tag:theconversation.com,2011:/au/topics/electrons-432/articles
Electrons – The Conversation
2023-10-05T10:02:21Z
tag:theconversation.com,2011:article/214991
2023-10-05T10:02:21Z
2023-10-05T10:02:21Z
I helped select the Nobel laureates in physics – here’s how our committee decides
<figure><img src="https://images.theconversation.com/files/552071/original/file-20231004-27-5j7ipt.jpeg?ixlib=rb-1.1.0&rect=47%2C104%2C1949%2C1221&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The author, Mats Larsson, on the right during the 2023 announcement.</span> <span class="attribution"><span class="source">Kungliga Vetenskapsakademin</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>I am serving my ninth and final year in the <a href="https://www.nobelprize.org/about/the-nobel-committee-for-physics/">Nobel Committee for Physics</a>, which is an absolutely fascinating job – albeit hard. The best bit is hearing the reactions of the shocked laureates when they receive some of the biggest news of their lives over the phone.</p>
<p>Sometimes, I also give presentations about how Nobel laureates are selected. This can be in front of participants in a Nobel symposium, or in front of a high school class. And I have noticed that, while the topic tends to generate great interest, the process is poorly understood. </p>
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Read more:
<a href="https://theconversation.com/nobel-prize-in-physics-awarded-for-work-unveiling-the-secrets-of-electrons-214880">Nobel prize in physics awarded for work unveiling the secrets of electrons</a>
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<p>Explaining how the laureates are selected isn’t entirely straightforward, however – there are strict rules of secrecy. I have to rely on material taken from the official website of the Nobel prize on the one hand, and case studies that are older than 50 years and therefore no longer secret on the other.</p>
<p>The Nobel Committee consists of about six to eight members appointed by the <a href="https://www.kva.se/en/">Royal Swedish Academy of Sciences</a>. The work to select a prize is divided into three parts. The first and very important part is the nominations. The committee sends out about 3,000 letters to researchers all over the world each September and October asking for nominations, with a deadline of January 31 the following year. </p>
<p>The list of nominees is regulated so that certain people are always consulted, including former Nobel laureates, professors of physics in the Nordic countries, and members of the Royal Swedish Academy of Sciences.</p>
<p>Then there is quite a large other group of people who are invited to make nominations but only for a few years at a time, so this part of the process is rotated regularly. Finally, many universities are asked to consult some faculty for their nomination, and once again the universities are rotated.</p>
<p>The second part involves expert reports. Based on the nominations, the committee identifies certain areas of physics where discoveries or inventions have occurred at a level that may make them eligible for an award. </p>
<p>The committee then solicits confidential reports from experts in these chosen areas, who are asked whether they regard these discoveries or inventions of sufficient importance to motivate a Nobel prize. If they do, they are also asked to identify the individuals they consider have made the most important contributions.</p>
<p>The final part is the work done by the committee. At the beginning of June, the committee meets and puts together a shortlist of the most interesting prize candidates. The discussions in the committee are always open, sharp, frank and sometimes emotional, but never hostile.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of Einstein." src="https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552295/original/file-20231005-17-rxez58.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&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">Albert Einstein did not win the Nobel prize for his theory of relativity.</span>
<span class="attribution"><span class="source">wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>In the early 1920s, for example, there was enormous pressure to award Albert Einstein. But some members of the committee were sceptical about the theory of relativity. The compromise was to award Einstein for the explanation of a phenomenon called <a href="https://www.nobelprize.org/prizes/physics/1921/summary/">the photoelectric effect</a> instead, which is exactly the effect <a href="https://theconversation.com/nobel-prize-in-physics-awarded-for-work-unveiling-the-secrets-of-electrons-214880">this year’s laureates</a> have investigated in great detail. </p>
<p>Amazingly, while the other successful theory of modern physics, quantum mechanics, has been richly awarded with Nobel prizes (1932/33, 1945, 1954, 2022), it took until 2020 for the theory of relativity <a href="https://www.nobelprize.org/prizes/physics/2020/penrose/facts/">to be awarded explicitly</a>.</p>
<h2>Final stages</h2>
<p>During the summer, each committee member works on their own to prepare certain sections of the final prize report. During a retreat in August, the committee meets and finalises this report, with a recommendation to the Royal Swedish Academy of Sciences. There are actually several meetings between committee members during the summer months, but contact by email and telephone is strictly forbidden. </p>
<p>The report, including a suggestion for a maximum of three laureates and a citation, is then sent to the academy. In September, the suggestion is discussed among the physics members of the academy. During a second September meeting, this group takes a vote on whether it supports the suggestion from the committee. </p>
<p>In October, on the same day the prize is announced, the academy meets again to make a final decision, which cannot be appealed. Once the decision has been taken, the laureates are contacted by telephone. Finally, the decision is announced at a press conference that is broadcast live on Swedish public TV and on the academy’s homepage. </p>
<p>The day after the announcement, a few of the committee members start helping with the poster that will be freely available to the public in connection with the Nobel lectures in December. </p>
<p>By now, the work on next year’s Nobel prize in Physics has already started – even before this year’s nominations were known. There are always expert reports that are discussed and solicited. The work never stops!</p><img src="https://counter.theconversation.com/content/214991/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mats Larsson receives funding from Vetenskapsrådet (VR) and has previously been funded by Naturvetenskapliga forskningsrådet (NFR).</span></em></p>
The discussions in the committee are always open, frank and sometimes emotional, but never hostile.
Mats Larsson, Professor of molecular physics, Stockholm University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/214931
2023-10-04T12:33:56Z
2023-10-04T12:33:56Z
Making ‘movies’ at the attosecond scale helps researchers better understand electrons − and could one day lead to super-fast electronics
<figure><img src="https://images.theconversation.com/files/551941/original/file-20231004-25-lxu197.png?ixlib=rb-1.1.0&rect=172%2C12%2C2703%2C1090&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Attosecond light pulses help researchers understand the movement of electrons. </span> <span class="attribution"><a class="source" href="https://www6.slac.stanford.edu/news/2022-01-27-researchers-use-attosecond-x-ray-pulses-track-electron-motion-highly-excited">Greg Stewart/SLAC National Accelerator Laboratory</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Electrons moving around in a molecule might not seem like the plot of an interesting movie. But a group of scientists will receive the <a href="https://www.nobelprize.org/prizes/physics/2023/press-release/">2023 Nobel Prize in physics</a> for research that essentially <a href="https://theconversation.com/nobel-prize-in-physics-prize-awarded-for-work-unveiling-the-secrets-of-electrons-214880">follows the movement of electrons</a> using ultrafast laser pulses, like capturing frames in a video camera. </p>
<p>However, electrons, which partly <a href="https://www.britannica.com/science/electron">make up atoms</a> and form the glue that bonds atoms in molecules together, don’t move around on the same time scale people do. They’re much faster. So, the tools that <a href="https://scholar.google.com/citations?user=fO8mIS8AAAAJ&hl=en">physicists like me</a> use to capture their motion have to be really fast – attosecond-scale fast.</p>
<p><a href="https://www.nrel.gov/comm-standards/editorial/scientific-notation.html">One attosecond</a> is one billionth of a billionth of a second (10<sup>-18</sup> second) – the ratio of one attosecond to one second is the same as the ratio of one second to the age of the universe. </p>
<h2>Attosecond pulses</h2>
<p>In photography, capturing clear images of fast objects requires a camera with a <a href="https://www.britannica.com/technology/shutter-photography">fast shutter</a> or a fast strobe of light to illuminate the object. By taking multiple photos in quick succession, the motion of the object can be clearly resolved.</p>
<p>The time scale of the shutter or the strobe must match the time scale of motion of the object – if not, the image will be blurred. This same idea applies when researchers attempt to <a href="https://www.nobelprize.org/uploads/2023/10/advanced-physicsprize2023.pdf">image the ultrafast motion of electrons</a>. Capturing attosecond-scale motion requires an attosecond strobe. The 2023 <a href="https://www.nobelprize.org/prizes/physics/2023/press-release/">Nobel laureates in physics</a> made seminal contributions to the generation of such attosecond laser strobes, which are very short pulses generated using a powerful laser.</p>
<p>Imagine the electrons in an atom are constrained within the atom by a wall. When a femtosecond (10<sup>-15</sup> second) laser pulse from a high-powered femtosecond laser is directed at atoms of a noble gas such as argon, the strong electric field in the pulse lowers the wall.</p>
<p>This is possible because the laser electric field is comparable in strength to the electric field of the nucleus of the atom. Electrons see this lowered wall and pass through in a bizarre process called <a href="https://theconversation.com/we-did-a-breakthrough-speed-test-in-quantum-tunnelling-and-heres-why-thats-exciting-113761">quantum tunneling</a>. </p>
<p>As soon as the electrons exit the atom, the laser’s electric field captures them, accelerates them to high energies and slams them back into their parent atoms. This process of recollision results in creation of attosecond bursts of laser light.</p>
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<a href="https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing how electrons gain, then release energy when exposed to a laser's electric field, with a pink arrow showing the laser's energy and small drawings of spheres stuck together indicating the atom." src="https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551903/original/file-20231003-29-34udqs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A laser’s electric field allows electrons to escape from the atom, gain energy and then release energy as they’re reabsorbed back into the atom.</span>
<span class="attribution"><a class="source" href="https://www.nobelprize.org/prizes/physics/2023/press-release/">Johan Jarnestad/The Royal Swedish Academy of Sciences</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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</figure>
<h2>Attosecond movies</h2>
<p>So how do physicists use these ultrashort pulses to make movies of electrons at the attosecond scale?</p>
<p>Conventional movies are made one scene at a time, with each instant captured as a frame with video cameras. The scenes are then stitched together to form the complete movie. </p>
<p>Attosecond movies of electrons use a similar idea. The attosecond pulses act as strobes, lighting up the electrons so researchers can capture their image, over and over again as they move – like a movie scene. This technique is called <a href="https://web.mit.edu/gediklab/research.html">pump-probe spectroscopy</a>.</p>
<p>However, imaging electron motion directly inside atoms is currently challenging, though researchers are developing several approaches using advanced microscopes to <a href="https://doi.org/10.1038/nphoton.2017.97">make direct imaging possible</a>. </p>
<p>Typically, in pump-probe spectroscopy, a “pump” pulse gets the electron moving and starts the movie. A “probe” pulse then lights up the electron at different times after the arrival of the pump pulse, so it can be captured by the “camera,” such as a <a href="https://en.wikipedia.org/wiki/Photoemission_spectroscopy">photoelectron spectrometer</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/Vy71bJJ9EnU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Pump-probe spectroscopy.</span></figcaption>
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<p>The information on the motion of electrons, or the “image,” is captured using sophisticated techniques. For example, a photoelectron spectrometer detects how many electrons were removed from the atom by the probe pulse, or a <a href="https://en.wikipedia.org/wiki/Spectrometer">photon spectrometer</a> measures how much of the probe pulse was absorbed by the atom.</p>
<p>The different “scenes” are then stitched together to make the attosecond movies of electrons. These movies help provide fundamental insight, with help from <a href="https://doi.org/10.1002/wcms.1673">sophisticated theoretical models</a>, into attosecond electronic behavior. </p>
<p>For example, researchers have measured <a href="https://doi.org/10.1126/science.aab2160">where the electric charge is located</a> in organic molecules at different times, on attosecond time scales. This could allow them to control electric currents on the molecular scale.</p>
<h2>Future applications</h2>
<p>In most scientific research, fundamental understanding of a process leads to control of the process, and such control leads to new technologies. <a href="https://theconversation.com/tenacious-curiosity-in-the-lab-can-lead-to-a-nobel-prize-mrna-research-exemplifies-the-unpredictable-value-of-basic-scientific-research-214770">Curiosity-driven research</a> can lead to unimaginable applications in the future, and attosecond science is likely no different. </p>
<p>Understanding and controlling the behavior of electrons on the attosecond scale could enable researchers to use <a href="https://doi.org/10.1021/acsomega.0c02098">lasers to control chemical reactions</a> that they can’t by other means. This ability could help engineer new molecules that cannot be created with existing chemical techniques.</p>
<p>The ability to modify electron behavior could lead to ultrafast switches. Researchers could potentially convert an <a href="https://www.mpg.de/6694490/light-frequencies-electronics">electric insulator to a conductor on attosecond scales</a> to increase the speed of electronics. Electronics currently process information at the picosecond scale, or 10<sup>-12</sup> of a second. </p>
<p>The short wavelength of attosecond pulses, which is typically in the extreme-ultraviolet, or EUV, regime, may see applications in <a href="https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithography">EUV lithography</a> in the semiconductor industry. EUV lithography uses laser light with a very short wavelength to etch tiny circuits on electronic chips.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A line of silver pipes and machinery, in a bright room, with red and blue handles." src="https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=240&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=240&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=240&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=302&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=302&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551901/original/file-20231003-25-g5a55f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=302&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 Linac Coherent Light Source at SLAC National Accelerator Laboratory.</span>
<span class="attribution"><a class="source" href="https://science.osti.gov/bes/suf/User-Facilities/X-Ray-Light-Sources/LCLS">Department of Energy</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In the recent past, free-electron lasers such as the <a href="https://lcls.slac.stanford.edu/">Linac Coherent Light Source</a> at SLAC National Accelerator Laboratory in the United States have emerged as a source of bright X-ray laser light. These now generate pulses on the attosecond scale, opening many possibilities for research using attosecond X-rays.</p>
<p>Ideas to generate laser pulses on the zeptosecond (10<sup>-21</sup> second) scale have also been proposed. Scientists could use these pulses, which are even faster than attosecond pulses, to study the motion of particles like protons within the nucleus. </p>
<p>With numerous research groups actively working on exciting problems in attosecond science, and with <a href="https://www.nobelprize.org/prizes/physics/2023/press-release/">2023’s Nobel Prize in physics</a> recognizing its importance, attosecond science has a long and bright future.</p><img src="https://counter.theconversation.com/content/214931/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Niranjan Shivaram receives funding from the National Science Foundation and U.S. Department of Energy. </span></em></p>
The 2023 Nobel Prize in physics recognized researchers studying electron movement in real time − this work could revolutionize electronics, laser imaging and more.
