topics/climate-change-27">climate change</a> and ambiguity. In my own country, South Africa, residents have to navigate socioeconomic and <a href="https://ewn.co.za/2022/09/30/phalatse-ousted-morero-elected-mayor-as-anc-regains-control-of-joburg">political instability</a>, <a href="https://www.aljazeera.com/news/2022/9/12/south-africa-power-cuts-may-not-end-in-a-year-eskom-says">power</a> and water cuts, <a href="https://www.dw.com/en/pandemic-sees-south-africa-homelessness-numbers-soar/av-62399333">homelessness</a>, unethical governance and mediocre or no service delivery. </p>
<p>It is a far cry from what the country could be if we brought its best talent and resources to bear for the benefit of humanity. </p>
<p>Innovation will be key to any positive changes – and research-intensive universities have a central role to play in that innovation. As the <a href="http://www.wits.ac.za">University of the Witwatersrand</a> (or Wits, as it’s commonly known) turns 100, my colleagues and I have been thinking a great deal about the inventions and breakthroughs that have emerged from the university in the past 100 years – and what <a href="http://www.wits.ac.za/future">is coming next</a>.</p>
<p>Great innovations have emerged from the work done by Wits researchers that have shifted the dial in sectors ranging from health to computing to quantum and nuclear physics. These rich seams of knowledge continue to inform policy and daily decisions and are the foundation of cutting edge research the institution continues to produce.</p>
<h2>100 years of changes</h2>
<p>On 1 September 1939, Adolf Hitler <a href="https://time.com/5659728/poland-1939/">invaded Poland</a>. World War 2 was underway. Barely three months later, the <a href="https://www.theheritageportal.co.za/article/radar-wits-south-africas-development-radar-within-three-months-world-war-ii">first radar set</a> was tested on Wits University’s campus. Britain and its allies were looking for a way to detect enemy aircraft and ships. A group of scientists – among them Sir Basil Schonland, Director of the Bernard Price Institute of Geophysical Research and another Wits engineer, Professor Guerino Bozzoli – came together to harness the power of radio waves.</p>
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<img alt="" src="https://images.theconversation.com/files/487557/original/file-20220930-13-k22ich.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/487557/original/file-20220930-13-k22ich.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=838&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487557/original/file-20220930-13-k22ich.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=838&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487557/original/file-20220930-13-k22ich.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=838&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487557/original/file-20220930-13-k22ich.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1054&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487557/original/file-20220930-13-k22ich.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1054&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487557/original/file-20220930-13-k22ich.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1054&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">An aerial view of the university’s Milner Park campus, 1930.</span>
<span class="attribution"><span class="source">Wits University</span></span>
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<p>Almost a century on, the science of sensors has taken several quantum leaps. <a href="https://www.wits.ac.za/news/latest-news/research-news/2019/2019-11/structured-light-promises-path-to-faster-more-secure-communications.html">Professor Andrew Forbes and his team</a> at Wits are encrypting, transmitting, and decoding data quickly and securely through light beams. He has just secured R54 million for the <a href="https://www.wits.ac.za/witsq/">Wits Quantum Initiative</a> which explores theoretical and experimental quantum science and engineering, secure communications, enhanced quantum-inspired imaging, novel nano and quantum-based sensors and devices. </p>
<p>The university has also come a long way on its computing journey. In 1960 it was the first university in South Africa to <a href="https://www.wits.ac.za/curiosity/stories/when-computers-came-to-wits.html#">own an IBM mainframe computer</a>. Today, in partnership with IBM, we’re the <a href="https://www.wits.ac.za/news/latest-news/research-news/2019/2019-06/wits-enters-the-quantum-computing-universe-with-ibm-q.html">first African university to access a quantum computer</a>. </p>
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<p>As the <a href="https://www.wits.ac.za/future/stories/wits-leads-quantum-computing-national-working-group-.html">Chair of the National Quantum Computing Working Group</a> in South Africa, this is an area where I see immense potential for Africa. Classical computing has served society incredibly well. It gave us the Internet and cashless commerce. It sent humans to the moon, put robots on Mars and smartphones in our pockets. </p>
<p>But many of the world’s biggest mysteries and potentially greatest opportunities remain beyond the grasp of classical computers. To continue the pace of progress, we need to augment the classical approach with a completely new paradigm, one that follows its own set of rules - <a href="https://www.ibm.com/topics/quantum-computing">quantum computing</a>. </p>
<p>This radically new way of performing computer calculations is exponentially faster than any classical computer. It can run new algorithms to solve previously “unsolvable” problems in optimisation, chemistry and machine learning, and its applications are <a href="https://ca.nexteinstein.org/our-work/quantum-leap-africa/">far-reaching</a> – from <a href="https://theconversation.com/quantum-entanglement-what-it-is-and-why-physicists-want-to-harness-it-171608">physics</a> to healthcare.</p>
<p>Innovative healthcare is sorely needed across the African continent. Here, too, Wits has been able to play a vital role in the research, teaching and learning, clinical, social and advocacy spheres. It was the first university to lead <a href="https://www.wits.ac.za/news/latest-news/research-news/2020/2020-06/the-first-covid-19-vaccine-trial-in-south-africa-begins.html">COVID-19</a> vaccination trials in South Africa. </p>
<p>Our researchers also developed <a href="https://www.wits.ac.za/news/latest-news/research-news/2017/2017-09/improving-the-accuracy-of-tb-testing.html">technology to improve the accurate testing for tuberculosis</a>. And the <a href="https://www.pelebox.com/">Pelebox</a>, an invention to cut down the time that patients spend waiting for medication in hospitals. </p>
<p>Elsewhere in the institution, researchers have <a href="https://www.wits.ac.za/news/latest-news/research-news/2017/2017-09/can-you-read-my-mind.html">connected the brain to the internet</a>, <a href="https://www.wits.ac.za/news/latest-news/research-news/2019/2019-11/engineering-pivotal-moves.html">used brainwaves to control a robotic prosthetic hand</a> and developed an affordable <a href="https://wits-enterprise.co.za/innovation-support/innovations/3d-printed-bionic-hand">3D printed bionic hand</a>. </p>
<h2>Difficult questions</h2>
<p>Research intensive universities in South Africa need to ask the difficult questions about their role in a changing society. </p>
<p>How do we serve as a catalyst for social change? How do we best use our intellectual dynamism and work with the public and private sectors to effect positive change? How do we create new, relevant knowledge and translate it into innovation? How do we best develop critical thinkers, innovators, creators and the high-level skills required to advance our economy, and the future world of work? </p>
<p>How do we quantify our social impact and ensure that it is contextually attuned? How do we influence policy change?</p>
<p>These questions are at the heart of the university’s strategy today. And they’re no doubt being considered across the higher education sector as universities work to harness their collective talent and the resources at their disposal to craft a new future and transform society for the benefit of all humanity.</p><img src="https://counter.theconversation.com/content/191685/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zeblon Vilakazi does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Various innovations after the past century have improved the world for many - but there’s still much more for universities to do.Zeblon Vilakazi, Vice-Chancellor and Principal, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1794822022-03-28T19:14:38Z2022-03-28T19:14:38ZBetter AI, unhackable communication, spotting submarines: the quantum tech arms race is heating up<figure><img src="https://images.theconversation.com/files/454591/original/file-20220328-19-w1qfp6.jpg?ixlib=rb-1.1.0&rect=2%2C0%2C1994%2C1203&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Zhu Jin</span></span></figcaption></figure><p>Quantum technology, which makes use of the surprising and often counterintuitive properties of the subatomic universe, is revolutionising the way information is gathered, stored, shared and analysed. </p>
<p>The commercial and scientific potential of the quantum revolution is vast, but it is in national security that quantum technology is making the biggest waves. National governments are by far the heaviest investors in quantum research and development.</p>
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<p>Quantum technology promises breakthroughs in weapons, communications, sensing and computing technology that could change the world’s balance of military power. The potential for strategic advantage has spurred a major increase in funding and research and development in recent years. </p>
<p>The three key areas of quantum technology are computing, communications and sensing. Particularly in the United States and China, all three are now seen as crucial parts of the struggle for economic and military supremacy. </p>