Niranjan Shivaram, Assistant Professor of Physics and Astronomy, Purdue University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/214907
2023-10-04T01:42:55Z
2023-10-04T01:42:55Z
What is an attosecond? A physical chemist explains the tiny time scale behind Nobel Prize-winning research
<figure><img src="https://images.theconversation.com/files/551866/original/file-20231003-27-fn9thz.jpg?ixlib=rb-1.1.0&rect=10%2C3%2C2295%2C1292&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Work in attosecond physics has led to a better understanding of how electrons move around. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/image-of-an-atomic-structure-consisting-of-protons-royalty-free-image/1337003441?phrase=electron">Oselote/iStock via Getty Images</a></span></figcaption></figure><p>A group of three researchers earned the <a href="https://www.nobelprize.org/uploads/2023/10/popular-physicsprize2023.pdf">2023 Nobel Prize in physics</a> for work that has revolutionized how scientists study the electron – by illuminating molecules with attosecond-long flashes of light. But how long is an attosecond, and what can these infinitesimally short pulses tell researchers about the nature of matter?</p>
<p><a href="https://www.austincollege.edu/aaron-harrison/">I first learned</a> of this area of research as a graduate student in physical chemistry. My doctoral adviser’s group had a project dedicated to studying <a href="http://bromine.cchem.berkeley.edu/atto.htm">chemical reactions with attosecond pulses</a>. Before understanding why attosecond research resulted in the most prestigious award in the sciences, it helps to understand what an attosecond pulse of light is.</p>
<h2>How long is an attosecond?</h2>
<p>“Atto” is the <a href="https://www.nrel.gov/comm-standards/editorial/scientific-notation.html">scientific notation prefix</a> that represents 10<sup>-18</sup>, which is a decimal point followed by 17 zeroes and a 1. So a flash of light lasting an attosecond, or 0.000000000000000001 of a second, is an extremely short pulse of light. </p>
<p>In fact, there are approximately as many attoseconds in one second as there are seconds in the <a href="https://81018.com/universeclock/">age of the universe</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing an attosecond, depicted as an orange collection of hexagons, on the left, with the age of the universe, depicted as a dark vacuum on the right, and a heartbeat, depicted as a human heart, in the middle." src="https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=256&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=256&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=256&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=322&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=322&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551859/original/file-20231003-21-rkpekw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=322&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An attosecond is incredibly small when compared to a second.</span>
<span class="attribution"><a class="source" href="https://www.nobelprize.org/prizes/physics/2023/press-release/">©Johan Jarnestad/The Royal Swedish Academy of Sciences</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Previously, scientists could study the motion of heavier and slower-moving atomic nuclei with <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/femtosecond-laser">femtosecond (10<sup>-15</sup>) light pulses</a>. One thousand attoseconds are in 1 femtosecond. But researchers couldn’t see movement on the electron scale until they could generate attosecond light pulses – electrons move too fast for scientists to parse exactly what they are up to at the femtosecond level.</p>
<h2>Attosecond pulses</h2>
<p>The rearrangement of electrons in atoms and molecules guides a lot of processes in physics, and it underlies practically every part of chemistry. Therefore, researchers have put a lot of effort into figuring out how electrons are moving and rearranging. </p>
<p>However, electrons move around very rapidly in physical and chemical processes, making them difficult to study. To investigate these processes, <a href="https://www.britannica.com/science/spectroscopy">scientists use spectroscopy</a>, a method of examining how matter absorbs or emits light. In order to <a href="https://doi.org/10.1146/annurev-physchem-040215-112025">follow the electrons in real time</a>, researchers need a pulse of light that is shorter than the time it takes for electrons to rearrange. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Vy71bJJ9EnU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Pump-probe spectroscopy is a common technique in physics and chemistry and can be performed with attosecond light pulses.</span></figcaption>
</figure>
<p>As an analogy, imagine a camera that could only take longer exposures, around 1 second long. Things in motion, like a person running toward the camera or a bird flying across the sky, would appear blurry in the photos taken, and it would be difficult to see exactly what was going on. </p>
<p>Then, imagine you use a camera with a 1 millisecond exposure. Now, motions that were previously smeared out would be nicely resolved into clear and precise snapshots. That’s how using the attosecond scale, rather than the femtosecond scale, can illuminate electron behavior. </p>
<h2>Attosecond research</h2>
<p>So what kind of research questions can attosecond pulses help answer?</p>
<p>For one, breaking a chemical bond is a fundamental process in nature where electrons that are shared between two atoms separate out into unbound atoms. The previously shared electrons undergo ultrafast changes during this process, and <a href="https://doi.org/10.1126/science.aax0076">attosecond pulses</a> made it possible for researchers to follow the real-time breaking of a chemical bond. </p>
<p>The <a href="https://doi.org/10.1038/nphys620">ability to generate attosecond pulses</a> – the research for which three researchers earned the <a href="https://www.nobelprize.org/prizes/physics/2023/press-release/">2023 Nobel Prize in physics</a> – first became possible in the early 2000s, and the field has <a href="https://phys.org/news/2010-04-electrons-science-attosecond-scale.html">continued to grow rapidly</a> since. By providing shorter snapshots of atoms and molecules, attosecond spectroscopy has helped researchers understand electron behavior in single molecules, such as how <a href="https://doi.org/10.1038/s41467-022-32313-0">electron charge migrates</a> and how <a href="https://doi.org/10.1063/5.0086775">chemical bonds</a> between atoms break. </p>
<p>On a larger scale, attosecond technology has also been applied to studying how electrons behave in <a href="https://doi.org/10.1126/science.abb0979">liquid water</a> as well as <a href="https://doi.org/10.1038/s42005-021-00635-y">electron transfer in solid-state semiconductors</a>. As researchers continue to improve their ability to produce attosecond light pulses, they’ll gain a deeper understanding of the basic particles that make up matter.</p><img src="https://counter.theconversation.com/content/214907/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aaron W. Harrison 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>
Three scientists won the 2023 Nobel Prize in physics for their work developing methods to shoot laser pulses that only last an attosecond, or a mind-bogglingly tiny fraction of a second.
Aaron W. Harrison, Assistant Professor of Chemistry, Austin College
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205820
2023-06-27T12:23:57Z
2023-06-27T12:23:57Z
The digital future may rely on ultrafast optical electronics and computers
<figure><img src="https://images.theconversation.com/files/532461/original/file-20230616-23761-r0m0kq.jpeg?ixlib=rb-1.1.0&rect=38%2C15%2C1683%2C1239&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The author's lab's ultrafast optical switch in action.</span> <span class="attribution"><span class="source">Mohammed Hassan, University of Arizona</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>If you’ve ever wished you had a faster phone, computer or internet connection, you’ve encountered the personal experience of hitting a limit of technology. But there might be help on the way.</p>
<p>Over the past several decades, scientists and engineers <a href="https://scholar.google.com/citations?user=JA0qsY0AAAAJ&hl=en&oi=ao">like me</a> have worked to develop faster transistors, the electronic components underlying modern electronic and digital communications technologies. These efforts have been based on a category of materials called semiconductors that have special electrical properties. <a href="https://doi.org/10.1038/483S43a">Silicon</a> is perhaps the best known example of this type of material. </p>
<p>But about a decade ago, scientific efforts hit the speed limit of semiconductor-based transistors. Researchers simply can’t make electrons move faster through these materials. One way engineers are trying to address the speed limits inherent in moving a current through silicon is to design shorter physical circuits – essentially giving electrons less distance to travel. Increasing the computing power of a chip comes down to increasing the number of transistors. However, even if researchers are able to get transistors to be very small, they won’t be fast enough for the faster processing and data transfer speeds people and businesses will need.</p>
<p>My <a href="https://hassan.lab.arizona.edu">research group’s work</a> aims to develop faster ways to move data, using ultrafast laser pulses in free space and optical fiber. The laser light travels through optical fiber with almost no loss and with a very low level of noise.</p>
<p>In our most recent study, published in February 2023 in Science Advances, we took a step toward that, demonstrating that it’s possible to use <a href="https://doi.org/10.1126/sciadv.adf1015">laser-based systems</a> equipped with optical transistors, which depend on photons rather than voltage to move electrons, and to transfer information much more quickly than current systems – and do so more effectively than <a href="https://doi.org/10.1038/s41586-021-03866-9">previously reported optical switches</a>.</p>
<h2>Ultrafast optical transistors</h2>
<p>At their most fundamental level, digital transmissions involve a signal switching on and off to represent ones and zeros. Electronic transistors use voltage to send this signal: When the voltage induces the electrons to flow through the system, they signal a 1; when there are no electrons flowing, that signals a 0. This requires a source to emit the electrons and a receiver to detect them. </p>
<p>Our system of ultrafast optical data transmission is based on light rather than voltage. Our research group is one of many working with optical communication at the transistor level – the building blocks of modern processors – to get around the current limitations with silicon. </p>
<p>Our system controls reflected light to transmit information. When light shines on a piece of glass, most of it passes through, though a little bit might reflect. That is what you experience as glare when driving toward sunlight or looking through a window.</p>
<p>We use two laser beams transmitted from two sources passing through the same piece of glass. One beam is constant, but its transmission through the glass is controlled by the second beam. By using the second beam to shift the properties of the glass from transparent to reflective, we can start and stop the transmission of the constant beam, switching the optical signal from on to off and back again very quickly. </p>
<p>With this method, we can switch the glass properties much more quickly than current systems can send electrons. So we can send many more on and off signals – zeros and ones – in less time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a hand holds a bundle of optical fibers between thumb and first finger" src="https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=441&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=441&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=441&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=554&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=554&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534180/original/file-20230626-1803-19w9pt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=554&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 author’s research group has developed a way to switch light beams on and off, like those passing through these optical fibers, 1 million billion times a second.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/bundle-of-light-wave-cables-fibre-optic-news-photo/976186008">Mediacolors/Construction Photography/Avalon via Getty Images</a></span>
</figcaption>
</figure>
<h2>How fast are we talking?</h2>
<p>Our study took the first step to transmitting data 1 million times faster than if we had used the typical electronics. With electrons, the maximum speed for transmitting data is a <a href="https://www.wolframalpha.com/input?i=nanosecond">nanosecond</a>, one-billionth of a second, which is very fast. But the optical switch we constructed was able to transmit data a million times faster, which took just a few hundred <a href="https://www.wolframalpha.com/input?i=attosecond">attoseconds</a>.</p>
<p>We were also able to transmit those signals securely so that an attacker who tried to intercept or modify the messages would fail or be detected. </p>
<p>Using a laser beam to carry a signal, and adjusting its signal intensity with glass controlled by another laser beam, means the information can travel not only more quickly but also much greater distances. </p>
<p>For instance, the James Webb Space Telescope recently transmitted <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-explains-the-stunning-newly-released-first-images-186800">stunning images from far out in space</a>. These pictures were transferred as data from the telescope to the base station on Earth at a rate of one “on” or “off” <a href="https://webbtelescope.org/quick-facts">every 35 nanosconds</a> using optical communications.</p>
<p>A laser system like the one we’re developing could speed up the transfer rate a billionfold, allowing faster and clearer exploration of deep space, more quickly revealing the universe’s secrets. And someday computers themselves might run on light.</p><img src="https://counter.theconversation.com/content/205820/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mohammed Hassan receives funding from the Gordon and Betty Moore Foundation and the Air Force Office of Scientific Research.</span></em></p>
A researcher explains developments in using light rather than electrons to transmit information securely and quickly, even over long distances.
Mohammed Hassan, Associate Professor of Physics and Optical Sciences, University of Arizona
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/204995
2023-05-15T12:33:56Z
2023-05-15T12:33:56Z
Quantum physics proposes a new way to study biology – and the results could revolutionize our understanding of how life works
<figure><img src="https://images.theconversation.com/files/525487/original/file-20230510-21-cnx7u8.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1999%2C1499&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Looking at life at the atomic scale offers a more comprehensive understanding of the macroscopic world.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/colorful-model-of-helix-dna-strand-royalty-free-image/157531306">theasis/E+ via Getty Images</a></span></figcaption></figure><p>Imagine using your cellphone to control the activity of your own cells to treat injuries and disease. It sounds like something from the imagination of an overly optimistic science fiction writer. But this may one day be a possibility through the emerging field of quantum biology.</p>
<p>Over the past few decades, scientists have made incredible progress in understanding and manipulating biological systems at increasingly small scales, from <a href="https://theconversation.com/when-researchers-dont-have-the-proteins-they-need-they-can-get-ai-to-hallucinate-new-structures-173209">protein folding</a> to <a href="https://www.genome.gov/genetics-glossary/Genetic-Engineering">genetic engineering</a>. And yet, the extent to which quantum effects influence living systems remains barely understood.</p>
<p>Quantum effects are phenomena that occur between atoms and molecules that can’t be explained by classical physics. It has been known for more than a century that the rules of classical mechanics, like Newton’s laws of motion, <a href="https://iopscience.iop.org/book/mono/978-0-7503-1206-6/chapter/bk978-0-7503-1206-6ch1">break down at atomic scales</a>. Instead, tiny objects behave according to a different set of laws known as <a href="https://www.britannica.com/science/quantum-mechanics-physics">quantum mechanics</a>. </p>
<figure>
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<figcaption><span class="caption">Quantum mechanics describes the properties of atoms and molecules.</span></figcaption>
</figure>
<p>For humans, who can only perceive the macroscopic world, or what’s visible to the naked eye, quantum mechanics can seem counterintuitive and somewhat magical. Things you might not expect happen in the quantum world, like <a href="https://theconversation.com/we-did-a-breakthrough-speed-test-in-quantum-tunnelling-and-heres-why-thats-exciting-113761">electrons “tunneling” through</a> tiny energy barriers and appearing on the other side unscathed, or being in two different places at the same time in a <a href="https://scienceexchange.caltech.edu/topics/quantum-science-explained/quantum-superposition">phenomenon called superposition</a>.</p>
<p>I am trained as a <a href="https://scholar.google.com/citations?user=1aqtpo8AAAAJ&hl=en">quantum engineer</a>. Research in quantum mechanics is usually geared toward technology. However, and somewhat surprisingly, there is increasing evidence that nature – an engineer with billions of years of practice – has learned how to <a href="https://royalsociety.org/grants-schemes-awards/book-prizes/science-book-prize/2015/life-on-the-edge/">use quantum mechanics to function optimally</a>. If this is indeed true, it means that our understanding of biology is radically incomplete. It also means that we could possibly control physiological processes by using the quantum properties of biological matter.</p>
<h2>Quantumness in biology is probably real</h2>
<p>Researchers can manipulate quantum phenomena to build better technology. In fact, you already live in a <a href="https://uwaterloo.ca/institute-for-quantum-computing/quantum-101/quantum-applications-today">quantum-powered world</a>: from laser pointers to GPS, magnetic resonance imaging and the transistors in your computer – all these technologies rely on quantum effects.</p>
<p>In general, quantum effects only manifest at very small length and mass scales, or when temperatures approach absolute zero. This is because quantum objects like atoms and molecules <a href="https://www.theatlantic.com/science/archive/2018/10/beyond-weird-decoherence-quantum-weirdness-schrodingers-cat/573448/">lose their “quantumness”</a> when they uncontrollably interact with each other and their environment. In other words, a macroscopic collection of quantum objects is better described by the laws of classical mechanics. Everything that starts quantum dies classical. For example, an electron can be manipulated to be in two places at the same time, but it will end up in only one place after a short while – exactly what would be expected classically.</p>
<figure>
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<figcaption><span class="caption">Electrons can be in two places at the same time, but will end up in one location eventually.</span></figcaption>
</figure>
<p>In a complicated, noisy biological system, it is thus expected that most quantum effects will rapidly disappear, washed out in what the physicist Erwin Schrödinger called the “<a href="https://doi.org/10.1017/CBO9781139644129">warm, wet environment of the cell</a>.” To most physicists, the fact that the living world operates at elevated temperatures and in complex environments implies that biology can be adequately and fully described by classical physics: no funky barrier crossing, no being in multiple locations simultaneously.</p>
<p>Chemists, however, have for a long time begged to differ. Research on basic chemical reactions at room temperature unambiguously shows that <a href="https://doi.org/10.1063/5.0006547">processes occurring within biomolecules</a> like proteins and genetic material are the result of quantum effects. Importantly, such nanoscopic, short-lived quantum effects are consistent with driving some macroscopic physiological processes that biologists have measured in living cells and organisms. Research suggests that quantum effects influence biological functions, including <a href="https://doi.org/10.1146/annurev-biochem-051710-133623">regulating enzyme activity</a>, <a href="https://doi.org/10.1146/annurev-biophys-032116-094545">sensing magnetic fields</a>, <a href="https://doi.org/10.1038/srep38543">cell metabolism</a> and <a href="https://doi.org/10.1038/s41570-019-0087-1">electron transport in biomolecules</a>.</p>
<h2>How to study quantum biology</h2>
<p>The tantalizing possibility that subtle quantum effects can tweak biological processes presents both an exciting frontier and a challenge to scientists. Studying quantum mechanical effects in biology requires tools that can measure the short time scales, small length scales and subtle differences in quantum states that give rise to physiological changes – all integrated within a traditional wet lab environment.</p>
<p><a href="http://www.claricedaiello.com">In my work</a>, I build instruments to study and control the quantum properties of small things like electrons. In the same way that electrons have mass and charge, they also have a <a href="https://www.britannica.com/science/spin-atomic-physics">quantum property called spin</a>. Spin defines how the electrons interact with a magnetic field, in the same way that charge defines how electrons interact with an electric field. The quantum experiments I have been building <a href="https://doi.org/10.1038/ncomms2375">since graduate school</a>, and now in my own lab, aim to apply tailored magnetic fields to change the spins of particular electrons.</p>
<p>Research has demonstrated that many physiological processes are influenced by weak magnetic fields. These processes include <a href="https://doi.org/10.1126/sciadv.aau7201">stem cell development</a> and <a href="https://doi.org/10.1021/nn502923s">maturation</a>, <a href="https://doi.org/10.1371/journal.pone.0054775">cell proliferation rates</a>, <a href="https://doi.org/10.1021/acscentsci.8b00008">genetic material repair</a> and <a href="https://doi.org/10.1371/journal.pone.0179340">countless others</a>. These physiological responses to magnetic fields are consistent with chemical reactions that depend on the spin of particular electrons within molecules. Applying a weak magnetic field to change electron spins can thus effectively control a chemical reaction’s final products, with important physiological consequences.</p>
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<figcaption><span class="caption">Birds use quantum effects in navigation.</span></figcaption>
</figure>
<p>Currently, a lack of understanding of how such processes work at the nanoscale level prevents researchers from determining exactly what strength and frequency of magnetic fields cause specific chemical reactions in cells. Current cellphone, wearable and miniaturization technologies are already sufficient to produce <a href="https://doi.org/10.14814%2Fphy2.15189">tailored, weak magnetic fields that change physiology</a>, both for good and for bad. The missing piece of the puzzle is, hence, a “deterministic codebook” of how to map quantum causes to physiological outcomes.</p>
<p>In the future, fine-tuning nature’s quantum properties could enable researchers to develop therapeutic devices that are noninvasive, remotely controlled and accessible with a mobile phone. Electromagnetic treatments could potentially be used to prevent and treat disease, such as <a href="https://doi.org/10.1038/s41416-020-01136-5">brain tumors</a>, as well as in biomanufacturing, such as <a href="https://doi.org/10.1016/j.biomaterials.2022.121658">increasing lab-grown meat production</a>.</p>
<h2>A whole new way of doing science</h2>
<p>Quantum biology is one of the most interdisciplinary fields to ever emerge. How do you build community and train scientists to work in this area? </p>
<p>Since the pandemic, my lab at the University of California, Los Angeles and the University of Surrey’s Quantum Biology Doctoral Training Centre have organized <a href="https://groups.google.com/u/1/g/bigquantumbiologymeetings">Big Quantum Biology meetings</a> to provide an informal weekly forum for researchers to meet and share their expertise in fields like mainstream quantum physics, biophysics, medicine, chemistry and biology.</p>
<p>Research with potentially transformative implications for biology, medicine and the physical sciences will require working within an equally transformative model of collaboration. Working in one unified lab would allow scientists from disciplines that take very different approaches to research to conduct experiments that meet the breadth of quantum biology from the quantum to the molecular, the cellular and the organismal.</p>
<p>The existence of quantum biology as a discipline implies that traditional understanding of life processes is incomplete. Further research will lead to new insights into the age-old question of what life is, how it can be controlled and how to learn with nature to build better quantum technologies.</p><img src="https://counter.theconversation.com/content/204995/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clarice D. Aiello receives funding from NSF, ONR, IDOR Foundation, Faggin Foundation, Templeton Foundation. </span></em></p>
Studying the brief and tiny quantum effects that drive living systems could one day lead to new approaches to treatments and technologies.
Clarice D. Aiello, Quantum Biology Tech (QuBiT) Lab, Assistant Professor of Electrical and Computer Engineering, University of California, Los Angeles
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/197712
2023-01-17T00:16:42Z
2023-01-17T00:16:42Z
Physicists have used entanglement to ‘stretch’ the uncertainty principle, improving quantum measurements
<figure><img src="https://images.theconversation.com/files/504370/original/file-20230113-14-rc7nuw.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C7000%2C4191&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>Almost a century ago, German physicist Werner Heisenberg realised the laws of quantum mechanics placed some fundamental limits on how accurately we can measure certain properties of microscopic objects. </p>
<p>However, the laws of quantum mechanics can also offer ways to make measurements more accurate than would otherwise be possible.</p>
<p>In new research <a href="https://www.nature.com/articles/s41567-022-01875-7">published in Nature Physics</a>, we have outlined a way to achieve more accurate measurements of microscopic objects using quantum computers. This could prove useful in a huge range of next-generation technologies, including biomedical sensing, laser ranging and quantum communications. </p>
<p>We were also able to push beyond the limits of a variation of Heisenberg’s “uncertainty principle” in certain circumstances, suggesting different uncertainty principles may be necessary in different scenarios.</p>
<h2>Quantum uncertainties</h2>
<p>If you want to examine the properties of a large everyday object like a car, it’s a simple process. </p>
<p>For example, a car has a well-defined position, colour and speed. You can measure them one after another or all at once with no issues. Measuring the position of your car will not change its colour or speed.</p>
<p>However, this becomes much trickier if you’re trying to examine microscopic quantum objects like electrons or photons (which are tiny little particles of light). </p>
<p>Certain properties of quantum objects are connected to each other. Measuring one property can influence another property. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-heisenbergs-uncertainty-principle-7512">Explainer: Heisenberg’s Uncertainty Principle</a>
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</em>
</p>
<hr>
<p>For example, measuring the position of an electron will affect its speed and vice versa. </p>
<p>These properties are called “conjugate” properties. </p>
<p>The link between these properties is a direct manifestation of Heisenberg’s uncertainty principle. It is not possible to simultaneously measure two conjugate properties of a quantum object to whatever degree of accuracy you like: the more you know about one, the less you know about the other.</p>
<p>While the uncertainty principle imposes a limit on how accurate some measurements can be, reaching that limit in practice can be very challenging. However, measuring quantum objects in the greatest amount of detail possible is important for advancing fundamental science as well as developing new technologies. </p>
<h2>Entangled objects</h2>
<p>In our new research, we designed a way to determine conjugate properties of quantum objects more accurately. Our collaborators were then able to carry out this measurement in various labs around the world.</p>
<p>The new technique revolves around a strange quirk of quantum systems, known as entanglement. When two objects are entangled, we can measure them more accurately than if they weren’t entangled.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-quantum-entanglement-a-physicist-explains-the-science-of-einsteins-spooky-action-at-a-distance-191927">What is quantum entanglement? A physicist explains the science of Einstein’s ‘spooky action at a distance’</a>
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<p>We realised we could use quantum computers, which can precisely control the state of quantum objects, to create two identical quantum objects and entangle them. By measuring the entangled objects together, we could determine their properties more precisely than if they were measured individually. </p>
<p>Measuring the two entangled identical quantum objects reduces the noise in the measurement, making it more accurate.</p>
<h2>A less noisy future</h2>
<p>In theory, it is also possible to entangle and measure three or more quantum systems to achieve even better precision. However, we haven’t been able to make this work experimentally as yet. </p>
<p>The results of measuring three identical entangled objects together were very noisy. However, as quantum computers improve and become more accurate, it may be possible to faithfully measure three copies of a quantum system simultaneously in the future.</p>
<figure class="align-center ">
<img alt="An elaborate cooling rig for a quantum computer, against a black background." src="https://images.theconversation.com/files/504371/original/file-20230113-20-t7ufet.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/504371/original/file-20230113-20-t7ufet.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/504371/original/file-20230113-20-t7ufet.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/504371/original/file-20230113-20-t7ufet.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/504371/original/file-20230113-20-t7ufet.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/504371/original/file-20230113-20-t7ufet.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/504371/original/file-20230113-20-t7ufet.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Quantum computers of the future may be less noisy.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>One of the key strengths of this work is that a quantum enhancement can still be observed in very noisy scenarios. This bodes well for future practical applications, such as in biomedical measurements, which will inevitably occur in noisy real-world environments.</p>
<h2>What about the uncertainty principle?</h2>
<p>This research also has implications for the aforementioned uncertainty principle. </p>
<p>One interpretation of the uncertainty principle is that it is impossible to measure conjugate properties of quantum objects with unlimited accuracy. But another interpretation is that measuring one conjugate property of a quantum object must necessarily disturb the second conjugate property by some minimum amount. </p>
<p>In this research, we were able to violate an uncertainty principle based on the second interpretation. This suggests that, depending on what physical setting is considered, different uncertainty principles may be necessary for different scenarios. </p>
<h2>A global collaboration</h2>
<p>We tested our theory on a total of 19 different quantum computers, which used three different quantum computing technologies: superconductors, trapped ions and photonics. These devices are located across Europe and America and can be accessed via the internet, allowing researchers from across the globe to connect and carry out important research.</p>
<p>We carried out the study with colleagues at the ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), in collaboration with researchers from the Institute of Materials Research and Engineering at A*STAR in Singapore, the University of Jena, the University of Innsbruck, Macquarie University and Amazon Web Services.</p><img src="https://counter.theconversation.com/content/197712/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Examining microscopic quantum objects is exceedingly tricky, because their properties are connected to each other. But there could be a new method to measure them as accurately as possible.
Lorcan Conlon, PhD student, Quantum Science & Technology, Australian National University
Syed Assad, Research Associate, Quantum Science & Technology, Australian National University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/184892
2022-07-11T12:30:22Z
2022-07-11T12:30:22Z
What do molecules look like?
<figure><img src="https://images.theconversation.com/files/471251/original/file-20220627-20-ydsy5i.jpg?ixlib=rb-1.1.0&rect=2%2C1%2C782%2C774&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A nanographene molecule imaged by noncontact atomic force microscopy.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Hexabenzocoronene_AFM_2.jpg">Patrik Tschudin/gross3HR/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>What do molecules look like? – Justice B., age 6, Wimberley, Texas</strong></p>
</blockquote>
<hr>
<p>A molecule is a group of atoms bonded together. Molecules make up nearly everything around you – your skin, your chair, even your food. </p>
<p>They vary in size, but are extremely small. You can’t see an individual molecule with your eyes or even a microscope. They are 100,000 times smaller than the <a href="https://hypertextbook.com/facts/1999/BrianLey.shtml">width of a hair</a>.</p>
<p>The smallest molecule is made of two atoms stuck together, while a <a href="https://doi.org/10.1126/science.270.5244.1905-a">large molecule</a> can be a combination of 100,000 atoms or more. A molecule can be a repeat of the same atom, such as the oxygen molecules we breathe, or can be made up of a variety of atoms, such as a sugar molecule made of carbon, oxygen and hydrogen. </p>
<p>But what do molecules look like? It all begins with their building blocks: atoms. </p>
<h2>Opposites attract</h2>
<p>The <a href="https://education.jlab.org/atomtour/">particles of matter that make up an atom</a> are not all the same. They can have a positive charge, a negative charge or no charge. Scientists call them protons, electrons and neutrons. </p>
<figure>
<img src="https://cdn.theconversation.com/static_files/files/2147/A%CC%81tomo_de_Oro.gif?1656372844">
<figcaption> <span class="caption">A gold atom has a dense center made of 79 protons and 118 neutrons, with a more-spread-out cloud of 79 electrons around it. Illustration created by Galarza Creador.</span></figcaption>
</figure>
<p>Neutrons with no charge and protons with a positive charge form the heavy center of the atom. The negatively charged electrons surround this small center.</p>
<p>As atoms approach each other to potentially join and make molecules, the negative electrons in one atom are attracted to the positive protons in the other, and vice versa. Both atoms adjust themselves accordingly.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing a round single atom, top. Below are two atoms stretched into oval shapes, with the positive part of one drawn to the negative part of the other." src="https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=270&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=270&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=270&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=340&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=340&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471509/original/file-20220629-17-tyb14b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=340&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When an atom is alone, the negative electrons surrounding its center are symmetric. As two atoms approach, the negative electrons of one atom move toward the positive center of the other atom.</span>
<span class="attribution"><span class="source">Christine Helms</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>You can compare it to trying to choose a seat in a classroom. There are some rules. For example, you have to stay in the classroom and you cannot sit on top of someone. Following those rules, you might try to sit next to your friends and far from your enemies. Finding the perfect position so everyone in the class is happy is similar to finding the perfect position for the atoms in a molecule. Sometimes, atoms cannot find a happy arrangement and no molecule is formed.</p>
<h2>Seeing the unseeable</h2>
<p>If molecules are too small to see with your eyes or even a powerful microscope, how do scientists see them? The answer is they have developed special tools to do it.</p>
<p>One tool uses X-rays, which you might know about since doctors use them to see bones in the body. <a href="https://theconversation.com/curious-kids-how-do-x-rays-see-inside-you-85895">X-rays are a type of light that human eyes can’t see</a>, <a href="https://www.amnh.org/research/natural-science-collections-conservation/general-conservation/preventive-conservation/light-ultraviolet-and-infrared">like ultraviolet or infrared light</a>. </p>
<p>When scientists <a href="https://www.sciencemuseum.org.uk/objects-and-stories/chemistry/x-ray-crystallography-revealing-our-molecular-world">shoot X-rays at molecules</a>, some bounce off. Scientists can record these rebounding X-rays and use their patterns to figure out what individual molecules look like. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A scattering of black dots on a white background." src="https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471249/original/file-20220627-22-lv4r5v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">X-rays that bounce off the atoms in a protein molecule form the black dots in the above image. The location of these dots tells scientists how the atoms are arranged in the molecule.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Lysozym_diffraction.png">Del45/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In 1912, one of the <a href="https://doi.org/10.1038/491186a">first molecules seen this way was salt</a> (NaCl) – the molecule that makes up the ingredient we all know and love on french fries.</p>
<p>Scientists have invented other methods to see molecules, too. Similar to how the electrons change their behavior as two atoms come close together, the center of the atom can also change its behavior. A technique called <a href="https://www.jeol.co.jp/en/products/nmr/basics.html">nuclear magnetic resonance</a> detects those changes to the center of the atom and uses them as clues to determine what atoms are close by. </p>
<p>An <a href="https://www.parksystems.com/medias/nano-academy/how-afm-works">atomic force microscope</a> works like a flimsy diving board that shakes when you walk and jump on it. But this diving board is extremely small, so small that a negative charge on the end of it will bend it toward the positive center of an atom. Moving this diving board around and watching how it bends can show the location of atoms in a molecule.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/8gCf1sEn0UU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">An animation showing how an atomic force microscope works.</span></figcaption>
</figure>
<p>One more technique scientists have developed to see molecules is called <a href="https://cryoem.slac.stanford.edu/what-is-cryo-em">cyro-electron microscopy</a>. First, scientists freeze molecules to a temperature much colder than snow or ice. Then they shoot electrons at the molecule and collect those that pass through to make an image. <a href="https://theconversation.com/chilled-proteins-and-3-d-images-the-cryo-electron-microscopy-technology-that-just-won-a-nobel-prize-85229">This technique won</a> the <a href="https://www.nobelprize.org/prizes/chemistry/2017/press-release/">Nobel Prize in Chemistry in 2017</a>. </p>
<h2>All shapes and sizes</h2>
<p>So what do molecules look like? They are a grouping of atoms, with the center containing most of the material, while the rest is largely empty space. Each atom has a specific position where it is happy, much like the students in that classroom. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Side by side diagram of a flat molecule and a round molecule." src="https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=396&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=396&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471674/original/file-20220629-21-45b5zt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=396&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diagrams of the atoms making up the molecules benzene, left, and fullerene, right.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Buckminsterfullerene-perspective-3D-balls.png">Jynto (left) Benjah-bmm27 (right)/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>Every molecule is different – some are really different. For example, benzene is flat like a pancake, while fullerene is round like a ball. <a href="http://www.chemspider.com/Chemical-Structure.10338857.html">Penguinone</a> can be drawn to look like a penguin, while other molecules appear to look completely random. But the positions of atoms in a molecule are never random. </p>
<p>While scientists know what a lot of molecules look like, there are some we’re still trying to figure out. Knowing these answers can lead to inventions of new materials and <a href="https://www.mdpi.com/1422-0067/20/11/2783/htm">medicines</a>. </p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/184892/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christine Helms 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>
A physicist explains how atoms arrange themselves into molecules – and how scientists are able to image these tiny bits of matter that make up everything around you.