<h2>The race is on</h2>
<p>Developing quantum technology isn’t cheap. Only a small number of states have the organisational capacity and technological know-how to compete. </p>
<p>Russia, India, Japan, the European Union and Australia have established significant quantum research and development programs. But China and the US hold a substantial lead in the new quantum race. </p>
<p>And the race is heating up. In 2015 the US was the world’s largest investor in quantum technology, having spent around US$500 million dollars. By 2021 this investment had grown to almost <a href="https://www2.deloitte.com/content/dam/Deloitte/au/Documents/deloitte-au-quantum-computing-hype-reality-290721.pdf">US$2.1 billion</a>. </p>
<p>However, Chinese investment in quantum technology in the same period expanded from US$300 million to an estimated <a href="https://www2.deloitte.com/content/dam/Deloitte/au/Documents/deloitte-au-quantum-computing-hype-reality-290721.pdf">US$13 billion</a>. </p>
<p>The leaders of the two nations, <a href="https://www.whitehouse.gov/briefing-room/presidential-actions/2022/01/19/memorandum-on-improving-the-cybersecurity-of-national-security-department-of-defense-and-intelligence-community-systems/">Joe Biden</a> and <a href="http://www.xinhuanet.com/english/2020-10/17/c_139447976.htm">Xi Jinping</a>, have both emphasised the importance of quantum technology as a critical national security tool in recent years. </p>
<p>The US federal government has established a “<a href="https://www.quantum.gov/wp-content/uploads/2021/01/NQI-Annual-Report-FY2021.pdf">three pillars model</a>” of quantum research, under which federal investment is split between civilian, defence and intelligence agencies. </p>
<p>In China, information on quantum security programs is more opaque, but the People’s Liberation Army is known to be <a href="https://www.tandfonline.com/doi/abs/10.1080/01402390.2021.1973658">supporting quantum research</a> through its own military science academies as well as extensive funding programs into the broader scientific community.</p>
<h2>Artificial intelligence and machine learning</h2>
<p>Advances in quantum computing could result in <a href="https://www.quantamagazine.org/ai-gets-a-quantum-computing-speedup-20220204/">a leap in artificial intelligence and machine learning</a>. </p>
<p>This could improve the performance of lethal autonomous weapons systems (which can select and engage targets without human oversight). It would also make it easier to analyse the large data sets used in defence intelligence and cyber security. </p>
<p>Improved machine learning may also confer a major advantage in carrying out (and defending against) cyber attacks on both civilian and military infrastructure.</p>
<p>The <a href="https://newsroom.ibm.com/2021-11-16-IBM-Unveils-Breakthrough-127-Qubit-Quantum-Processor">most powerful current quantum computer</a> (as far as we know) is made by the US company IBM, which <a href="https://www.ibm.com/au-en/industries/government/defense-intelligence">works closely</a> with US defence and intelligence.</p>
<h2>Unhackable communication</h2>
<p>Quantum communication systems can be completely secure and unhackable. Quantum communication is also required for networking quantum computers, which is expected to enhance quantum computational power exponentially. </p>
<p>China is the clear global leader here. A quantum communication network using ground and satellite connections already <a href="https://www.nature.com/articles/s41586-020-03093-8">links Beijing, Shanghai, Jinan and Heifei</a>. </p>
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<a href="https://theconversation.com/chinas-quantum-satellite-enables-first-totally-secure-long-range-messages-140803">China's quantum satellite enables first totally secure long-range messages</a>
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<p>China’s prioritisation of secure quantum communications is likely linked to <a href="https://en.wikipedia.org/wiki/Global_surveillance_disclosures_(2013%E2%80%93present)">revelations of US covert global surveillance operations</a>. The US has been by far the most advanced and effective communications, surveillance and intelligence power for the past 70 years – but that could change with a successful Chinese effort.</p>
<h2>More powerful sensors</h2>
<p>Quantum computing and communications hold out the promise of future advantage, but the quantum technology closest to military deployment today is quantum sensing. </p>
<p>New quantum sensing systems offer more sensitive detection and measurement of the physical environment. Existing stealth systems, including the latest generation of warplanes and ultra-quiet nuclear submarines, may no longer be so hard to spot. </p>
<p>Superconducting quantum interference devices (or SQUIDs), which can make extremely sensitive measurements of magnetic fields, are <a href="https://www.newscientist.com/article/2144721-chinas-quantum-submarine-detector-could-seal-south-china-sea/">expected to make it easier to detect submarines underwater</a> in the near future. </p>
<p>At present, undetectable submarines armed with nuclear missiles are regarded as <a href="https://southasianvoices.org/second-strike-sea-based-deterrence-in-south-asia/">an essential deterrent against nuclear war</a> because they could survive an attack on their home country and retaliate against the attacker. Networks of more advanced SQUIDs could make these submarines more detectable (and vulnerable) in the future, upsetting the balance of nuclear deterrence and the logic of mutually assured destruction.</p>
<h2>New technologies, new arrangements</h2>
<p>The US is integrating quantum cooperation agreements into existing alliances such as NATO, as well as into more recent strategic arrangements such as the Australia–UK–US AUKUS security pact and the Quadrilateral Security Dialogue (“the Quad”) between Australia, India, Japan, and the US. </p>
<p>China <a href="https://academic.oup.com/cjip/article-abstract/14/3/447/6352583?redirectedFrom=fulltext">already cooperates with Russia</a> in many areas of technology, and events may well propel closer quantum cooperation. </p>
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<a href="https://theconversation.com/chinas-quest-for-techno-military-supremacy-91840">China's quest for techno-military supremacy</a>
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<p>In the Cold War between the US and the USSR, nuclear weapons were the transformative technology. <a href="https://www.atomicarchive.com/history/cold-war/page-14.html">International standards and agreements</a> were developed to regulate them and ensure some measure of safety and predictability.</p>
<p>In much the same way, new accords and arrangements will be needed as the quantum arms race heats up.</p><img src="https://counter.theconversation.com/content/179482/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stuart Rollo does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>China and the US are racing for quantum technology breakthroughs in weapons, communications, sensing, and computing that could tilt the balance between the world’s military forces.Stuart Rollo, Postdoctoral Research Fellow, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1781642022-03-02T19:06:23Z2022-03-02T19:06:23Z‘An ever-ticking clock’: we made a ‘time crystal’ inside a quantum computer<figure><img src="https://images.theconversation.com/files/449403/original/file-20220302-19-1y1gl9r.jpg?ixlib=rb-1.1.0&rect=4%2C4%2C2991%2C1989&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">IBM</span></span></figcaption></figure><p>You probably know what a crystal is. We’ve all seen one, held one in our hands, and even tasted one on our tongue (for instance sodium chloride crystals, also known as “salt”). </p>
<p>But what on earth is a “time crystal”, if not a sci-fi gadget in the latest Marvel movie? Why do we need a quantum computer to make one? And what is a quantum computer anyway?</p>
<h2>Bits and qubits</h2>
<p>Let’s start there. Computers are all around us. Some are compact, portable and primarily used to stream Netflix, while others fill entire rooms and simulate complex phenomena like the weather or the evolution of our Universe. </p>
<p>Regardless of the details, on a fundamental level computers all have the same purpose: processing information. The information is stored and processed in “bits”.</p>
<p>Any physical system with two identifiably distinct states (call them “0” and “1”) can serve as a bit. Connect lots of bits together in the right way and you can do arithmetic, logic, or what we generally call “computation”. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/449412/original/file-20220302-21-a4jhrz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/449412/original/file-20220302-21-a4jhrz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449412/original/file-20220302-21-a4jhrz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449412/original/file-20220302-21-a4jhrz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449412/original/file-20220302-21-a4jhrz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449412/original/file-20220302-21-a4jhrz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449412/original/file-20220302-21-a4jhrz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A conventional bit can take the values of 0 or 1 - but a quantum bit or qubit can take on a range of complex values in between.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Now, it turns out that the physical world on a very fundamental level is governed by the strange rules of quantum physics. You can also make a quantum version of a bit, called a quantum bit or “qubit”.</p>
<p>Qubits can also be described in terms of two states, “0” and “1”, except they can be both “0” and “1” <em>at the same time</em>. This allows for a much richer form of information processing, and hence more powerful computers.</p>
<h2>What can we do with quantum computers?</h2>
<p>Much of the current research in this area is focused either on building a working quantum computer – a challenging engineering task indeed – or on designing algorithms to do things we can’t manage with our current, classical computers.</p>