Christine Helms, Associate Professor of Physics, University of Richmond
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/178465
2022-05-09T19:07:21Z
2022-05-09T19:07:21Z
Electric eels inspired the first battery two centuries ago and now point a way to future battery technologies
<figure><img src="https://images.theconversation.com/files/461098/original/file-20220503-19080-rqhsia.jpg?ixlib=rb-1.1.0&rect=684%2C229%2C2885%2C1741&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Prepare to be stunned by a technology that nature perfected.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/electric-eel-close-up-electrophorus-electricus-royalty-free-image/1298603276">maradek/iStock via Getty Images</a></span></figcaption></figure><p>As the world’s need for large amounts of portable energy grows at an <a href="https://www.rystadenergy.com/newsevents/news/press-releases/powering-up-global-battery-demand-to-surge-by-2030-supply-headaches-on-the-horizon/">ever-increasing pace</a>, many innovators have sought to replace current battery technology with something better.</p>
<p>Italian physicist <a href="https://www.newworldencyclopedia.org/entry/Alessandro_Volta">Alessandro Volta</a> tapped into fundamental electrochemical principles when he invented the first battery in 1800. Essentially, the physical joining of two different materials, usually metals, generates a chemical reaction that results in the flow of electrons from one material to the other. That stream of electrons represents portable energy that can be <a href="https://www.youtube.com/watch?v=PXNKkcB0pI4">harnessed to generate power</a>. </p>
<p>The first materials people employed to make batteries were copper and zinc. Today’s best batteries – those that produce the highest electrical output in the smallest possible size – <a href="https://doi.org/10.1021/acscentsci.7b00288">pair the metal lithium</a> with one of several different metallic compounds. There have been steady improvements over the centuries, but modern batteries rely on the same strategy as that of Volta: pair together materials that can generate an electrochemical reaction and snatch the electrons that are produced.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Drawing of three electric fish species" src="https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461100/original/file-20220503-43085-jyunol.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An 1885 lithograph illustrates several species of electric fish.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/electric-fish-species-catfish-ray-eel-hand-royalty-free-illustration/876169752">ZU_09/DigitalVision Vectors via Getty Images</a></span>
</figcaption>
</figure>
<p>But as I describe in my book “<a href="https://press.princeton.edu/books/hardcover/9780691197838/spark">Spark: The Life of Electricity and the Electricity of Life</a>,” even before humanmade batteries started generating electric current, electric fishes, such as the saltwater torpedo fish (<em><a href="https://www.fishbase.de/summary/2062">Torpedo torpedo</a></em>) of the Mediterranean and especially the various freshwater electric eel species of South America (order <em><a href="https://eol.org/pages/5477">Gymnotiformes</a></em>) were well known to produce electrical outputs of stunning proportions. In fact, electric fishes inspired Volta to conduct the original research that ultimately led to his battery, and today’s battery scientists still look to these electrifying animals for ideas.</p>
<h2>Copying the eel’s electric organ</h2>
<p>Prior to Volta’s battery, the only way for people to generate electricity was to rub various materials together, typically silk on glass, and to capture the resulting static electricity. This was neither an easy nor practical way to generate useful electrical power.</p>
<p>Volta knew electric fishes had an internal organ specifically devoted to generating electricity. He reasoned that if he could mimic <a href="https://www.britannica.com/science/bioelectric-organ">its workings</a>, he might be able to find a novel way to generate electricity.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="line drawing of 19th century man next to scientific apparatus" src="https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=794&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=794&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=794&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=997&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=997&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461101/original/file-20220503-14-gviarx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=997&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Illustration of Alessandro Volta next to his battery stack.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/italian-physicist-alessandro-volta-royalty-free-image/92846303">PHOTOS.com via Getty Images Plus</a></span>
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</figure>
<p>The electric organ of a fish is composed of long stacks of cells that look very much like a roll of coins. So Volta cut out coinlike disks from sheets of various materials and started stacking them, in different sequences, to see if he could find any combination that would produce electricity. These stacking experiments kept yielding negative results until he tried pairing copper disks with zinc ones, while separating the stacked pairs with paper disks wetted with saltwater.</p>
<p>This sequence of copper-zinc-paper fortuitously produced electricity, and the electrical output was proportionate to the height of the stack. Volta thought he had uncovered the secret of how eels generate their electricity and that he had actually produced an artificial version of the electric organ of fish, so he initially called his discovery an “artificial electric organ.” But it was not.</p>
<h2>What really makes eels electrifying</h2>
<p>Scientists now know the <a href="https://socratic.org/questions/what-is-an-electrochemical-reaction">electrochemical reactions</a> between dissimilar materials that Volta discovered have nothing to do with the way an electric eel generates its electricity. Rather, the eel uses an approach similar to the way our nerve cells generate their electrical signals, but on a much grander scale.</p>
<p>Specialized cells within the eel’s electric organ pump ions across a semipermeable membrane barrier to produce an electrical charge difference between the inside versus the outside of the membrane. When microscopic gates in the membrane open, the rapid flow of ions from one side of the membrane to the other generates an electrical current. The eel is able to <a href="http://www.chm.bris.ac.uk/webprojects2001/riis/electriceel3.htm">simultaneously open all of its membrane gates</a> at will to generate a huge jolt of electricity, which it unleashes in a targeted fashion upon its prey.</p>
<p>Electric eels don’t shock their prey to death; they just <a href="https://doi.org/10.1016/j.cub.2017.08.034">electrically stun</a> it before attacking. An eel can generate hundreds of volts of electricity (American household outlets are 110 volts), but the eel’s voltage does not push enough current (amperage), for a long enough time, to kill. Each electric pulse from an eel lasts only a couple thousandths of a second and delivers less than 1 amp. That’s just 5% of household amperage.</p>
<p>This is similar to how electric fences work, delivering very short pulses of high-voltage electricity, but with very low amperage. They thus shock but do not kill bears or other animal intruders that try to get through them. It is also similar to a modern <a href="https://www.britannica.com/topic/TASER">Taser electroshock weapon</a>, which works by quickly delivering an extremely high-voltage pulse (about 50,000 volts) carrying very low amperage (just a few milliamps).</p>
<h2>Modern attempts to mimic the eel</h2>
<p>Like Volta, some modern electrical scientists searching to transform battery technology find their inspiration in electric eels.</p>
<p>A team of scientists from the United States and Switzerland is currently <a href="https://physicsworld.com/a/electric-eel-inspires-new-power-source/">working on a new type of battery inspired by eels</a>. They envision that their soft and flexible battery might someday be useful for internally powering medical implants and soft robots. But the team admits they have a long way to go. “The electric organs in eels are incredibly sophisticated; they’re far better at generating power than we are,” lamented <a href="https://scholar.google.com/citations?user=O6i_eZMAAAAJ&hl=en&oi=ao">Michael Mayer</a>, a team member from the University of Fribourg. So, the eel research continues.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="seated men wearing tuxedos" src="https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461103/original/file-20220503-43468-g6vpmb.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"></a>
<figcaption>
<span class="caption">John Goodenough, M. Stanley Whittingham and Akira Yoshino shared a Nobel Prize for their work on lithium-ion batteries.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/co-laureates-of-the-2019-nobel-prize-in-chemistry-us-news-photo/1187620463">Jonathan Nackstrand/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>In 2019, the Nobel Prize in Chemistry was awarded to the three scientists who <a href="https://www.nobelprize.org/prizes/chemistry/2019/popular-information/">developed the lithium-ion battery</a>. In conferring the award, the Royal Swedish Academy of Sciences asserted that the awardees’ work had “<a href="https://www.nobelprize.org/prizes/chemistry/2019/press-release/">laid the foundation of a wireless, fossil fuel-free society</a>.”</p>
<p>The “wireless” part is definitely true, since lithium-ion batteries now power virtually all handheld wireless devices. We’ll have to wait and see about the “fossil fuel-free society” claim, because today’s lithium-ion batteries are recharged with electricity often generated by burning fossil fuels. No mention was made of the contributions of electric eels.</p>
<p>[<em>Over 150,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-150ksignup">Sign up today</a>.]</p>
<p>Later that same year, though, scientists from the Smithsonian Institution announced their <a href="https://doi.org/10.1038/s41467-019-11690-z">discovery of a new South American species of electric eel</a>; this one is notably the strongest known bioelectricity generator on Earth. Researchers recorded the electrical discharge of a single eel at 860 volts, well above that of the previous record-holding eel species, <em><a href="https://www.fishbase.se/summary/4535">Electrophorus electricus</a></em>, that clocked in at 650 volts, and 200-fold higher that the top voltage of a single lithium-ion battery (4.2 volts).</p>
<p>Just as we humans try to congratulate ourselves on the greatness of our latest portable energy source, the electric eels continue to humble us with theirs.</p><img src="https://counter.theconversation.com/content/178465/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy J. Jorgensen 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>
One species of eel can discharge 860 volts of electricity – that’s 200-fold higher than the top voltage of a single lithium-ion battery.
Timothy J. Jorgensen, Director of the Health Physics and Radiation Protection Graduate Program and Professor of Radiation Medicine, Georgetown University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/130087
2020-05-14T12:04:36Z
2020-05-14T12:04:36Z
A new type of chemical bond: The charge-shift bond
<figure><img src="https://images.theconversation.com/files/318398/original/file-20200303-66099-zi9ikj.jpg?ixlib=rb-1.1.0&rect=28%2C18%2C3054%2C1960&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A universe of chemical equations.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/science-old-chemistry-laboratory-seamless-pattern-276554942">Nikolayenko Yekaterina/Shutterstock.com</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/287050/original/file-20190806-84240-i26yzq.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/287050/original/file-20190806-84240-i26yzq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=171&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287050/original/file-20190806-84240-i26yzq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=171&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287050/original/file-20190806-84240-i26yzq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=171&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287050/original/file-20190806-84240-i26yzq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=215&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287050/original/file-20190806-84240-i26yzq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=215&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287050/original/file-20190806-84240-i26yzq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=215&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>The Abstract features interesting research and the people behind it.</em></p>
<hr>
<p><a href="https://www.researchgate.net/profile/John_Galbraith">John Morrison Galbraith</a> is an associate professor of chemistry at Marist College who studies chemical bonding, which is the process that holds atoms together to make molecules. </p>
<p><strong>What have you discovered?</strong></p>
<p>Did you take a chemistry course in high school? Did you think it was a boring static field filled with established facts that were determined a long time ago? I’ve done research that shows that the most fundamental of these established “facts,” the nature of the chemical bond, is now being questioned.</p>
<p>You have likely heard of covalent bonds, where electrons are shared between atoms, and ionic bonds, where electrons are completely transferred from one atom to another. But you probably don’t know about a third type of bond, discovered in the early 1990s by <a href="http://yfaat.ch.huji.ac.il/sason/sason.php">Sason Shaik</a> and <a href="http://pagesperso.lcp.u-psud.fr/hiberty/">Philippe Hiberty</a>: <a href="https://doi.org/10.1002/anie.201910085">the charge-shift bond</a>. I began working with them soon after. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/334505/original/file-20200512-82388-pcsd25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/334505/original/file-20200512-82388-pcsd25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=534&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334505/original/file-20200512-82388-pcsd25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=534&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334505/original/file-20200512-82388-pcsd25.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=534&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334505/original/file-20200512-82388-pcsd25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=672&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334505/original/file-20200512-82388-pcsd25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=672&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334505/original/file-20200512-82388-pcsd25.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=672&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The three types of chemical bonds. Red indicates electron-rich areas and blue indicates electron-deficient areas. (Top) the covalent bond in the hydrogen molecule showing electron build up in the bonding region between two indivual hydrogen atoms.</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/334506/original/file-20200512-82388-1u9m9z6.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/334506/original/file-20200512-82388-1u9m9z6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=352&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334506/original/file-20200512-82388-1u9m9z6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=352&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334506/original/file-20200512-82388-1u9m9z6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=352&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334506/original/file-20200512-82388-1u9m9z6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=442&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334506/original/file-20200512-82388-1u9m9z6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=442&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334506/original/file-20200512-82388-1u9m9z6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=442&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The ionic bond in sodium chloride (table salt) showing electron transfer to the chlorine side (right).</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/334507/original/file-20200512-82370-1hqwkkd.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/334507/original/file-20200512-82370-1hqwkkd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334507/original/file-20200512-82370-1hqwkkd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334507/original/file-20200512-82370-1hqwkkd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334507/original/file-20200512-82370-1hqwkkd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334507/original/file-20200512-82370-1hqwkkd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334507/original/file-20200512-82370-1hqwkkd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The charge-shift bond of the fluorine molecule showing electron depletion in the bonding region.</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p><strong>What makes a charge-shift bond different?</strong></p>
<p>In charge-shift bonds, electrons are both shared and transferred at the same time. </p>
<p>That might sound a little crazy, but think of it like this: You know those movable walkways at airports? Suppose that for over 100 years, people thought that the only way to get from one point to another was to either stand on the moving walkway or walk alongside it. </p>
<p>Now suppose that someone realized that there is a third way to move: You can stand on the walkway and walk at the same time. The speed at which you move through the airport is not due to standing or walking, but a combination of both. </p>
<p><a href="https://doi.org/10.1038/nchem.327">Along with Shaik, Hiberty</a> and a handful of others around the world, <a href="https://doi.org/10.1021/jp049632o">I</a> <a href="https://doi.org/10.1021/acs.jpca.7b02988">have helped</a> show that charge-shift bonding is a broad phenomenon that happens between a variety of elements from across the periodic table. </p>
<p><strong>What inspired this discovery?</strong></p>
<p>Shaik and Hiberty were calculating the energy required to break a series of bonds using a method called valence bond theory. Chemistry is all about pattern recognition, and all of the bonds they studied fit a well-established pattern, except the bond between two fluorine atoms. Traditionally thought of as a purely covalent bond, this molecule didn’t behave like any other covalent bond. By trying to understand why, Shaik and Hiberty uncovered something completely unique. </p>
<p><strong>Why is it important?</strong></p>
<p>This is the first major change in the way chemists think about bonding in more than 100 years. Chemical bonding is at the heart of chemistry, so changing the way chemists think about bonding will change the entire field. </p>
<p><strong>How are charge-shift bonds applied in the real world?</strong></p>
<p>Synthetic <a href="https://www.ted.com/talks/cathy_mulzer_the_incredible_chemistry_powering_your_smartphone">materials</a> such as <a href="https://cen.acs.org/materials/2-d-materials/Method-irons-2-D-materials/96/i49">computer chips</a>, <a href="https://cen.acs.org/articles/88/i16/Plastic-Logic-Links-Germanys-Merck.html">plastics</a>, <a href="http://cenblog.org/just-another-electron-pusher/2011/09/the-science-of-beauty-cosmetic-chemistry/">cosmetics</a>, <a href="https://cen.acs.org/articles/93/web/2015/03/Motion-Powered-Fabric-Charge-Small.html">textiles</a> and <a href="https://cen.acs.org/articles/93/i43/Revolution-Medicines.html">medicines</a> come from making and breaking chemical bonds. </p>
<p>Therefore, insight into chemical bonding can inspire new materials with properties we have yet to imagine. We are already seeing chemists exploit the properties of charge-shift bonds to speed up chemical reactions and to understand the properties of industrial solvents.</p>
<p><strong>What is the coolest element of your new research?</strong></p>
<p>Chemistry is alive and constantly changing – that’s what first attracted me to the field. Charge-shift bonding challenges something so fundamental to the field that it is largely taken for granted. </p>
<p>The drama of sweeping theory change is in full effect here: The concept was introduced many years ago but not rapidly accepted; over time, diligent work by a handful of believers provided more support for the idea; and now it is gaining <a href="https://www.chemistryworld.com/features/what-is-a-bond/6983.article">widespread acceptance</a> due to verification through alternative <a href="https://doi.org/10.1021/ja053130m">experimental</a> and <a href="https://doi.org/10.1021/acs.jctc.6b00571">theoretical</a> means. </p>
<p>I also find it fascinating that most chemical processes can now be reliably modeled on a computer. I always liked chemistry for the knowledge it provided about how things work on the atomic scale. However, I never felt comfortable playing with beakers and hazardous chemicals. While chemistry is still a predominantly experimental science, today computers can direct those experiments while also providing a place for an experimentally challenged chemist such as myself.</p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p><img src="https://counter.theconversation.com/content/130087/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cottrell College Science Award for $35,718: Marist College, May 2006 - May 2008.