<p>Our research, however, is focused on an application first envisioned by the famous US physicist Richard Feynman more than 30 years ago: to use quantum computers to conduct research in fundamental physics. </p>
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Read more:
<a href="https://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">Explainer: quantum computation and communication technology </a>
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<p>As theorists, we typically use a combination of pen-and-paper mathematics and computer simulations to study physical systems. Unfortunately, conventional computers are very ill-equipped for simulating quantum physics. </p>
<p>This is where quantum computers come in. They are already quantum in nature and can, in principle, behave like any quantum system we wish to investigate.</p>
<p>Using IBM’s quantum computer we were able to achieve precisely that, turning it into an experimental simulator to create a novel state of matter, just as envisioned by Feynman. This machine is located in America but can be accessed remotely by researchers around the globe. </p>
<p>Being able to access quantum computers from anywhere in the world represents a major shift in this kind of quantum research.</p>
<h2>Time crystals</h2>
<p>The special type of quantum system we created is called <a href="https://doi.org/10.1126/sciadv.abm7652">a “time crystal”</a>. </p>
<p>I hope you will not be too disappointed when I say you will probably not get to hold one of these in your hands any time soon. But maybe we can at least understand what a time crystal is! </p>
<p>The crucial idea here is that matter exists in different “phases”, like the three familiar phases of water: ice, water and steam. A material can have very different properties depending on which phase we find it in. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/449409/original/file-20220302-27-1gvzn6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/449409/original/file-20220302-27-1gvzn6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=525&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449409/original/file-20220302-27-1gvzn6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=525&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449409/original/file-20220302-27-1gvzn6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=525&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449409/original/file-20220302-27-1gvzn6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=660&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449409/original/file-20220302-27-1gvzn6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=660&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449409/original/file-20220302-27-1gvzn6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=660&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">In a conventional crystal, particles are arranged regularly in space. In a time crystal, they’re arranged regularly in time.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<p>Now a conventional crystal – we might actually call it a “space crystal” - is one such phase of matter. Crystals are characterised by a very regular arrangement of particles in space. </p>
<p>In a time crystal, particles are not only arranged regularly in space, but also in <em>time</em>. The particles move from one position to another and back again, without slowing down or losing energy. </p>
<p>Now this is truly different from what we usually deal with. </p>
<h2>Beyond equilibrium</h2>
<p>The types of phases we normally encounter all have on thing in common: they are in “thermal equilibrium”. If you leave a hot cup of coffee sitting on your desk it will transfer heat to its surroundings until it reaches the same temperature as your room, and then it stops and no changes happen from then on. </p>
<p>If you carefully add a layer of cream to your – now unfortunately cold – coffee and begin stirring, you will see changes happen in time. Coffee and cream will mix in beautiful swirls until the whole thing turns into a uniform light brown liquid, and nothing really changes after that. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/449419/original/file-20220302-27-2wlksd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/449419/original/file-20220302-27-2wlksd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449419/original/file-20220302-27-2wlksd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449419/original/file-20220302-27-2wlksd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449419/original/file-20220302-27-2wlksd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449419/original/file-20220302-27-2wlksd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449419/original/file-20220302-27-2wlksd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Coffee and milk mixed together will create beautiful swirls before eventually reaching a uniform light-brown equilibrium.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>These are examples of “equilibrium”. The common theme is that things in equilibrium do not change over time. </p>
<p>Our time crystal violates this condition. It actually keeps changing indefinitely, for all eternity, without ever reaching equilibrium. </p>
<h2>A loophole in the laws of thermodynamics?</h2>
<p>A time crystal therefore constitutes an out-of-equilibrium phase - in fact, it is one of the first examples of such a strange state of matter. It is essentially like an ever-ticking clock that neither loses energy, nor requires a supply of energy to keep going. </p>
<p>This seems dangerously close to a perpetual motion machine, which would violate the laws of thermodynamics. </p>
<p>But the first law of thermodynamics – which says energy is not created or destroyed - is not in any danger here, as we can’t extract energy from a time crystal while also keeping it running. </p>
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Read more:
<a href="https://theconversation.com/unpacking-a-mystery-of-physics-why-processes-in-nature-operate-only-in-one-direction-177556">Unpacking a mystery of physics: Why processes in nature operate only in one direction</a>
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<p>The second law states that things left to themselves can only become more disordered over time. This concept is probably all too familiar to anyone with kids or housemates.</p>
<p>But there is a loophole. The second law forbids things from becoming more ordered with time, but it doesn’t say they can’t maintain their current level of disorderedness forever.</p>
<p>In everyday life, we don’t see this loophole in action. It is the equivalent of stirring away at your coffee and cream and finding that the swirling tendrils of cream never fully mix with the coffee. </p>
<p>This is what time crystals do. We don’t see it in everyday life because it really is a quantum phenomenon. </p>
<h2>Beyond time crystals</h2>
<p>Quantum computers are still in their infancy. But as they improve they will allow physicists like us to improve our fundamental understanding of nature.</p>
<p>This in turn may translate into technological innovation, just as the physics of the last century enabled the digital revolution that shapes our lives today.</p>
<p>Quantum computers provide a platform for physicists to engineer and investigate novel states of matter that cannot be found in nature. Time crystals just mark the beginning of this exciting endeavour.</p><img src="https://counter.theconversation.com/content/178164/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephan Rachel receives funding from the Australian Research Council (ARC). He is affiliated with the IBM Quantum Hub established at the University of Melbourne.</span></em></p><p class="fine-print"><em><span>Philipp Frey does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Like a coffee you can’t finish stirring, a ‘time crystal’ is a strange quantum state of matter than never settles down to equilibrium.Stephan Rachel, Associate Professor and ARC Future Fellow, The University of MelbournePhilipp Frey, PhD student, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1716082021-12-07T14:58:31Z2021-12-07T14:58:31ZQuantum entanglement: what it is, and why physicists want to harness it<figure><img src="https://images.theconversation.com/files/434373/original/file-20211129-25-djd15g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Two particles are said to be entangled when one cannot be perfectly described without information about the other being included.</span> <span class="attribution"><span class="source">Shutterstock/ezphoto</span></span></figcaption></figure><p>“Quantum entanglement” is one of several plot devices that crops up in modern sci-fi movies. Fans of the <a href="https://www.wired.co.uk/article/marvel-movies-science">Marvel superhero movies</a>, for instance, will be familiar with the idea of different time lines merging and intersecting, or characters’ destinies becoming intertwined through seemingly magical means.</p>
<p>But “quantum entanglement” isn’t just a sci-fi buzzword. It’s a very real, perplexing and useful phenomenon. “Entanglement” is one aspect of the broader collection of ideas in physics known as quantum mechanics, which is a theory that describes the behaviour of nature at the atomic, and even subatomic, level.</p>
<p>Understanding and harnessing entanglement is key to creating many cutting-edge technologies. These include quantum computers, which can solve certain problems far faster than ordinary computers, and quantum communication devices, which would allow us to communicate with one another without the slightest possibility of a eavesdropper listening in.</p>
<p>But what exactly <em>is</em> quantum entanglement? Two particles in quantum mechanics are said to be <em>entangled</em> when one of the particles cannot be perfectly described without including all of the information about the other one: the particles are “connected” in such a way that they are not independent of one another. While this sort of idea may seem to make sense at first glance, it is a difficult concept to grasp – and physicists are still learning more about it.</p>
<h2>Quantum dice</h2>
<p>Suppose that I give you and your friend, Thandi, each a small, opaque black box. Each box contains an ordinary six-sided die. You are both told to lightly shake your boxes to jumble the dice around. Then you part ways. Thandi goes home to one South African city, Cape Town; you return to another, Durban. You don’t communicate with each other during the process. When you get home, you each open your box and look at the upward-facing number on your die. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/434372/original/file-20211129-21-q1lxam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434372/original/file-20211129-21-q1lxam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434372/original/file-20211129-21-q1lxam.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434372/original/file-20211129-21-q1lxam.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434372/original/file-20211129-21-q1lxam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434372/original/file-20211129-21-q1lxam.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434372/original/file-20211129-21-q1lxam.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>Ordinarily, there would be no correlation between the numbers you and Thandi see. She would be equally likely to observe any number between 1 and 6, as would you; importantly, the number she sees on her die would have no bearing whatsoever on the number you see on yours. </p>
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Read more:
<a href="https://theconversation.com/is-reality-a-game-of-quantum-mirrors-a-new-theory-suggests-it-might-be-162936">Is reality a game of quantum mirrors? A new theory suggests it might be</a>
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<p>This is unsurprising – indeed, it’s how the world normally works. However, if we could make this example “quantum”, it could behave quite differently. Suppose that I now tell Thandi and you to first lightly tap your boxes together, before then separately shaking them and heading your separate ways. </p>
<p>In a quantum mechanics analogy, this action of tapping the boxes against one another would enchant the dice and link – or entangle – them in a mysterious fashion: once you each arrive home, open your boxes and look at the numbers, your number and Thandi’s are guaranteed to be perfectly correlated. If you see a ‘4’ in Durban, you know that Thandi in Cape Town is guaranteed to measure a ‘4’ on her die too; if you happen to see a ‘6’, so will she.</p>
<p>In this analogy, the dice represent individual particles (like atoms or particles of light called photons) and the magic act of tapping the boxes together physically is what entangles them, so that measuring one die gives us information about the other.</p>
<h2>Making better entanglement</h2>
<p>As far as we know, there’s no magical box-tapping action to enchant a pair of dice or other objects on our human, macroscopic scale (if there were, we would be able to experience quantum mechanics in our everyday life and it would probably not be such a foreign, perplexing concept). For now, scientists have to be content with using things on the microscopic level, where it is much easier to observe quantum effects, like charged atoms called ions or special superconducting devices called <a href="https://www.youtube.com/watch?v=9MFPvrjHgF0">transmons</a>.</p>
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Read more:
<a href="https://theconversation.com/explainer-what-is-quantum-machine-learning-and-how-can-it-help-us-114627">Explainer: what is quantum machine learning and how can it help us?</a>
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<p>This is the kind of work carried out in the University of the Witwatersrand’s <a href="https://structured-light.org/">Structured Light Laboratory</a>, in South Africa. Instead of ions or transmons, however, researchers in the lab use particles of light, called photons, to better understand quantum mechanics and its implications. We are interested in using the quantum nature of light for a variety of purposes: from designing efficient communication systems which are completely unhackable by a malevolent third party, to creating methods of imaging sensitive biological samples without damaging them. </p>
<p>Studies like this often require us to start with specially created states of entangled photons. But it’s not as simple as putting two dice in separate boxes and tapping them together. The processes used to create entangled photons in a real laboratory are constrained by many experimental variables. These include the shape of laser beams used in experiments and the sizes of small crystals where the entangled photons are created. These can give subpar outputs – or unideal states – that require researchers to selectively throw away some measurements once an experiment is done. This is not an optimal situation: photons are discarded and so energy is wasted.</p>
<p>A group of researchers from the lab, myself among them, recently took a step towards solving this problem. In <a href="https://onlinelibrary.wiley.com/doi/10.1002/qute.202100066">a journal article</a>, we mathematically calculated what the optimal laser shape needs to be in order to, as best as possible, create the entangled state that an experimenter would want to start their experiment with. The method proposes changing the input laser beam shape at the beginning of an experiment to maximise the entangled photon creation process later in the experiment. This will mean more photons available to perform your experiment the way you want to, and fewer stray ones.</p>
<p>Improving the efficiency of the entanglement creation and manipulation process, using techniques such as the one proposed, will be important to optimise the efficiency of a number of other quantum technologies, like quantum cryptography systems and the other technologies already mentioned. This is especially important as the fourth industrial revolution moves ahead globally and technologies with quantum mechanics at their cores undoubtedly <a href="https://www.weforum.org/agenda/2019/10/quantum-computers-next-frontier-classical-google-ibm-nasa-supremacy">become more commonplace</a>.</p><img src="https://counter.theconversation.com/content/171608/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas Bornman receives funding from the CSIR Scarce Skills Programme.</span></em></p>The quantum nature of light can be harnessed for a variety of purposes.Nicholas Bornman, Ph.D. student, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1659562021-08-13T22:17:02Z2021-08-13T22:17:02ZHow a simple crystal could help pave the way to full-scale quantum computing<figure><img src="https://images.theconversation.com/files/415984/original/file-20210813-27-1uv81jl.jpeg?ixlib=rb-1.1.0&rect=0%2C25%2C3360%2C2208&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Serwan Asaad/UNSW</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Vaccine and drug development, artificial intelligence, transport and logistics, climate science — these are all areas that stand to be transformed by the development of a full-scale quantum computer. And there has been <a href="https://www.wsj.com/articles/psiquantum-raises-450-million-to-build-its-quantum-computer-11627387321">explosive growth</a> in quantum computing <a href="https://www.forbes.com/sites/moorinsights/2021/03/23/ionq-takes-quantum-computing-public-with-a-2-billion-deal/?sh=271072285d06">investment</a> over the past decade.</p>
<p>Yet current quantum processors are relatively small in scale, with fewer than 100 <em>qubits</em> — the basic building blocks of a quantum computer. Bits are the smallest unit of information in computing, and the term qubits stems from “quantum bits”.</p>
<p>While early quantum processors have been crucial for demonstrating the potential of quantum computing, realising globally significant applications will likely require processors with <a href="https://www.pnas.org/content/114/29/7555">upwards of a million qubits</a>.</p>
<p>Our new research tackles a core problem at the heart of scaling up quantum computers: how do we go from controlling just a few qubits, to controlling millions? In research <a href="https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abg9158">published today</a> in Science Advances, we reveal a new technology that may offer a solution.</p>
<h2>What exactly is a quantum computer?</h2>
<p>Quantum computers use qubits to hold and process quantum information. Unlike the bits of information in classical computers, qubits make use of the quantum properties of nature, known as “superposition” and “entanglement”, to perform some calculations much faster than their classical counterparts.</p>
<p>Unlike a classical bit, which is represented by either 0 or 1, a qubit can exist in <em>two</em> states (that is, 0 and 1) at the same time. This is what we refer to as a superposition state.</p>
<p>Demonstrations by <a href="https://www.nature.com/articles/s41586-019-1666-5">Google</a> and <a href="https://science.sciencemag.org/content/370/6523/1460">others</a> have shown even current, early-stage quantum computers can outperform the most powerful supercomputers on the planet for a highly specialised (albeit not particularly useful) task — reaching a milestone we call quantum supremacy.</p>
<p>Google’s quantum computer, built from superconducting electrical circuits, had just 53 qubits and was cooled to a temperature close to -273°C in a high-tech refrigerator. This extreme temperature is needed to remove heat, which can introduce errors to the fragile qubits. While such demonstrations are important, the challenge now is to build quantum processors with many more qubits.</p>
<p>Major efforts are underway at UNSW Sydney to make quantum computers from the same material used in everyday computer chips: silicon. A conventional silicon chip is thumbnail-sized and packs in several billion bits, so the prospect of using this technology to build a quantum computer is compelling.</p>