Merk AAAS Undergraduate Science Research Program Award: Marist College, Summer 2004 - Summer 2005.</span></em></p>
The laws and principles of chemistry seem pretty set in stone. But as a chemist explains, the field is always evolving, including such fundamental principles as what is a chemical bond.
John Morrison Galbraith, Associate Professor of Chemistry, Marist College
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/118234
2019-06-05T10:41:12Z
2019-06-05T10:41:12Z
2D spintronics has already transformed computing – now we’re making it work in three dimensions
<figure><img src="https://images.theconversation.com/files/277878/original/file-20190604-69075-1s3e7n3.jpg?ixlib=rb-1.1.0&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/abstract-background-163743035?src=avU0DY-XMpU4W1RuKZPhfA-1-86">Deniseus</a></span></figcaption></figure><p><a href="https://theconversation.com/shift-from-electronics-to-spintronics-opens-up-possibilities-of-faster-data-45864">Spintronics</a> might not be the sort of word that comes up in everyday discussions, but it has been revolutionising computer technology for years. It’s the branch of physics that involves manipulating the spin of a flow of electrons, which first reached consumers in the late 1990s in the form of magnetic computer hard drives with several hundreds of times the storage capacity of their predecessors. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1026&fit=crop&dpr=1 600w, https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1026&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1026&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1289&fit=crop&dpr=1 754w, https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1289&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/277923/original/file-20190604-69059-1rnkyks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1289&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Remember me?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/vector-mp3-player-53699233?src=qYJ2tOgj7jex4cr1-kFz9w-1-23">leviana</a></span>
</figcaption>
</figure>
<p>These and other electronic devices have <a href="https://www.youtube.com/watch?v=3PMbN0PVyy0">since been refined</a> to make computers many times more powerful again, not to mention much cooler and more energy efficient – enabling everything from MP3 players to the smartphones of today. <a href="https://newsroom.intel.com/news/intel-starts-testing-smallest-spin-qubit-chip-quantum-computing/#gs.g5k0jo">Intel</a> and <a href="https://ai.googleblog.com/2018/03/a-preview-of-bristlecone-googles-new.html">Google</a> began unveiling quantum processors last year, and <a href="https://news.samsung.com/global/samsung-electronics-starts-commercial-shipment-of-emram-product-based-on-28nm-fd-soi-process">Samsung</a> and <a href="https://www.everspin.com/news/everspin-ships-world%E2%80%99s-first-pre-production-28-nm-1-gb-stt-mram-customer-samples">Everspin</a> launched MRAM (magnetic random access memory) chips a few months ago. This new technology is expected to substantially improve computing performance – by <a href="https://www.spintronics-info.com/nec-and-tohoku-university-developed-spintronics-text-search-chip-cuts-power-reduction-99">one estimate</a>, for example, the potential reduction in power requirements could be over 99%. </p>
<p>Even so, all these advances have been labouring under a major limitation: the spin manipulation is confined to a single ultra-thin layer of magnetic material. Tens of these layers are typically stacked in a “sandwiched” structure, which interact through complex interfaces and interconnects, but their functionality is fundamentally 2D in nature. </p>
<p>Industry leaders like Stuart Parkin, who created IBM’s original spintronics-driven computer hard drive, the <a href="https://www.ibm.com/ibm/history/ibm100/us/en/icons/spintronics/">Deskstar 16GP Titan</a>, have <a href="https://youtu.be/kB0ixO5lrzQ">been saying</a> for years that one of the biggest challenges in magnetic computing is to shift to a much more flexible and capable 3D version.</p>
<p>This would see information transmitted, stored and processed across any point of the three-dimensional stack of magnetic layers. Recent pioneering <a href="https://www.spintronics-info.com/worlds-first-3d-spintronics-chip-developed-cambridge">advances</a> are starting to bring this paradigm shift <a href="https://www.agenciasinc.es/en/News/Three-Dimensional-Nanomagnets-for-the-computer-of-tomorrow">closer</a>, but we still face great challenges to reach the same degree of control as we have in two dimensions. </p>
<p>In a <a href="https://www.nature.com/articles/s41563-019-0386-4">new paper</a> led by the universities of Glasgow and Cambridge, in collaboration with researchers at the University of Hamburg, the Technical University of Eindhoven and the Aalto University School of Science, we have taken a significant step towards achieving that goal.</p>
<h2>Spins and charges</h2>
<p>Traditional electronics is based on the fact that electrons have electrical charges. In a basic computer, chips and other units transmit information by sending and receiving tiny electrical pulses. They register a “one” for a pulse and a “zero” for no pulse, and by counting these over millions of repetitions, it becomes the basis of a language of instructions. </p>
<p>Traditional magnetic hard drives rely on properties associated to electrical charges too, but they work on a different principle, with very tiny regions of a flat magnetic disk recording zeroes and ones via its two possible magnetic orientations. Magnetic drives have the great benefit that data is still there even when the power is switched off, though the information is recorded and retrieved much more slowly than using the transistors that we find in computer circuits. </p>
<p>Spintronics is different: it exploits both the charge and the intrinsic magnetism of electrons - otherwise known as its spin. The difference between spin and charge is sometimes likened to the way that the Earth orbits the sun but also spins on its axis at the same time. But whereas electrons are always negatively charged, they can spin “up” or “down”.</p>
<p>It was <a href="https://www.nobelprize.org/prizes/physics/2007/summary/">discovered</a> in the late 1980s that if an electrical current was conducted through a device formed by a non-magnetic sheet sandwiched between two magnetic sheets, the resistance of this device to the electron flow would change dramatically depending on the orientation of the magnets within the two magnetic sheets. </p>
<p>This effect was readily exploited in hard drives, with these spintronic systems acting as very sensitive sensors that could read many more zeroes and ones of magnetic information within the same area than previous hard drives – thus transforming storage capacity. Known as giant magnetoresistance, this later yielded the <a href="https://www.nobelprize.org/prizes/physics/2007/summary/">Nobel Prize in Physics</a> for Albert Fert and Peter Grunberg, the two scientists who discovered it simultaneously. </p>
<h2>Chiral spintronics</h2>
<p>Since the birth of spintronics, there have been many important advances, including some recent exciting ones in an area called chiral spintronics. Whereas we usually think of two magnets as having a “north” and “south” that rotate towards or away from one another along a 180º line – watch the compass towards the end of <a href="https://youtu.be/Mp0Bu75MSj8">this video</a> for example – under particular conditions, tiny magnets at the atomic level also present chiral spin interactions. This means that neighbouring magnets have a preference to orient at angles of 90º. </p>
<p>The existence of these interactions is a key ingredient to create and manipulate pseudo-particles called magnetic skyrmions, which have topological properties that <a href="https://eandt.theiet.org/content/articles/2019/05/could-skyrmions-change-the-future-of-computing/">enable them</a> to perform computing applications more effectively, with huge potential to further improve data storage. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/277933/original/file-20190604-69075-940e9s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An attractive notion.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/magnet-plant-lines-triangles-point-connecting-753575932?src=H1nOZS9ebp625GHgnLRDlQ-1-22">piick</a></span>
</figcaption>
</figure>
<p>Until now, however, chiral spin interactions had only been observed and exploited in 2D spintronics. In our new paper, we show for the first time that this interaction can be also created between magnets located at two neighbouring magnetic layers separated by an ultra-thin non-magnetic metallic layer. </p>
<p>For this, we created a device with a total of eight layers using a technique called <a href="https://www.youtube.com/watch?v=L6ZIkmIVm6c">sputtering</a> to deposit nanoscale thin films. We had to carefully tune the interfaces of the layers to balance other magnetic interactions, and we studied the behaviour of the system under magnetic fields at room temperature employing lasers. The way the device behaved was confirmed by complementary magnetic simulations performed by our collaborator at the University of Hamburg. </p>
<p>This discovery opens new exciting routes to exploit further 3D spintronic effects, with chiral spin interactions playing a pivotal role to create more compact and efficient ways to store and move magnetic data along the whole 3D space. Future work will focus on finding ways to increase the strength of this interaction and expand the range of devices where the effect is present. We expect our work will attract great interest within the spintronic community and stimulate industry to continue working on magnetic computing devices based on these radically new concepts.</p>
<p>The first impact of spintronics in the computing market was extremely fast – it took just eight years from the discovery of giant magnetoresistance to the launch of IBM’s Deskstar 16GP Titan in 1997. The leap to 3D still needs to overcome multiple obstacles, from precisely fabricating the necessary devices to exploiting magnetic interactions in unconventional computing architectures. Our recent discovery brings us a step closer to achieving this very challenging but exciting objective.</p><img src="https://counter.theconversation.com/content/118234/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amalio Fernandez-Pacheco receives funding from the UK Engineering and Physical Science Research Council, the Winton Programme for the Physics of Sustainability, and the Royal Society. He is also affiliated with the University of Cambridge.</span></em></p>
Manipulating electron spin has heralded everything from iPods to the latest laptops. Stand by for the next paradigm shift.
Amalio Fernandez-Pacheco, EPSRC Early Career Fellow, Physics and Astronomy, University of Glasgow
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/109145
2019-01-09T12:48:29Z
2019-01-09T12:48:29Z
Curious Kids: is everything really made of molecules?
<figure><img src="https://images.theconversation.com/files/252701/original/file-20190107-32154-zq4nrg.jpg?ixlib=rb-1.1.0&rect=121%2C87%2C4369%2C3009&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is this it?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/little-girl-elementary-school-constructs-model-1089743798">Shutterstock.</a></span></figcaption></figure><p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series for children of all ages, where The Conversation asks experts to answer questions from kids. All questions are welcome: find out how to enter at the bottom of this article.</em> </p>
<hr>
<blockquote>
<p><strong>People say that everything is made of molecules. Are feelings made of molecules? Is sound made of molecules? – Claire, age six, Bristol, UK</strong></p>
</blockquote>
<p>Thanks for the question, Claire. First things first: when people say “everything”, often they actually mean the stuff that scientists call “matter”. Matter is stuff you can touch. But feelings are not matter, and neither is sound. </p>
<p>Things that are matter include stars, air, water, tables, chairs, trees, your body, your brain, and pretty much everything that you see around you. </p>
<p>All of these things are made up of molecules – but molecules aren’t the smallest pieces of matter, because every molecule is made up of <a href="http://particleadventure.org/">even smaller pieces</a> called atoms. </p>
<p>And atoms themselves are made up of even tinier pieces. One of the tiniest types of pieces that makes up matter is called the electron. </p>
<h2>Electrons and emotions</h2>
<p>Things that are not matter include feelings, thoughts and light. Light allows us to see all of the things around us, but it’s different from matter. The main difference is that it doesn’t weigh anything. Even air has a weight, but light doesn’t.</p>
<p>Feelings and thoughts also don’t have a weight, and are not matter. But they’re not light, either. Feelings and thoughts live inside our brains. </p>
<p>The way that the matter in our brains acts <a href="https://science.howstuffworks.com/life/inside-the-mind/human-brain/5-ways-your-brain-influences-your-emotions.htm">affects our feelings and thoughts</a>, and our feelings and thoughts can affect the way the matter in our brain acts. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/252502/original/file-20190104-32121-3n3ufm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/252502/original/file-20190104-32121-3n3ufm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=386&fit=crop&dpr=1 600w, https://images.theconversation.com/files/252502/original/file-20190104-32121-3n3ufm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=386&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/252502/original/file-20190104-32121-3n3ufm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=386&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/252502/original/file-20190104-32121-3n3ufm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=485&fit=crop&dpr=1 754w, https://images.theconversation.com/files/252502/original/file-20190104-32121-3n3ufm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=485&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/252502/original/file-20190104-32121-3n3ufm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=485&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Feelings aren’t matter, but your brain is.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/asian-child-girl-green-concrete-wall-646493059?src=CjrH8uCLN5iO1fdkA9cvJQ-1-7">Shutterstock.</a></span>
</figcaption>
</figure>
<p>Scientists don’t yet know exactly how thoughts are made, but they do know that it has something to do with the way those tiniest pieces of matter – electrons – move around to create <a href="https://learn.genetics.utah.edu/content/neuroscience/neurons/">an electrical signal</a>, like the signals that are sent from a light switch to turn a light on. </p>
<p>For example, scientists have found out that your brain <a href="https://www.livescience.com/32798-how-are-memories-stored-in-the-brain.html">holds on to memories</a> by keeping electrons in certain places. </p>
<p>There are different kinds of feelings. There are feelings that your body tells you, like when you burn your finger on a candle or when you feel hungry. And there are feelings that we call emotions, like when you’re sad or excited. </p>
<p>Both kinds of feelings are made in your brain and both kinds have to do with those electrons again, with how they move and where they sit in your brain.</p>
<h2>Sensing sound</h2>
<p>Sound is a different thing again. Sound is made of waves, but not really like waves on the ocean. <a href="https://www.physicsclassroom.com/mmedia/waves/lw.cfm">Soundwaves are created</a> when the molecules around us move in a certain way. </p>
<p>Imagine you’re playing some loud music through a speaker. If you touch the front of a speaker while the music’s playing, you should be able to feel it jiggle.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/mZURZtkf9WM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The jiggle of the speaker causes the molecules in the air around it to jiggle and bump into each other. </p>
<p>That little jiggle causes the other molecules nearby to jiggle, and the jiggles pass from one group of air molecules to another, until they finally reach the air molecules next to your ear drum. </p>
<p>Your ear drum is very sensitive, and can tell that the air molecules are jiggling, so it sends a special message to your brain. Your brain gets the message and says, “that’s music!” – and that’s <a href="https://www.nidcd.nih.gov/health/how-do-we-hear">how you hear</a> the song. </p>
<p>So, neither feelings nor sound are made of molecules in the same way that matter is. But they both have a lot to do with the way molecules – and their smaller parts, atoms and electrons – move around. </p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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</figure>
<p><em>Please tell us your name, age and which town or city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question, but we will do our best.</em></p>
<hr>
<p><em>More <a href="https://theconversation.com/topics/curious-kids-36782?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Curious Kids</a> articles, written by academic experts:</em></p>
<ul>
<li><p><em><a href="https://theconversation.com/curious-kids-is-it-true-dogs-dont-like-to-travel-108670?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Is it true dogs don’t like to travel? – Ankush, India</a></em></p></li>
<li><p><em><a href="https://theconversation.com/curious-kids-how-do-eyes-grow-108489?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">How do eyes grow? – Annette, age seven, Stratford-upon-Avon, UK</a></em></p></li>
<li><p><em><a href="https://theconversation.com/curious-kids-who-were-the-spartans-108606?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Who were the Spartans? – Trystan, a young reader from Australia</a></em></p></li>
</ul><img src="https://counter.theconversation.com/content/109145/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laura Kormos 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>
Everything you can touch is made of molecules – but feelings, sound and light are something different.