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Read more:
<a href="https://theconversation.com/quantum-computers-could-arrive-sooner-if-we-build-them-with-traditional-silicon-technology-123115">Quantum computers could arrive sooner if we build them with traditional silicon technology</a>
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<h2>The control problem</h2>
<p>In silicon quantum processors, information is stored in individual electrons, which are trapped beneath small electrodes at the chip’s surface. Specifically, the qubit is coded into the electron’s <a href="https://en.wikipedia.org/wiki/Spin_(physics)">spin</a>. It can be pictured as a small compass inside the electron. The needle of the compass can point north or south, which represents the 0 and 1 states. </p>
<p>To set a qubit in a superposition state (both 0 <em>and</em> 1), an operation that occurs in all quantum computations, a control signal must be directed to the desired qubit. For qubits in silicon, this control signal is in the form of a microwave field, much like the ones used to carry phone calls over a 5G network. The microwaves interact with the electron and cause its spin (compass needle) to rotate.</p>
<p>Currently, each qubit requires its own microwave control field. It is delivered to the quantum chip through a cable running from room temperature down to the bottom of the refrigerator at close to -273°C. Each cable brings heat with it, which must be removed before it reaches the quantum processor.</p>
<p>At around 50 qubits, which is state-of-the-art today, this is difficult but manageable. Current refrigerator technology can cope with the cable heat load. However, it represents a huge hurdle if we’re to use systems with a million qubits or more.</p>
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<h2>The solution is ‘global’ control</h2>
<p>An elegant solution to the challenge of how to deliver control signals to millions of spin qubits was <a href="https://www.nature.com/articles/30156">proposed in the late 1990s</a>. The idea of “global control” was simple: broadcast a single microwave control field across the entire quantum processor. </p>
<p>Voltage pulses can be applied locally to qubit electrodes to make the individual qubits interact with the global field (and produce superposition states).</p>
<p>It’s much easier to generate such voltage pulses on-chip than it is to generate multiple microwave fields. The solution requires only a single control cable and removes obtrusive on-chip microwave control circuitry. </p>
<p>For more than two decades global control in quantum computers remained an idea. Researchers could not devise a suitable technology that could be integrated with a quantum chip and generate microwave fields at suitably low powers.</p>
<p>In our work we show that a component known as a dielectric resonator could finally allow this. The dielectric resonator is a small, transparent crystal which traps microwaves for a short period of time. </p>
<p>The trapping of microwaves, a phenomenon known as resonance, allows them to interact with the spin qubits longer and greatly reduces the power of microwaves needed to generate the control field. This was vital to operating the technology inside the refrigerator.</p>
<p>In our experiment, we used the dielectric resonator to generate a control field over an area that could contain up to four million qubits. The quantum chip used in this demonstration was a device with two qubits. We were able to show the microwaves produced by the crystal could flip the spin state of each one.</p>
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<span class="caption">Illustration of a crystal dielectric resonator producing a global control field in a spin quantum processor.</span>
<span class="attribution"><span class="source">Tony Melov</span></span>
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<h2>The path to a full-scale quantum computer</h2>
<p>There is still work to be done before this technology is up to the task of controlling a million qubits. For our study, we managed to flip the state of the qubits, but not yet produce arbitrary superposition states. </p>
<p>Experiments are ongoing to demonstrate this critical capability. We’ll also need to further study the impact of the dielectric resonator on other aspects of the quantum processor.</p>
<p>That said, we believe these engineering challenges will ultimately be surmountable — clearing one of the greatest hurdles to realising a large-scale spin-based quantum computer.</p>
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<a href="https://theconversation.com/error-correcting-the-things-that-go-wrong-at-the-quantum-computing-scale-84846">Error correcting the things that go wrong at the quantum computing scale</a>
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<img src="https://counter.theconversation.com/content/165956/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jarryd Pla receives funding from the Australian Research Council. He is also an inventor on patents related to quantum computing.</span></em></p><p class="fine-print"><em><span>Andrew Dzurak receives research funding from the Australian Research Council and the US Army Research Office. He is a member of the Executive Board of the Sydney Quantum Academy and a member of the Executive of the ARC Centre of Excellence for Quantum Computation and Communication Technology. He is also an inventor on a number of patents related to quantum computing.</span></em></p>So far researchers have only been able to control a handful of qubits — the basic units of information in a quantum computer. A new approach could help them control millions at a time.Jarryd Pla, Senior Lecturer in Quantum Engineering, UNSW SydneyAndrew Dzurak, Scientia Professor in Quantum Engineering, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1618782021-06-08T03:35:44Z2021-06-08T03:35:44ZThe ‘second quantum revolution’ is almost here. We need to make sure it benefits the many, not the few<figure><img src="https://images.theconversation.com/files/404158/original/file-20210603-21-p9e4s3.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C5158%2C3521&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Steve Jurvetson/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Over the past six years, quantum science has <a href="https://www.economist.com/news/essays/21717782-quantum-technology-beginning-come-its-own">noticeably shifted</a>, from the domain of physicists concerned with learning about the universe on extremely small scales, to a source of new technologies we all might use for practical purposes. These technologies make use of quantum properties of single atoms or particles of light. They include sensors, communication networks, and computers. </p>
<p>Quantum technologies are expected to impact <a href="https://quantumcity.org.uk/">many aspects of our society</a>, including health care, financial services, defence, weather modelling, and cyber security. Clearly, they promise exciting benefits. Yet the history of technology development shows we cannot simply assume new tools and systems will automatically be in the public interest. </p>
<p>We must look ahead to what a quantum society might entail and how the quantum design choices made today might impact how we live in the near future. The <a href="https://www.technologyreview.com/2021/04/23/1023549/kate-crawford-atlas-of-ai-review/">deployment of artificial intelligence and machine learning</a> over the past few years provides a <a href="https://www.netflix.com/au/title/81328723">compelling example</a> of why this is necessary. </p>
<p>Let’s consider an example. Quantum computers are perhaps the best-known quantum technology, with companies like Google and IBM competing to achieve quantum computation. The advantage of quantum computers lies in their ability to tackle incredibly complex tasks that would take a normal computer millions of years. One such task is simulating molecules’ behaviour to improve predictions about the properties of prospective new drugs and accelerate their development. </p>
<p>One conundrum posed by quantum computing is the sheer expense of investing in the physical infrastructure of the technology. This means ownership will likely be concentrated among the wealthiest countries and corporations. In turn, this could <a href="https://link.springer.com/article/10.1007/s10676-017-9439-z#Sec6">worsen uneven power distribution</a> enabled by technology. </p>
<p>Other considerations for this particular type of quantum technology include <a href="https://theconversation.com/is-quantum-computing-a-cybersecurity-threat-107411">concerns about reduced online privacy</a>.</p>
<p>How do we stop ourselves <a href="https://link.springer.com/article/10.1007/s11024-012-9204-8">blundering into a quantum age</a> without due forethought? How do we tackle the societal problems posed by quantum technologies, while nations and companies race to develop them? </p>
<h2>Charting a path</h2>
<p>Last year, CSIRO released a <a href="https://www.csiro.au/en/work-with-us/services/consultancy-strategic-advice-services/csiro-futures/futures-reports/quantum">roadmap</a> that included a call for quantum stakeholders to explore and address social risks. An example of how we might proceed with this has <a href="https://www.weforum.org/projects/quantum-computing-ethics">begun at the World Economic Forum (WEF)</a>. The WEF is convening experts from industry, policy-making, and research to promote safe and secure quantum technologies by establishing an agreed set of ethical principles for quantum computing. </p>
<p>Australia should draw on such initiatives to ensure the quantum technologies we develop <a href="https://theconversation.com/scientists-want-to-build-trust-in-science-and-technology-the-alternative-is-too-risky-to-contemplate-116269">work for the public good</a>. We need to diversify the people involved in quantum technologies — in terms of the types of expertise employed and the social contexts we work from — so we don’t reproduce and amplify existing problems or create new ones. </p>