Laura Kormos, Senior Lecturer in Physics, Lancaster University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/99156
2018-07-02T17:47:38Z
2018-07-02T17:47:38Z
Graphene and the atomic crystals that could see next big breakthrough in tech
<figure><img src="https://images.theconversation.com/files/225738/original/file-20180702-116135-1nfm3nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ready layer one. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/illustration-graphene-molecule-luminous-atoms-crystal-1026845797?src=UWnzYyZVG66GP5lzo-hoig-1-10">tschub</a></span></figcaption></figure><blockquote>
<p>What could we do with layered structures with just the right layers? What would the properties of materials be if we could really arrange the atoms the way we want them?</p>
</blockquote>
<p>The curious American physicist <a href="https://fs.blog/richard-feynman/">Richard Feynman</a> asked these questions in his landmark 1959 lecture, <a href="http://www.phy.pku.edu.cn/%7Eqhcao/resources/class/QM/Feynman%27s-Talk.pdf">There’s Plenty of Room at the Bottom</a>. It bustled with profound ideas about “manipulating and controlling things on the atomic scale”, using quantum mechanics. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=719&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=719&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=719&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=904&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=904&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225736/original/file-20180702-116139-52rp50.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=904&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Atomic adventurer: Richard Feynman.</span>
<span class="attribution"><a class="source" href="https://it.wikipedia.org/wiki/File:Richard-feynman.jpg#/media/File:Richard-feynman.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<p>Far-fetched at the time, now manipulating layers of atoms is a major research area. To realise Feynman’s vision, researchers at IBM and Bell Labs in the US had to devise a new approach to constructing materials layer by layer: <a href="https://warwick.ac.uk/fac/sci/physics/current/postgraduate/regs/mpagswarwick/ex5/growth/pvd/">molecular beam epitaxy</a> or MBE. </p>
<p>This can be likened to spray painting with atoms. You start by vaporising ultra-pure source materials like gallium, aluminium or indium, and combine them with the likes of arsenic or phosphorus. The vaporised atoms fly through a vacuum chamber towards a base layer made of similar materials. The atoms stick to it and slowly build up a crystal one atomic layer at a time. The ultra-high vacuum ensures impurities are minimal. </p>
<h2>Atomic architects</h2>
<p>While the process is relatively slow – typically only a few atomic layers per minute – the precision is remarkable. It allows technicians to stack different <a href="http://ethw.org/Semiconductors">semiconductor</a> materials on top of each other to create crystals known as <a href="https://theconversation.com/beyond-graphene-scientists-are-creating-an-atomic-lego-set-of-2d-wonder-materials-81709">heterostructures</a>, which can have extremely useful properties. By alternately stacking layers of aluminium arsenide and gallium arsenide, for example, you could produce a material that is extremely good at storing electricity. </p>
<p>Once this technique had been perfected in 1990s and 2000s, scientists were able to control the number of electrons and their energies in a particular crystal. And since light then interacts with these electrons, having more control over electron behaviour means you also gain more control of how they are stimulated by light. </p>
<p>Heterostructures have led to many new discoveries, particularly regarding the quantum behaviour of particles such as electrons within them. Nobel Prizes in Physics have been awarded five separate times (<a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1973/index.html">1973</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1985/index.html">1985</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1998/">1998</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/2000/">2000</a>, and <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/2014/">2014</a>), and the resulting materials have revolutionised civilisation. </p>
<p>Semiconductor heterostructures enable solar cells, LEDs, lasers and ultra-fast transistors. Even the internet would otherwise be impossible: the lasers which send the light pulses that encode the bits of information online are made from heterostructures, as are the photodetectors that measure these light pulses and decode the information.</p>
<p>There are restrictions, however. The atomic size, spacing and arrangement of these heterostructures cannot be too dissimilar between layers without defects arising. This limits the possible material combinations and the potential to freely engineer the electronic and optical properties. </p>
<p>Also, crystals naturally consist of atoms which form bonds in all three directions. This means there are always unsatisfied atoms with “dangling” bonds at the edges. Foreign impurities seek these bonds and create defects that can destroy other properties. This becomes especially important with smaller crystals, preventing them being integrated to their full extent into modern transistors, lasers and so forth. </p>
<h2>Enter 2D crystals</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=712&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=712&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=712&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=895&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=895&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225730/original/file-20180702-116123-e1wmih.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=895&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Graphene.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-illustration-graphene-material-molecular-grid-761990035?src=xMi-LIYHLvwuYH0jv2AyFQ-1-1">Olive Tree</a></span>
</figcaption>
</figure>
<p>The ultimate in ultra-thin sheets of materials is a single layer of atoms. Fortunately, nature devised such “two-dimensional crystals”. The most famous is <a href="https://theconversation.com/uk/topics/graphene-992">graphene</a>, which is just carbon atoms arranged in a hexagonal pattern. </p>
<p>Graphene is stronger than steel and conducts electricity better than copper. It has many unique and sometimes exotic electronic, optical and mechanical properties – as recognised by the <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/2010/press.html">Nobel Prize in Physics</a> for its discovery in 2010. </p>
<p>In a perfect graphene crystal, all the atoms are completely bonded to one another and there are no dangling bonds. It is famously possible to produce graphene by peeling apart layers of graphite using scotch tape: graphite is actually many layers of graphene all held together by <a href="https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/Atomic_and_Molecular_Properties/Intermolecular_Forces/Van_der_Waals_Forces">Van der Waals forces</a>, which are far weaker than the bonds in each constituent sheet of graphene. </p>
<p>Besides graphene, there are many other 2D crystals, each with unique properties. Several occur naturally as gems in the ground, such as molybdnimum disulphide, an important industrial lubricant. Others can be made by molecular beam epitaxy, such as the insulator boron nitride, and crystals in the same family of <a href="https://www.sciencedirect.com/science/article/pii/S1369702116302917">transition metal dichalcogenides</a> as molybdnimum disulphide. </p>
<p>Like graphene is to graphite, scientists “peel off” (or exfoliate) single 2D sheets from larger quantities of these compounds. The inherent thinness of these sheets means they can behave quite differently from the heterostructures described earlier. Different atomically thin materials can be insulating, semiconducting, metallic, magnetic or even superconducting.</p>
<p>Scientists are also able to pick, place and combine these materials at will to form new heterostructures, known as Van der Waals heterostructures, with different properties to the 2D sheets. Crucially, these don’t have the same limitations as their cousins made by molecular beam epitaxy. They can comprise layers of very different atomic crystals, enabling unprecedented and unlimited possibilities for combining different materials.</p>
<p>For example, you can combine magnetic layers with semiconductors and insulators without attracting contaminants like moisture or oxides between layers – impossible with epitaxial heterostructures. This can be used to create devices that control magnetism using electricity, which is the basis for magnetic memory in hard drives. </p>
<p>You can also stack together two identical atomic layers with one turned at an angle. This creates a lattice called a moiré pattern, which provides a new degree of freedom to engineer the electronic and optical properties. The images we are using to demonstrate this at the <a href="https://royalsociety.org/science-events-and-lectures/2018/summer-science-exhibition/exhibits/atomic-architects/">current Royal Society Summer Exhibition</a> in London give a flavour of how this works:</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=288&fit=crop&dpr=1 600w, https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=288&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=288&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=362&fit=crop&dpr=1 754w, https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=362&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/225919/original/file-20180703-116126-1b5pgj2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=362&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Moire power to your elbow.</span>
<span class="attribution"><span class="source">University of Heriot-Watt</span></span>
</figcaption>
</figure>
<p>While Van der Waals heterostructures are still in their infancy, impressive new physics and capabilities are already emerging. These include smaller, lighter, more flexible and more efficient versions of solar cells, LEDs, transistors and magnetic memory. </p>
<p>In future, we can expect surprises not previously dreamed of. An early example is the <a href="https://www.nature.com/articles/nature26160">recent discovery</a> that when you twist two layers of graphene at a “magic angle” relative to each other, the electrons become superconducting. This breakthrough, not clearly understood yet, could unlock 30-year-old mysteries of how electrons can navigate superconductors without losing any energy. It might allow us to use superconductors at room temperature, with potential benefits for everything from medical imaging and quantum computers to transmitting electricity long distances. </p>
<p>Predicting technological outcomes is not easy, however. As Herbert Kroemer, who shared the Nobel Prize in 2000 for developing semiconductor heterostructures used in high-speed and opto-electronics, <a href="https://www.ece.ucsb.edu/Faculty/Kroemer/pubs/11_03Speculations.pdf">often said</a>: </p>
<blockquote>
<p>The principal applications of any sufficiently new and innovative technology always have been and will continue to be applications created by that technology.</p>
</blockquote><img src="https://counter.theconversation.com/content/99156/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brian Gerardot 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>
Layering substances like graphene in new ways could help us to build quantum computers or transmit electricity over long distances.
Brian Gerardot, Chair in Emerging Technologies, Heriot-Watt University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/94700
2018-05-23T10:39:19Z
2018-05-23T10:39:19Z
The Standard Model of particle physics: The absolutely amazing theory of almost everything
<figure><img src="https://images.theconversation.com/files/219824/original/file-20180521-14978-36nv6i.jpg?ixlib=rb-1.1.0&rect=174%2C0%2C977%2C649&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">How does our world work on a subatomic level?</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Varsha_ys.jpg">Varsha Y S</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The Standard Model. What a dull name for the most accurate scientific theory known to human beings.</p>
<p>More than a quarter of the Nobel Prizes in physics of the last century are direct inputs to or direct results of the Standard Model. Yet its name suggests that if you can afford a few extra dollars a month you should buy the upgrade. <a href="https://scholar.google.com/citations?user=eQiX0m4AAAAJ&hl=en&oi=ao">As a theoretical physicist</a>, I’d prefer The Absolutely Amazing Theory of Almost Everything. That’s what the Standard Model really is.</p>
<p>Many recall the excitement among scientists and media over the 2012 <a href="https://home.cern/topics/higgs-boson">discovery of the Higgs boson</a>. But that much-ballyhooed event didn’t come out of the blue – it capped a five-decade undefeated streak for the Standard Model. Every fundamental force but gravity is included in it. Every attempt to overturn it to demonstrate in the laboratory that it must be substantially reworked – and there have been many over the past 50 years – has failed. </p>
<p>In short, the <a href="https://home.cern/about/physics/standard-model">Standard Model</a> answers this question: What is everything made of, and how does it hold together?</p>
<h2>The smallest building blocks</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">But these elements can be broken down further.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Periodic_table_vectorial.png">Rubén Vera Koster</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>You know, of course, that the world around us is made of molecules, and molecules are made of atoms. Chemist <a href="https://www.famousscientists.org/dmitri-mendeleev/">Dmitri Mendeleev</a> figured out in the 1860s how to organize all atoms – that is, the elements – into the periodic table that you probably studied in middle school. But there are 118 different chemical elements. There’s antimony, arsenic, aluminum, selenium … and 114 more.</p>
<p>Physicists like things simple. We want to boil things down to their essence, a few basic building blocks. Over a hundred chemical elements is not simple. The ancients believed that everything is made of just five elements – <a href="https://en.wikipedia.org/wiki/Classical_element">earth, water, fire, air and aether</a>. Five is much simpler than 118. It’s also wrong. </p>
<p>By 1932, scientists knew that all those atoms are made of just three particles – neutrons, protons and electrons. The neutrons and protons are bound together tightly into the nucleus. The electrons, thousands of times lighter, whirl around the nucleus at speeds approaching that of light. Physicists <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1918/planck-bio.html">Planck</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1922/bohr-bio.html">Bohr</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1933/schrodinger-bio.html">Schroedinger</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1932/heisenberg-bio.html">Heisenberg</a> and friends had invented a new science – <a href="https://en.wikipedia.org/wiki/Quantum_mechanics">quantum mechanics</a> – to explain this motion.</p>
<p>That would have been a satisfying place to stop. Just three particles. Three is even simpler than five. But held together how? The negatively charged electrons and positively charged protons are bound together by <a href="https://en.wikipedia.org/wiki/Electromagnetism">electromagnetism</a>. But the protons are all huddled together in the nucleus and their positive charges should be pushing them powerfully apart. The neutral neutrons can’t help. </p>
<p>What binds these protons and neutrons together? “Divine intervention” a man on a Toronto street corner told me; he had a pamphlet, I could read all about it. But this scenario seemed like a lot of trouble even for a divine being – keeping tabs on every single one of the universe’s 10⁸⁰ protons and neutrons and bending them to its will. </p>
<h2>Expanding the zoo of particles</h2>
<p>Meanwhile, nature cruelly declined to keep its zoo of particles to just three. Really four, because we should count the <a href="https://en.wikipedia.org/wiki/Photon">photon</a>, the particle of light that <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1921/einstein-bio.html">Einstein</a> described. Four grew to five when <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1936/anderson-bio.html">Anderson</a> measured electrons with positive charge – positrons – striking the Earth from outer space. At least <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1933/dirac-bio.html">Dirac</a> had predicted these first anti-matter particles. Five became six when the pion, which <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1949/yukawa-bio.html">Yukawa</a> predicted would hold the nucleus together, was found. </p>
<p>Then came the muon – 200 times heavier than the electron, but otherwise a twin. “Who ordered that?” <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1944/rabi-bio.html">I.I. Rabi</a> quipped. That sums it up. Number seven. Not only not simple, redundant.</p>
<p>By the 1960s there were hundreds of “fundamental” particles. In place of the well-organized periodic table, there were just long lists of baryons (heavy particles like protons and neutrons), mesons (like <a href="https://en.wikipedia.org/wiki/Hideki_Yukawa">Yukawa</a>’s pions) and leptons (light particles like the electron, and the elusive neutrinos) – with no organization and no guiding principles.</p>
<p>Into this breach sidled the Standard Model. It was not an overnight flash of brilliance. No Archimedes leapt out of a bathtub shouting “eureka.” Instead, there was a series of crucial insights by a few key individuals in the mid-1960s that transformed this quagmire into a simple theory, and then five decades of experimental verification and theoretical elaboration. </p>
<p><a href="https://home.cern/about/updates/2014/01/fifty-years-quarks">Quarks</a>. They come in six varieties we call flavors. Like ice cream, except not as tasty. Instead of vanilla, chocolate and so on, we have up, down, strange, charm, bottom and top. In 1964, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1969/gell-mann-bio.html">Gell-Mann</a> and <a href="https://www.macfound.org/fellows/113/">Zweig</a> taught us the recipes: Mix and match any three quarks to get a baryon. Protons are two ups and a down quark bound together; neutrons are two downs and an up. Choose one quark and one antiquark to get a meson. A pion is an up or a down quark bound to an anti-up or an anti-down. All the material of our daily lives is made of just up and down quarks and anti-quarks and electrons.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=536&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=536&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=536&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=673&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=673&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=673&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 Standard Model of elementary particles provides an ingredients list for everything around us.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Standard_Model_From_Fermi_Lab.jpg">Fermi National Accelerator Laboratory</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Simple. Well, simple-ish, because keeping those quarks bound is a feat. They are tied to one another so tightly that you never ever find a quark or anti-quark on its own. The theory of that binding, and the particles called gluons (chuckle) that are responsible, is called <a href="https://en.wikipedia.org/wiki/Quantum_chromodynamics">quantum chromodynamics</a>. It’s a vital piece of the Standard Model, but mathematically difficult, even posing an unsolved problem of basic mathematics. We physicists do our best to calculate with it, but we’re still learning how.</p>
<p>The other aspect of the Standard Model is “<a href="https://doi.org/10.1103/PhysRevLett.19.1264">A Model of Leptons</a>.” That’s the name of the landmark 1967 paper by <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1979/weinberg-bio.html">Steven Weinberg</a> that pulled together quantum mechanics with the vital pieces of knowledge of how particles interact and organized the two into a single theory. It incorporated the familiar electromagnetism, joined it with what physicists called “the weak force” that causes certain radioactive decays, and explained that they were different aspects of the same force. It incorporated <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/2013/higgs-facts.html">the Higgs mechanism</a> for giving mass to fundamental particles. </p>
<p>Since then, the Standard Model has predicted the results of experiment after experiment, including the discovery of several varieties of quarks and of the <a href="https://en.wikipedia.org/wiki/W_and_Z_bosons">W and Z bosons</a> – heavy particles that are for weak interactions what the photon is for electromagnetism. The possibility that <a href="https://en.wikipedia.org/wiki/Neutrino#Mass">neutrinos aren’t massless</a> was overlooked in the 1960s, but slipped easily into the Standard Model in the 1990s, a few decades late to the party.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">3D view of an event recorded at the CERN particle accelerator showing characteristics expected from the decay of the SM Higgs boson to a pair of photons (dashed yellow lines and green towers).</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:3D_view_of_an_event_recorded_with_the_CMS_detector_in_2012_at_a_proton-proton_centre_of_mass_energy_of_8_TeV.png">McCauley, Thomas; Taylor, Lucas; for the CMS Collaboration CERN</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Discovering the Higgs boson in 2012, long predicted by the Standard Model and long sought after, was a thrill but not a surprise. It was yet another crucial victory for the Standard Model over the dark forces that particle physicists have repeatedly warned loomed over the horizon. Concerned that the Standard Model didn’t adequately embody their expectations of simplicity, worried about its mathematical self-consistency, or looking ahead to the eventual necessity to bring the force of gravity into the fold, physicists have made numerous proposals for theories beyond the Standard Model. These bear exciting names like <a href="https://en.wikipedia.org/wiki/Grand_Unified_Theory">Grand Unified Theories</a>, <a href="https://en.wikipedia.org/wiki/Supersymmetry">Supersymmetry</a>, <a href="https://en.wikipedia.org/wiki/Technicolor_(physics)">Technicolor</a>, and <a href="https://en.wikipedia.org/wiki/String_theory">String Theory</a>. </p>
<p>Sadly, at least for their proponents, beyond-the-Standard-Model theories have not yet successfully predicted any new experimental phenomenon or any experimental discrepancy with the Standard Model.</p>
<p>After five decades, far from requiring an upgrade, the Standard Model is <a href="http://artsci.case.edu/smat50/">worthy of celebration</a> as the Absolutely Amazing Theory of Almost Everything.</p><img src="https://counter.theconversation.com/content/94700/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Glenn Starkman receives funding from the Office of Science of the US Department of Energy. He is affiliated with Case Western Reserve University. </span></em></p>
A particle physicist explains just what this keystone theory includes. After 50 years, it’s the best we’ve got to answer what everything in the universe is made of and how it all holds together.
Glenn Starkman, Distinguished University Professor of Physics, Case Western Reserve University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/71742
2017-02-16T10:21:29Z
2017-02-16T10:21:29Z
If atoms are mostly empty space, why do objects look and feel solid?
<figure><img src="https://images.theconversation.com/files/155016/original/image-20170131-3253-44rwcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Why can't we see the spaces?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/atom-icon-palm-391318774?src=OYHZAKupXmgo12-TIByVhw-1-76">Shutterstock</a></span></figcaption></figure><p>Chemist John Dalton proposed the theory that <a href="http://www.iun.edu/%7Ecpanhd/C101webnotes/composition/dalton.html">all matter and objects are made up of particles called atoms</a>, and this is still accepted by the scientific community, almost two centuries later. Each of these <a href="http://www.livescience.com/37206-atom-definition.html">atoms</a> is each made up of an incredibly small nucleus and even smaller electrons, which move around at quite a distance from the centre. </p>
<p>If you imagine a table that is a billion times larger, its atoms would be the size of melons. But even so, the nucleus at the centre would still be far too small to see and so would the electrons as they dance around it. So why don’t our fingers just pass through atoms, and why doesn’t light get through the gaps?</p>
<p>To explain why we must look at the electrons. Unfortunately, much of what we are taught at school is simplified – electrons do not orbit the centre of an atom like planets around the sun, like you may have been taught. Instead, think of electrons like a swarm of bees or birds, where the individual motions are too fast to track, but you still see the shape of the overall swarm.</p>
<h2>Electrons ‘dance’</h2>
<p>In fact, electrons dance – there is no better word for it. But it’s not random dancing – it’s more like ballroom dancing, where they move in set patterns, following steps laid down by a mathematical equation named after <a href="http://www.physlink.com/Education/AskExperts/ae329.cfm">Erwin Schrödinger</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/155022/original/image-20170131-3288-v3fvjj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/155022/original/image-20170131-3288-v3fvjj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/155022/original/image-20170131-3288-v3fvjj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/155022/original/image-20170131-3288-v3fvjj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/155022/original/image-20170131-3288-v3fvjj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=551&fit=crop&dpr=1 754w, https://images.theconversation.com/files/155022/original/image-20170131-3288-v3fvjj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=551&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/155022/original/image-20170131-3288-v3fvjj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=551&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Electrons are like a swarm of birds.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/9/94/The_flock_of_starlings_acting_as_a_swarm._-_geograph.org.uk_-_124593.jpg">John Holmes/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>These patterns can vary – some are slow and gentle, like a waltz whereas some are fast and energetic, like a Charleston. Each electron keeps to the same pattern, but once in a while it may change to another, as long as no other electron is doing that pattern already. No two electrons in an atom can do the same step: this rule is called the <a href="http://abyss.uoregon.edu/%7Ejs/glossary/pauli_exclusion_principle.html">Exclusion Principle</a>. </p>
<p>Although electrons never tire, moving up to a faster step does take energy. And when an electron moves down to a slower pattern it loses energy which it gives out. So when energy in the form of light falls on an electron, it can absorb some energy and move up to a higher, faster “dance” pattern. A light beam won’t get far through our table, since the electrons in all the atoms are eager to grab some energy from the light. </p>
<p>After a very short while they lose this gained energy, perhaps as light again. Changes in the patterns of absorbed and reflected light give reflections and colours - so we see the table as solid.</p>
<h2>Resistance when touched</h2>
<p>So why does a table also feel solid? Many websites will tell you that this is due to the repulsion – that two negatively charged things must repel each other. But this is wrong, and shows you should never trust some things on the internet. It feels solid because of the dancing electrons.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/157108/original/image-20170216-12953-1j19cw2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/157108/original/image-20170216-12953-1j19cw2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157108/original/image-20170216-12953-1j19cw2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157108/original/image-20170216-12953-1j19cw2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157108/original/image-20170216-12953-1j19cw2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157108/original/image-20170216-12953-1j19cw2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157108/original/image-20170216-12953-1j19cw2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The table resistance is strong.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-leaning-on-table-meeting-543916348?src=f0GcHgTOhI_8nwsmejxpww-1-97">Shutterstock</a></span>
</figcaption>
</figure>
<p>If you touch the table, then the electrons from atoms in your fingers become close to the electrons in the table’s atoms. As the electrons in one atom get close enough to the nucleus of the other, the patterns of their dances change. This is because, an electron in a low energy level around one nucleus can’t do the same around the other – that slot’s already taken by one of its own electrons. The newcomer must step into an unoccupied, more energetic role. That energy has to be supplied, not by light this time but by the force from your probing finger.</p>
<p>So pushing just two atoms close to each other takes energy, as all their electrons need to go into unoccupied high-energy states. Trying to push all the table-atoms and finger-atoms together demands an awful lot of energy – more than your muscles can supply. You feel that, as resistance to your finger, which is why and how the table feels solid to your touch.</p><img src="https://counter.theconversation.com/content/71742/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Barlow is affiliated with the Liberal Democrats</span></em></p>
The reason you feel things as solid is all to do with electrons.
Roger Barlow, Research Professor and Director of the International Institute for Accelerator Applications, University of Huddersfield
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/70637
2017-01-06T01:16:03Z
2017-01-06T01:16:03Z
Static electricity’s tiny sparks
<figure><img src="https://images.theconversation.com/files/151794/original/image-20170105-18679-10cdwra.jpg?ixlib=rb-1.1.0&rect=253%2C143%2C2478%2C1676&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Static electricity can cause more than just a bad hair day.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/kretyen/2843109634">Ken Bosma</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Static electricity is a ubiquitous part of everyday life. It’s all around us, sometimes funny and obvious, as when it makes your hair stand on end, sometimes hidden and useful, as when harnessed by the electronics in your cellphone. The dry winter months are high season for an annoying downside of static electricity – electric discharges like tiny lightning zaps whenever you touch door knobs or warm blankets fresh from the clothes dryer.</p>
<p>Static electricity is one of the oldest scientific phenomena people observed and described. Greek philosopher <a href="https://en.wikipedia.org/wiki/Thales_of_Miletus">Thales of Miletus</a> made the first account; in his sixth century B.C. writings, he noted that if amber was rubbed hard enough, small dust particles will start sticking to it. Three hundred years later, <a href="https://en.wikipedia.org/wiki/Theophrastus#Physics">Theophrastus</a> followed up on Thales’ experiments by rubbing various kinds of stone and also observed the “power of attraction.” But neither of these natural philosophers found a satisfactory explanation for what they saw.</p>
<p>It took almost 2,000 more years before the English word “electricity” was first coined, based on the Latin “electricus,” meaning “like amber.” Some of the most famous experiments were conducted by <a href="https://en.wikipedia.org/wiki/Benjamin_Franklin#Electricity">Benjamin Franklin</a> in his quest to understand the underlying mechanism of electricity – which is one of the reasons why his face smiles from the US$100 bill. People quickly recognized electricity’s potential usefulness. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=714&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=714&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=714&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=898&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=898&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151793/original/image-20170105-18647-nvv9rm.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=898&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 amazing flying boy relies on static electricity to wow the crowd.</span>
<span class="attribution"><a class="source" href="https://www.awesomestories.com/asset/view/Stephen-Gray-and-His-Experiments">Frontispiece of Novi profectus in historia electricitatis, post obitum auctoris, by Christian August Hausen (1746)</a></span>
</figcaption>
</figure>
<p>Of course, in the 18th century people mostly made use of static electricity in magic tricks and other performances. For instance, <a href="https://en.wikipedia.org/wiki/Stephen_Gray_(scientist)">Stephen Gray</a>’s “flying boy experiment” became a popular public demonstration: He’d use a <a href="https://en.wikipedia.org/wiki/Leyden_jar">Leyden jar</a> to charge up the youth, suspended from silk cords, and then show how he could turn book pages via static electricity, or lift small objects just using the static attraction.</p>
<p>Building on Franklin’s insights – including his realization that electric charge comes in positive and negative flavors, and that total charge is always conserved – we nowadays understand at the atomic level what causes the electrostatic attraction, why it can cause mini lightning bolts and how to harness what can be a nuisance for use in various modern technologies.</p>
<h2>What are these tiny sparks?</h2>
<p>Static electricity comes down to the interactive force between electrical charges. At the atomic scale, negative charges are carried by tiny elementary particles called electrons. Most electrons are neatly packed inside the bulk of matter, whether it be a hard and lifeless stone or the soft, living tissue of your body. However, many electrons also sit right on the surface of any material. Each different material holds on to these surface electrons with its own different characteristic strength. If two materials rub against each other, electrons can be ripped out of the “weaker” material and find themselves on the material with stronger binding force.</p>
<p>This transfer of electrons – what we know as a spark of static electricity – happens all the time. Infamous examples are children sliding down a playground slide, feet shuffling along a carpet or someone removing wool gloves in order to shake hands.</p>
<p>But we notice its effect more frequently in the dry months of winter, when the air has very low <a href="https://en.wikipedia.org/wiki/Humidity">humidity</a>. Dry air is an electrical insulator, whereas moist air acts as a conductor. This is what happens: In dry air, electrons get trapped on the surface with the stronger binding force. Unlike when the air is moist, they can’t find their way to flow back to the surface where they came from, and they can’t make the distribution of charges uniform again.</p>
<p>A static electric spark occurs when an object with a surplus of negative electrons comes close to another object with less negative charge – and the surplus of electrons is large enough to make the electrons “jump.” The electrons flow from where they’ve built up – like on you after walking across a wool rug – to the next thing you contact that doesn’t have an excess of electrons – such as a doorknob. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151863/original/image-20170105-18653-1ksfhur.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">You’ll feel the electrons jump.</span>
<span class="attribution"><span class="source">Muhammed Ibrahim</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>When electrons have nowhere to go, the charge builds up on surfaces – until it reaches a critical maximum and discharges in the form of a tiny lightning bolt. Give the electrons a place to go – such as your outstretched finger – and you will most certainly feel the zap.</p>
<h2>The power of the mini sparks</h2>
<p>Though sometimes annoying, the amount of charge in static electricity is typically quite little and rather innocent. The voltage can be about 100 times the voltage of typical power outlets. However, these huge voltages are nothing to worry about, since voltage is just a measure of the charge difference between objects. The “dangerous” quantity is current, which tells how many electrons are flowing. Since typically only a few electrons are transmitted in a static electric discharge, these zaps are pretty <a href="http://www.livescience.com/4077-shocking-truth-static-electricity.html">harmless</a>. </p>
<p>Nevertheless, these little sparks can be fatal to sensitive electronics, such as the hardware components of a computer. Small currents carried by only few electrons can be enough to accidentally fry them. That’s why workers in electronic industries have to remain “grounded.” Being grounded just means maintaining a wired connection to the ground, which for the electrons looks like an empty highway “home.” Grounding yourself is easily done by touching a metal component or holding a key in your hand. Metals are very good conductors, and so electrons are quite happy to go there.</p>
<p>A more serious threat is an electric discharge in the vicinity of flammable gases. This is why it’s advisable to ground yourself before touching the pumps at gas stations; you don’t want a stray spark to combust any stray gasoline fumes. Or you can invest in the kind of <a href="https://en.wikipedia.org/wiki/Antistatic_device#Antistatic_wrist_strap">anti-static wristband</a> widely used by workers in the electronic industries to safely ground individuals before they work on very sensitive electronic components. They prevent static buildups using a conductive ribbon that coils around your wrist.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151864/original/image-20170105-18653-1bjt5f0.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"></a>
<figcaption>
<span class="caption">In settings where a few electrons can do big damage, workers wear anti-static wrist straps.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic.mhtml?id=497993332">Wristband image via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<p>In everyday life, the best method to reduce charge buildups is running a humidifier to raise the amount of moisture in the air. Also keeping your skin moist by applying moisturizer can make a big difference. Dryer sheets prevent charges from building up as your clothes tumble dry by spreading a small amount of fabric softener over the cloth. These positive particles balance out loose electrons, and the effective charge nullifies, meaning your clothes won’t emerge from the dryer clingy and stuck to one another. You can rub fabric softener on your carpets to prevent charge buildup too. Last but not least, wearing cotton clothes and leather-soled shoes are the better choice, rather than wool clothing and rubber-soled shoes, if you’ve really had it with static electricity.</p>
<h2>Harnessing static electricity</h2>
<p>Despite the nuisance and possible dangers of static electricity, it definitely has its benefits.</p>
<p>Many everyday applications of modern technology crucially rely on static electricity. For instance, <a href="https://en.wikipedia.org/wiki/Xerography">Xerox</a> machines and photocopiers use electric attraction to “glue” charged tone particles onto paper. <a href="https://en.wikipedia.org/wiki/Air_ioniser#Ionic_air_purifiers">Air fresheners</a> not only make the room smell nice, but they really do eliminate bad odors by discharging static electricity onto dust particles, thus dissembling the bad smell.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=490&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=490&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=490&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=616&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=616&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151865/original/image-20170105-18659-rgnvue.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=616&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Static electricity can attract and trap charged pollution particles before they’re emitted from factories.</span>
<span class="attribution"><span class="source">Muhammed Ibrahim</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Similarly, the <a href="http://www.school-for-champions.com/science/static_uses.htm">smokestacks</a> found in modern factories use charged plates to reduce pollution. As smoke particles move up the stack, they pick up negative charges from a metal grid. Once charged, they are attracted to plates on the other sides of the smokestack that are positively charged. Finally, the charged smoke particles are collected onto a tray from the collecting plates and can be disposed of.</p>
<p>Static electricity has also found its way into nanotechnology, where it is used, for instance, to pick up single atoms by laser beams. These atoms can then be manipulated for all kinds of purposes as in various <a href="https://www.socpedia.com/scientists-take-one-step-closer-to-quantum-computers-with-a-laser-version-of-maxwells-demon">computing</a> applications. Another exciting application in nanotechnology is the control of <a href="https://www.sciencedaily.com/releases/2016/10/161013160408.htm">nanoballoons</a>, which through static electricity can be switched between an inflated and a collapsed state. These molecular machines could one day deliver medication to specific tissues within the body.</p>
<p>Static electricity has seen two and a half millennia since its discovery. Still it’s a curiosity, a nuisance – but it’s also proven to be important for our everyday lives. </p>
<hr>
<p><em>This article was coauthored by Muhammed Ibrahim, a system engineer at an environmental software company. He is conducting collaborative research with Dr. Sebastian Deffner on reducing computational errors in quantum memories.</em></p><img src="https://counter.theconversation.com/content/70637/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sebastian Deffner is affiliated with the Department of Physics at the University of Maryland Baltimore County (UMBC). </span></em></p>
These mini lightning bolts have been known for millennia. Understanding static electricity at the atomic level opens the door for new technologies – as well as ways to cut down on the tiny zaps.