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Read more:
<a href="https://theconversation.com/scientists-want-to-build-trust-in-science-and-technology-the-alternative-is-too-risky-to-contemplate-116269">Scientists want to build trust in science and technology. The alternative is too risky to contemplate</a>
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<p>While we work to shape the impacts of individual quantum technologies, we should also <a href="https://iopscience.iop.org/article/10.1088/2058-9565/abc5ab">review the language</a> used to describe this “second quantum revolution”. </p>
<p>The rationale most commonly used to advocate for the field narrowly imagines public benefit of quantum technologies in terms of economic gain and competition between nations and corporations. But framing this as a “<a href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3446708">race</a>” to develop quantum technologies means prioritising urgency, commercial interests and national security at the expense of more civic-minded concerns. </p>
<p>It’s still early enough to do something about the challenges posed by quantum technologies. It’s also not all doom and gloom, with a variety of <a href="https://quantumdelta.nl/welcome-to-living-lab-quantum-and-society/">initiatives</a> and <a href="https://cifar.ca/wp-content/uploads/2021/04/quantum-report-EN-10-accessible.pdf">national research and development policies</a> setting out to tackle these problems before they are set in stone.</p>
<p>We need discussions involving a cross-section of society on the potential impacts of quantum technologies on society. This process should clarify societal expectations for the emerging quantum technology sector and inform any <a href="https://www.aspi.org.au/report/australian-strategy-quantum-revolution">national quantum initiative in Australia</a>. </p>
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Read more:
<a href="https://theconversation.com/why-are-scientists-so-excited-about-a-recently-claimed-quantum-computing-milestone-124082">Why are scientists so excited about a recently claimed quantum computing milestone?</a>
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<p class="fine-print"><em><span>Tara Roberson is a research fellow within the Australian Research Council Centre of Excellence for Engineered Quantum Systems. She is supported by the CSIRO's Responsible Innovation initiative. </span></em></p>The focus of quantum science has shifted from theoretical physics to the advent of new technologies such as quantum computers. The benefits could be immense, but there are also potential pitfalls.Tara Roberson, Postdoctoral Research Fellow, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1559272021-02-25T12:04:31Z2021-02-25T12:04:31ZLeaving Hong Kong after China’s clampdown: where are people thinking of going and why? – The Conversation Weekly podcast<p>In this week’s episode of <a href="https://theconversation.com/uk/topics/the-conversation-weekly-98901">The Conversation Weekly</a> podcast, three experts explain why more people are thinking of leaving Hong Kong after China’s clampdown on dissent – and the choices they face about where to go. And we hear about new research that found a new way to speed up the search for one of the universe’s most elusive enigmas: dark matter. </p>
<iframe src="https://embed.acast.com/60087127b9687759d637bade/6036629da9f63074a33de340?cover=true&ga=false" frameborder="0" allow="autoplay" width="100%" height="110"></iframe>
<p><iframe id="tc-infographic-561" class="tc-infographic" height="100" src="https://cdn.theconversation.com/infographics/561/4fbbd099d631750693d02bac632430b71b37cd5f/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Since China imposed a new National Security Law on Hong Kong in mid-2020, the situation for political protesters has become much more dangerous. Many of those involved in recent pro-democracy protests are being <a href="https://apnews.com/article/legislature-primary-elections-democracy-hong-kong-elections-25a66f7dd38e6606c9f8cce84106d916">rounded up and arrested</a>. </p>
<p>Many Hong Kongers are now thinking about leaving – and in this episode we hear from experts researching what is influencing these decisions. Sui-Ting Kong, assistant professor in sociology at Durham University, who has been interviewing Hong Kongers about the way political participation affects their everyday lives, sets out three different ways people have described the decision to migrate. For one group – those who say they are “fleeing from disaster” – she says: “They find it really difficult to reconcile the idea of moving away from Hong Kong while they have invested so much energy, sacrificed so much in the movement, to make Hong Kong a better place for themselves.”</p>
<p>At the end of January, the UK government opened up a new visa route for those who qualify for British National Overseas (BNO) status. We hear from Peter Walsh, a researcher at the Migration Observatory at the University of Oxford, who explains the history of BNO status, how the new visa route will work and why the UK government has no clear idea about how many people will apply. </p>
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Read more:
<a href="https://theconversation.com/hong-kong-china-crackdown-is-likely-to-boost-migration-to-uk-152766">Hong Kong: China crackdown is likely to boost migration to UK</a>
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<p>But it’s Taiwan, not the UK, which is the most <a href="https://foreignpolicy.com/2020/07/08/hong-kong-exile-taiwan-first-choice/">attractive migration destination</a> for Hong Kongers. Tsungyi Michelle Huang, professor of geography at National Taiwan University, tells us about her research on how Hong Kongers’ attitudes towards Taiwan have shifted in recent years. But she says that there is some suspicion emerging in Taiwan about a recent <a href="https://www.bloomberg.com/news/articles/2021-02-03/hong-kongers-move-to-taiwan-in-record-numbers-amid-turmoil">increase in migration</a> from Hong Kong. “Taiwanese are worried whether many of the Hong Kongers who have immigrated to Taiwan are actually mainlanders,” she tells us, “because of this distrust of the Chinese.”</p>
<p>In our second story, we’re joined by Benjamin Brubaker, a physicist at the University of Colorado, Boulder, who is on the hunt for dark matter. Dark matter is invisible, but it accounts for 85% of the matter in the universe. You can’t detect it and it’s matter, so, “dark matter”. Based on a bunch of clues – from how galaxies move to how light bends in space – we know dark matter has to exist, but no one has ever figured out what it actually is. </p>
<p>Physicists around the world are running special detectors to try and find evidence of a dark matter particle. But this is an incredibly slow process. Brubaker has worked on the Haystac detector that looks for one of the potential dark matter particles called an axion. He <a href="https://theconversation.com/the-search-for-dark-matter-gets-a-speed-boost-from-quantum-technology-153604">just published a paper</a> explaining how he and his colleagues used technology from the quantum computing world to speed up the search for dark matter. </p>
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Read more:
<a href="https://theconversation.com/the-search-for-dark-matter-gets-a-speed-boost-from-quantum-technology-153604">The search for dark matter gets a speed boost from quantum technology</a>
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<p>And to end this week’s episode, Luthfi Dzulfikar, associate editor at The Conversation in Jakarta, recommends a couple of stories by academics in Indonesia. </p>
<p>The Conversation Weekly is produced by Mend Mariwany and Gemma Ware, with sound design by Eloise Stevens. Our theme music is by Neeta Sarl.</p>
<p>News clips in this episode from <a href="https://www.youtube.com/watch?v=dvDMjlguBDk">CBC News</a>, <a href="https://www.youtube.com/watch?v=FBXgKblIFRg">France 24</a>, <a href="https://www.youtube.com/watch?v=pZtfpxXMTwk">BBC</a> <a href="https://www.youtube.com/watch?v=pZtfpxXMTwk">News</a>, <a href="https://www.youtube.com/watch?v=gHfWuUhrKQg&has_verified=1">NYT</a>, <a href="https://www.youtube.com/watch?v=GBeD3ntGOlw">Global News</a>, <a href="https://www.youtube.com/watch?v=pWm_3_saGvI">ViuTV News</a>, <a href="https://www.youtube.com/watch?v=zQG3cheC1gE">AJE</a>, <a href="https://www.youtube.com/watch?v=79mcI7TGjgY">CNA</a>, <a href="https://www.youtube.com/watch?v=rMaAfiye-X0">NBC News</a> and <a href="https://www.youtube.com/watch?v=VF0I_3howHk">CNN</a>. </p>
<p>A transcript of this episode is <a href="https://theconversation.com/hong-kong-political-turmoil-provokes-difficult-decisions-about-whether-to-leave-155994">available here</a>. </p>
<p><em>You can listen to The Conversation Weekly via any of the apps listed above, our <a href="https://feeds.acast.com/public/shows/60087127b9687759d637bade">RSS feed</a>, or find out how else to <a href="https://theconversation.com/how-to-listen-to-the-conversations-podcasts-154131">listen here</a>.</em></p><img src="https://counter.theconversation.com/content/155927/count.gif" alt="The Conversation" width="1" height="1" />
Plus new research finds a way to speed up the search for dark matter. Listen to episode 4 of The Conversation Weekly.Gemma Ware, Head of AudioDaniel Merino, Associate Breaking News Editor and Co-Host of The Conversation Weekly PodcastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1536042021-02-10T16:10:01Z2021-02-10T16:10:01ZThe search for dark matter gets a speed boost from quantum technology<figure><img src="https://images.theconversation.com/files/383391/original/file-20210209-17-u0002r.jpg?ixlib=rb-1.1.0&rect=138%2C421%2C3610%2C2895&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dark matter can be inferred from an assortment of physical clues in the universe.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Dark_matter#/media/File:Gravitationell-lins-4.jpg">NASA</a></span></figcaption></figure><p>Nearly a century after dark matter was first proposed to explain the motion of galaxy clusters, physicists still have no idea what it’s made of.</p>
<p>Researchers around the world have built dozens of detectors in hopes of discovering dark matter. As a graduate student, <a href="https://scholar.google.com/citations?user=lA_CluMAAAAJ&hl=en&oi=ao">I helped design and operate</a> one of these detectors, aptly named <a href="https://haystac.yale.edu/">HAYSTAC</a>. But despite decades of experimental effort, scientists have yet to identify the dark matter particle.</p>
<p>Now, the search for dark matter has received an unlikely assist from technology used in quantum computing research. In a <a href="https://www.nature.com/articles/s41586-021-03226-7">new paper</a> published in the journal Nature, my colleagues on the HAYSTAC team and I describe how we used a bit of quantum trickery to double the rate at which our detector can search for dark matter. Our result adds a much-needed speed boost to the hunt for this mysterious particle.</p>
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<span class="caption">The HAYSTAC detector is searching for the axion, one of the hypothetical particles that could make up dark matter.</span>
<span class="attribution"><span class="source">Kelly Backes</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Scanning for a dark matter signal</h2>
<p>There is <a href="https://theconversation.com/why-do-astronomers-believe-in-dark-matter-122864">compelling evidence</a> from astrophysics and cosmology that an unknown substance called dark matter constitutes more than 80% of the matter in the universe. Theoretical physicists have proposed <a href="https://www.symmetrymagazine.org/article/what-could-dark-matter-be">dozens of new fundamental particles</a> that could explain dark matter. But to determine which – if any – of these theories is correct, researchers need to build different detectors to test each one.</p>
<p>One prominent theory proposes that dark matter is made of as-yet <a href="https://arxiv.org/abs/1712.03018">hypothetical particles</a> called <a href="https://www.symmetrymagazine.org/article/the-other-dark-matter-candidate">axions</a> that collectively behave like an invisible wave oscillating at a very specific frequency through the cosmos. <a href="https://doi.org/10.1146/annurev-nucl-102014-022120">Axion detectors</a> – including HAYSTAC – work something like radio receivers, but instead of converting radio waves to sound waves, they aim to convert axion waves into electromagnetic waves. Specifically, axion detectors measure two quantities called <a href="https://doi.org/10.1103/RevModPhys.77.513">electromagnetic field quadratures</a>. These quadratures are two distinct kinds of oscillation in the electromagnetic wave that would be produced if axions exist.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An old radio with a manual tuning dial." src="https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=485&fit=crop&dpr=1 600w, https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=485&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=485&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=609&fit=crop&dpr=1 754w, https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=609&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/383418/original/file-20210209-17-kk18e6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=609&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The way axion detectors search for signals is similar to the way you might search for a radio station.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Vintage_Sony_11_Transistor_Radio,_Model_TFM-110W,_AM-FM_Bands,_Made_In_Japan,_Circa_1965_(20167123919).jpg#/media/File:Vintage_Sony_11_Transistor_Radio,_Model_TFM-110W,_AM-FM_Bands,_Made_In_Japan,_Circa_1965_(20167123919).jpg">Joe Haupt</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The main challenge in the search for axions is that nobody knows the frequency of the hypothetical axion wave. Imagine you’re in an unfamiliar city searching for a particular radio station by working your way through the FM band one frequency at a time. Axion hunters do much the same thing: They tune their detectors over a wide range of frequencies in discrete steps. Each step can cover only a very small range of possible axion frequencies. This small range is the bandwidth of the detector. </p>
<p>Tuning a radio typically involves pausing for a few seconds at each step to see if you’ve found the station you’re looking for. That’s harder if the signal is weak and there’s a lot of static. An axion signal – in even the most sensitive detectors – would be extraordinarily faint compared with static from random electromagnetic fluctuations, which physicists call <a href="https://en.wikipedia.org/wiki/Noise_(signal_processing)">noise</a>. The more noise there is, the longer the detector must sit at each tuning step to listen for an axion signal.</p>
<p>Unfortunately, researchers can’t count on picking up the axion broadcast after a few dozen turns of the radio dial. An FM radio tunes from only 88 to 108 megahertz (one megahertz is one million hertz). The axion frequency, by contrast, may be anywhere between 300 hertz and 300 billion hertz. At the rate <a href="https://doi.org/10.1103/PhysRevLett.118.061302">today’s</a> <a href="https://doi.org/10.1103/PhysRevLett.120.151301">detectors</a> are going, finding the axion or proving that it doesn’t exist could take <a href="https://jila.colorado.edu/bibcite/reference/12122">more than 10,000 years</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A superconducting circuit, a small gold-colored square mounted onto a golden metal board." src="https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/383392/original/file-20210209-15-32k1dp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Special superconducting circuits used for quantum computing can help detectors sift through noise that might be hiding an axion signal.</span>
<span class="attribution"><span class="source">Kelly Backes</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Squeezing the quantum noise</h2>
<p>On the HAYSTAC team, we don’t have that kind of patience. So in 2012 we set out to speed up the axion search by doing everything possible to reduce noise. But by 2017 we found ourselves running up against a <a href="https://doi.org/10.1103/PhysRevLett.118.061302">fundamental minimum noise limit</a> because of a law of quantum physics known as <a href="https://theconversation.com/explainer-heisenbergs-uncertainty-principle-7512">the uncertainty principle</a>.</p>
<p>The uncertainty principle states that it is impossible to know the exact values of certain physical quantities simultaneously – for instance, you can’t know both the position and the momentum of a particle at the same time. Recall that axion detectors search for the axion by measuring two quadratures – those specific kinds of electromagnetic field oscillations. The uncertainty principle prohibits precise knowledge of both quadratures by adding a minimum amount of noise to the quadrature oscillations. </p>
<p>In conventional axion detectors, the quantum noise from the uncertainty principle obscures both quadratures equally. This noise can’t be eliminated, but with the right tools it can be controlled. Our team worked out a way to shuffle around the quantum noise in the HAYSTAC detector, reducing its effect on one quadrature while increasing its effect on the other. This noise manipulation technique is called <a href="https://doi.org/10.1063/PT.3.2596">quantum squeezing</a>.</p>
<p>In an effort led by graduate students <a href="https://scholar.google.com/citations?user=drxpkxYAAAAJ&hl=en">Kelly Backes</a> and <a href="https://scholar.google.com/citations?user=biAydFcAAAAJ&hl=en">Dan Palken</a>, the HAYSTAC team took on the challenge of implementing squeezing in our detector, using superconducting circuit technology borrowed from quantum computing research. General-purpose quantum computers remain <a href="https://theconversation.com/hype-and-cash-are-muddying-public-understanding-of-quantum-computing-82647">a long way off</a>, but our new paper shows that this squeezing technology can immediately speed up the search for dark matter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Shiny gold pipes and technology that surround the detector." src="https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/383394/original/file-20210209-23-qwu6w.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cryogenic cooling helps reduce noise, but by squeezing quantum noise, the HAYSTAC detector can search for an axion signal even faster.</span>
<span class="attribution"><span class="source">Kelly Backes</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Bigger bandwidth, faster search</h2>
<p>Our team succeeded in squeezing the noise in the HAYSTAC detector. But how did we use this to speed up the axion search?</p>
<p>Quantum squeezing doesn’t reduce the noise uniformly across the axion detector bandwidth. Instead, it has the <a href="https://doi.org/10.1103/PhysRevX.9.021023">largest effect at the edges</a>. Imagine you tune your radio to 88.3 megahertz, but the station you want is actually at 88.1. With quantum squeezing, you would be able to hear your favorite song playing one station away. </p>
<p>In the world of radio broadcasting this would be a recipe for disaster, because different stations would interfere with one another. But with only one dark matter signal to look for, a wider bandwidth allows physicists to search faster by covering more frequencies at once. In our latest result we used squeezing to <a href="https://www.nature.com/articles/s41586-021-03226-7">double the bandwidth of HAYSTAC</a>, allowing us to search for axions twice as fast as we could before.</p>
<p>Quantum squeezing alone isn’t enough to scan through every possible axion frequency in a reasonable time. But doubling the scan rate is a big step in the right direction, and we believe further improvements to our quantum squeezing system may enable us to scan 10 times faster.</p>
<p>Nobody knows whether axions exist or whether they will resolve the mystery of dark matter; but thanks to this unexpected application of quantum technology, we’re one step closer to answering these questions.</p><img src="https://counter.theconversation.com/content/153604/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Benjamin Brubaker is a collaborator on the HAYSTAC experiment, which has received funding from the National Science Foundation, the Department of Energy, and the Heising-Simons Foundation.</span></em></p>Researchers have found a way to speed up the search for dark matter using technology from quantum computing. By squeezing quantum noise, detectors can now look for axions twice as fast.Benjamin Brubaker, Postdoctoral Fellow in Quantum Physics, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1474362020-10-26T18:46:49Z2020-10-26T18:46:49ZReimagining the laser: new ideas from quantum theory could herald a revolution<figure><img src="https://images.theconversation.com/files/361830/original/file-20201006-20-k5owis.jpg?ixlib=rb-1.1.0&rect=0%2C617%2C1346%2C1068&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Original artwork by Ludmila Odintsova</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Lasers were created 60 years ago this year, when three different laser devices were unveiled by independent laboratories in the United States. A few years later, one of these inventors called the unusual light sources “<a href="https://www.nytimes.com/1964/05/06/archives/developer-of-the-laser-calls-it-a-solution-seeking-a-problem.html">a solution seeking a problem</a>”. Today, the laser has been applied to countless problems in science, medicine and everyday technologies, with a market of more than <a href="https://www.photonics.com/Articles/A_History_of_the_Laser_1960_-_2019/a42279">US$11 billion</a> per year.</p>
<p>A crucial difference between lasers and <a href="https://arxiv.org/abs/1510.04805">traditional sources of light</a> is the “temporal coherence” of the light beam, or just coherence. The coherence of a beam can be measured by a number <em>C</em>, which takes into account the fact light is <a href="https://theconversation.com/explainer-what-is-wave-particle-duality-7414">both a wave and a particle</a>.</p>
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<em>
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Read more:
<a href="https://theconversation.com/explainer-what-is-wave-particle-duality-7414">Explainer: what is wave-particle duality</a>
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<p>From even before lasers were created, physicists thought they knew exactly how coherent a laser could be. Now, two new studies (one by myself and colleagues in Australia, the other by a team of American physicists) have shown <em>C</em> can be much greater than was previously thought possible. </p>
<h2>How coherent can a laser get?</h2>
<p>The coherence <em>C</em> is roughly the number of photons (particles of light) emitted consecutively into the beam with the same phase (all waving together). For typical lasers, <em>C</em> is very large. Billions of photons are emitted into the beam, all waving together.</p>
<p>This high degree of coherence is what makes lasers suitable for high-precision applications. For example, in many <a href="https://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">quantum computers</a>, we will need a highly coherent beam of light at a specific frequency to control a large number of <a href="https://theconversation.com/double-or-nothing-could-quantum-computing-replace-moores-law-362">qubits</a> over a long period of time. Future quantum computers may need light sources with even greater coherence.</p>
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Read more:
<a href="https://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">Explainer: quantum computation and communication technology </a>
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<p>Physicists have long thought the maximum possible coherence of a laser was governed by an iron rule known as the Schawlow-Townes limit. It is named after the two American physicists who derived it <a href="https://journals.aps.org/pr/abstract/10.1103/PhysRev.112.1940">theoretically in 1958</a> and went on to win Nobel prizes for their laser research. They stated that the coherence <em>C</em> of the beam cannot be greater than the square of <em>N</em>, the number of energy-excitations inside the laser itself. (These excitations could be photons, or they could be atoms in an excited state, for example.)</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/364934/original/file-20201022-19-mxv0j2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/364934/original/file-20201022-19-mxv0j2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/364934/original/file-20201022-19-mxv0j2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/364934/original/file-20201022-19-mxv0j2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/364934/original/file-20201022-19-mxv0j2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/364934/original/file-20201022-19-mxv0j2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/364934/original/file-20201022-19-mxv0j2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Laser beams contain huge numbers of photons all waving together.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Laser#/media/File:Lasers.JPG">Peng Jiajie / Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Raising the limit</h2>
<p>Now, however, two theory papers have appeared that overturn the Schawlow-Townes limit by reimagining the laser. Basically, Schawlow and Townes made assumptions about how energy is added to the laser (gain) and how it is released to form the beam (loss). </p>
<p>The assumptions made sense at the time, and still apply to lasers built today, but they are not required by quantum mechanics. With the amazing advances that have occurred in quantum technology in the past decade or so, our imagination need not be limited by standard assumptions. </p>
<p>The first paper, published this week in <a href="https://www.nature.com/articles/s41567-020-01049-3">Nature Physics</a>, is by my group at Griffith University and a collaborator at Macquarie University. We introduced a new model, which differs from a standard laser in both gain and loss processes, for which the coherence <em>C</em> is as big as <em>N</em> to the fourth power. </p>
<p>In a laser containing as many photons as a regular laser, this would allow <em>C</em> to be much bigger than before. Moreover, we show a laser of this kind could in principle be built using the technology of superconducting qubits and circuits which is used in the currently <a href="https://theconversation.com/why-are-scientists-so-excited-about-a-recently-claimed-quantum-computing-milestone-124082">most successful quantum computers</a>.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-are-scientists-so-excited-about-a-recently-claimed-quantum-computing-milestone-124082">Why are scientists so excited about a recently claimed quantum computing milestone?</a>
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<p>The second paper, by a team at the University of Pittsburgh, has not yet been published in a peer-reviewed journal but recently appeared on the physics <a href="https://arxiv.org/abs/2009.03333">preprint archive</a>. These authors use a somewhat different approach, and end up with a model in which <em>C</em> increases like <em>N</em> to the third power. This group also propose building their laser using superconducting devices. </p>
<p>It is important to note that, in both cases, the laser would not produce a beam of visible light, but rather microwaves. But, as the authors of this second paper note explicitly, this is exactly the type of source required for superconducting quantum computing.</p>
<h2>Can we get even higher?</h2>
<p>The standard limit is that <em>C</em> is proportional to <em>N</em> ², the Pittsburgh group achieved <em>C</em> proportional to <em>N</em> ³, and our model has <em>C</em> proportional to <em>N</em> ⁴. Could some other model achieve an even higher coherence? </p>
<p>No, at least not if the laser beam has the ideal coherence properties we expect from a laser beam. This is another of the results proven in our Nature Physics paper. Coherence proportional to the fourth power of the number of photons is the best that quantum mechanics allows, and we believe it is physically achievable. </p>
<p>An ultimate achievable limit that surpasses what is achievable with standard methods, is known as a Heisenberg limit. This is because it is related to <a href="https://theconversation.com/explainer-heisenbergs-uncertainty-principle-7512">Heisenberg’s uncertainty principle</a>. </p>
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<p>
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Read more:
<a href="https://theconversation.com/explainer-heisenbergs-uncertainty-principle-7512">Explainer: Heisenberg’s Uncertainty Principle</a>
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<p>A Heisenberg-limited laser, as we call it, would not be just a revolution in the design and performance of lasers. It also requires a fundamental rethinking of what a laser is: not restricted to the current kinds of devices, but any device which turns inputs with little coherence into an output of very high coherence. </p>
<p>It is the nature of revolutions that it is impossible to tell whether they will succeed when they begin. But if this one does, and standard lasers are supplanted by Heisenberg-limited lasers, at least in some applications, then these two papers will be remembered as the first shots.</p><img src="https://counter.theconversation.com/content/147436/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Howard Wiseman receives funding from the Australian Research Council. </span></em></p>For 60 years, physicists thought they knew exactly how coherent a laser could get. Now the ultimate quantum limit to laser coherence has been found, and it’s much much bigger than anybody thought.Howard Wiseman, Director, Centre for Quantum Dynamics, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.