Sebastian Deffner, Assistant Professor of Physics, University of Maryland, Baltimore County
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/67685
2016-10-26T18:02:15Z
2016-10-26T18:02:15Z
Turning diamonds’ defects into long-term 3-D data storage
<figure><img src="https://images.theconversation.com/files/143343/original/image-20161026-11275-1ilzlvw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Diamonds are a data storers' best friend?</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-132329216/stock-photo-3d-abstract-crystal-clear-background-texture.html">Diamond image via www.shutterstock.com</a></span></figcaption></figure><p>With the amount of data storage required for our daily lives growing and growing, and currently available technology being almost saturated, we’re in desparate need of a new method of data storage. The standard magnetic hard disk drive (HDD) – like what’s probably in your laptop computer – has reached its limit, holding a maximum of a few terabytes. Standard optical disk technologies, like compact disc (CD), digital video disc (DVD) and Blu-ray disc, are restricted by their two-dimensional nature – they just store data in one plane – and also by a physical law called the diffraction limit, based on the wavelength of light, that constrains our ability to focus light to a very small volume. </p>
<p>And then there’s the lifetime of the memory itself to consider. HDDs, as we’ve all experienced in our personal lives, may last only a few years before things start to behave strangely or just fail outright. DVDs and similar media are advertised as having a storage lifetime of hundreds of years. In practice this may be cut down to a few decades, assuming the disk is not rewritable. Rewritable disks degrade on each rewrite.</p>
<p>Without better solutions, we face financial and technological catastrophes as our current storage media reach their limits. How can we store large amounts of data in a way that’s secure for a long time and can be reused or recycled?</p>
<p>In our lab, we’re experimenting with a perhaps unexpected memory material you may even be wearing on your ring finger right now: diamond. On the atomic level, these crystals are extremely orderly – but sometimes defects arise. <a href="http://doi.org/10.1126/sciadv.1600911">We’re exploiting these defects as a possible way to store information</a> in three dimensions.</p>
<h2>Focusing on tiny defects</h2>
<p>One approach to improving data storage has been to continue in the direction of optical memory, but extend it to multiple dimensions. Instead of writing the data to a surface, write it to a volume; make your bits three-dimensional. The data are still limited by the physical inability to focus light to a very small space, but you now have access to an additional dimension in which to store the data. Some methods also polarize the light, giving you even more dimensions for data storage. However, most of these methods are not rewritable.</p>
<p>Here’s where the diamonds come in. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=588&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=588&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=588&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=739&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=739&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143325/original/image-20161026-11256-1xuba6g.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=739&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 orderly structure of a diamond, but with a vacancy and a nitrogen replacing two of the carbon atoms.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Diamond_Structure.png">Zas2000</a></span>
</figcaption>
</figure>
<p>A diamond is supposed to be a pure well-ordered array of carbon atoms. Under an electron microscope it usually looks like a neatly arranged three-dimensional lattice. But occasionally there is a break in the order and a carbon atom is missing. This is what is known as a vacancy. Even further tainting the diamond, sometimes a nitrogen atom will take the place of a carbon atom. When a vacancy and a nitrogen atom are next to each other, the composite defect is called a nitrogen vacancy, or NV, center. These types of defects are always present to some degree, even in natural diamonds. In large concentrations, NV centers can impart a characteristic red color to the diamond that contains them.</p>
<p>This defect is having a huge impact in physics and chemistry right now. Researchers have used it to detect the <a href="http://doi.org/10.1126/science.aaa2253">unique nuclear magnetic resonance</a> signatures of <a href="http://doi.org/10.1126/science.aad8022">single proteins</a> and are probing it in a variety of <a href="http://doi.org/10.1038/nature15759">cutting-edge quantum mechanical experiments</a>.</p>
<p>Nitrogen vacancy centers have a tendency to trap electrons, but the electron can also be forced out of the defect by a laser pulse. For many researchers, the defects are interesting only when they’re holding on to electrons. So for them, the fact that the defects can release the electrons, too, is a problem.</p>
<p>But in our lab, we instead look at these nitrogen vacancy centers as a potential benefit. We think of each one as a nanoscopic “bit.” If the defect has an extra electron, the bit is a one. If it doesn’t have an extra electron, the bit is a zero. This electron yes/no, on/off, one/zero property opens the door for turning the NV center’s charge state into the basis for using diamonds as a long-term storage medium.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=595&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=595&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=595&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=747&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=747&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143342/original/image-20161026-11278-1qkd21l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=747&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Starting from a blank ensemble of NV centers in a diamond (1), information can be written (2), erased (3), and rewritten (4).</span>
<span class="attribution"><span class="source">Siddharth Dhomkar and Carlos A. Meriles</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Turning the defect into a benefit</h2>
<p>Previous experiments with this defect have demonstrated some properties that make diamond a good candidate for a memory platform.</p>
<p>First, researchers can selectively change the charge state of an individual defect <a href="http://doi.org/10.1088/1367-2630/15/1/013064">so it either holds an electron or not</a>. We’ve used a green laser pulse to assist in trapping an electron and a high-power red laser pulse to eject an electron from the defect. A low-power red laser pulse can help check if an electron is trapped or not. If left completely in the dark, the defects maintain their charged/discharged status virtually forever. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143340/original/image-20161026-11239-6taoxb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&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 NV centers can encode data on various levels.</span>
<span class="attribution"><span class="source">Siddharth Dhomkar and Carlos A. Meriles</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our method is still diffraction limited, but is 3-D in the sense that we can charge and discharge the defects at any point inside of the diamond. We also present a sort of fourth dimension. Since the defects are so small and our laser is diffraction limited, we are technically charging and discharging many defects in a single pulse. By varying the duration of the laser pulse in a single region we can control the number of charged NV centers and consequently encode multiple bits of information.</p>
<p>Though one could use natural diamonds for these applications, we use artificially lab-grown diamonds. That way we can efficiently control the concentration of nitrogen vacancy centers in the diamond.</p>
<p>All these improvements add up to about 100 times enhancement in terms of bit density relative to the current DVD technology. That means we can encode all the information from a DVD into a diamond that takes up about one percent of the space.</p>
<h2>Past just charge, to spin as well</h2>
<p>If we could get beyond the diffraction limit of light, we could improve storage capacities even further. We have one novel proposal on this front.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143327/original/image-20161026-32322-lvaitv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A human cell, imaged on the right with super-resolution microscope.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/zeissmicro/9132340803/">Dr. Muthugapatti Kandasamy</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Nitrogen vacancy centers have also been used in the execution of what is <a href="http://doi.org/10.1038/NPHOTON.2009.2">called super-resolution microscopy</a> to image things that are much smaller than the wavelength of light. However, since the super-resolution technique works on the same principles of charging and discharging the defect, it will cause unintentional alteration in the pattern that one wants to encode. Therefore, we won’t be able to use it as it is for memory storage application and we’d need to back up the already written data somehow during a read or write step.</p>
<p>Here we propose the idea of what we call charge-to-spin conversion; we temporarily encode the charge state of the defect in the spin state of the defect’s host nitrogen nucleus. Spin is a fundamental property of any elementary particle; it’s similar to its charge, and can be imagined as having a very tiny magnet permanently attached it.</p>
<p>While the charges are being adjusted to read/write the information as desired, the previously written information is well protected in the nitrogen spin state. Once the charges have encoded, the information can be back converted from the nitrogen spin to the charge state through another mechanism which we call spin-to-charge conversion.</p>
<p>With these advanced protocols, the storage capacity of a diamond would surpass what existing technologies can achieve. This is just a beginning, but these initial results provide us a potential way of storing huge amount of data in a brand new way. We’re looking forward to transform this beautiful quirk of physics into a vastly useful technology.</p><img src="https://counter.theconversation.com/content/67685/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Support for this work was provided by National Science Foundation.</span></em></p><p class="fine-print"><em><span>The research is funded by the National Science Foundation</span></em></p>
With current modes up against their limits, we need new data storage solutions. Tiny defects in diamonds’ atomic structure might turn them into a new medium for memory.
Siddharth Dhomkar, Postdoctoral Associate in Physics, City College of New York
Jacob Henshaw, Teaching Assistant in Physics, City College of New York
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/66613
2016-10-06T16:02:03Z
2016-10-06T16:02:03Z
Why insights of Nobel physicists could revolutionise 21st-century computing
<figure><img src="https://images.theconversation.com/files/140743/original/image-20161006-32708-1qazcoz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Control-alt future.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-136209272/stock-photo-binary-orb-with-orbiting-bits-quantum-computing-concept.html?src=VQ61ULcsbQBfWcgxu1NpPQ-1-4">Mopic/shutterstock.com</a></span></figcaption></figure><p>British scientists David Thouless, Duncan Haldane and Michael Kosterlitz <a href="https://theconversation.com/odd-states-of-matter-how-three-british-theorists-scooped-the-2016-nobel-prize-for-physics-66517">won this year’s</a> Nobel Prize in Physics “for theoretical discoveries of topological phase transitions and topological phases of matter”. The reference to “theoretical discoveries” makes it tempting to think their work will not have practical applications or affect our lives some day. The opposite may well be true. </p>
<p>To understand the potential, it helps to understand the theory. Most people know that an atom has a nucleus in the middle and electrons orbiting around it. These correspond to different energy levels. When atoms group into substances, all the energy levels of each atom combine into <a href="https://www.halbleiter.org/en/fundamentals/conductors-insulators-semiconductors/">bands of electrons</a>. Each of these so-called energy bands has space for a certain number of electrons. And between each band are gaps in which electrons can’t flow. </p>
<p>If you apply an electrical charge (a flow of extra electrons) to a material, its conductivity is determined by whether the highest energy band has room for more electrons. If it does have room, the material will behave as a conductor. If not, you need extra energy to push the current of electrons into a new empty band and as a result the material behaves as an insulator. Understanding conductivity is vital to electronics, since electronic products ultimately rely on components that are electric conductors, semiconductors and insulators. </p>
<p>What Thouless, Haldane and Kosterlitz began to predict in the 1970s and 1980s and <a href="http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.95.226801">other</a> theorists have <a href="http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.95.146802">since</a> taken <a href="http://science.sciencemag.org/content/314/5806/1757">forward</a> is that certain materials break this rule. Instead of having a gap between bands in which electrons can’t flow, they have a special energy level between their bands where certain unexpected things are possible. </p>
<p><a href="https://theconversation.com/odd-states-of-matter-how-three-british-theorists-scooped-the-2016-nobel-prize-for-physics-66517">This quality</a> only exists on the surface or edge of these materials, and is very robust. It also depends to some extent on the shape of the material – the topology, as we say in physics. It behaves identically for a sphere and an egg, for example, but would be different for something shaped like a doughnut because of the hole in the middle. The first measurements of this kind of behaviour have been taken for a current along <a href="http://science.sciencemag.org/content/314/5806/1757">the boundary of a flat sheet</a>. </p>
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<a href="https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=327&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=327&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=327&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=411&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=411&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140745/original/image-20161006-32698-ic3g8y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=411&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">Thouless, Haldane and Kosterlitz.</span>
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<h2>Computer power</h2>
<p>The properties of these so-called topological materials could potentially be extremely useful. Electrical currents can move without resistance across their surface, for example, even where a device is moderately damaged. <a href="https://theconversation.com/explainer-what-is-a-superconductor-38122">Superconductors</a> can already do this without having topological properties, but they only work at very low temperatures – meaning you use a lot of energy keeping them cool. Topological materials have the potential to do the same job at higher temperatures. </p>
<p>This has important implications for computing: most of the energy computers currently use is to run ventilators to cool down the heat produced by electrical resistance in the circuits. Remove this heat problem and you potentially make them many times more energy efficient. This could massively reduce their carbon emissions, for instance. It could also lead to batteries with far longer life spans. Researchers are already experimenting with topological materials like cadmium telluride and mercury telluride to bring <a href="http://science.sciencemag.org/content/314/5806/1757">this vision to life</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=471&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=471&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=471&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=592&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=592&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140744/original/image-20161006-32737-u0u6jg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=592&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">Circuits in action.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-403258948/stock-vector-black-abstract-hi-speed-internet-technology-background-illustration-eye-scan-virus-computer.html?src=F50s84SZ_Qp6pxfXBLYszw-1-4">Titma Ongkantong/shutterstock.com</a></span>
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<p>There is also the potential for a major breakthrough in quantum computing. Classical computers encode information by either applying voltage or not applying voltage to a chip. The computer reads this as a 0 or 1 respectively for each “bit” of information. You put these bits together to build up more complex information. This is how the binary system works. </p>
<p>With quantum computing, you deliver information to electrons instead of microchips. The energy levels of these electrons then correspond to zeros and ones just like in classical computers, but in quantum mechanics both can be true at the same time. Without getting into too much theory, this raises the possibility of computers that can process exceedingly large amounts of data in parallel and are therefore much faster. </p>
<p>While the likes of <a href="https://www.newscientist.com/article/mg23130894-000-revealed-googles-plan-for-quantum-computer-supremacy/">Google</a> and <a href="http://www.research.ibm.com/quantum/">IBM</a> are researching how to manipulate enough electrons to create quantum computers that are more powerful than classical computers, one big obstacle is that these computers are very fragile with respect to surrounding “noise”. Whereas classical computers can cope with interference, quantum computers end up producing intolerable numbers of errors because of shaky support frames, stray electrical fields or air molecules hitting the processor even if you hold it in a high vacuum. This is the main reason why we don’t yet use quantum computers in our everyday lives. </p>
<p>One potential solution is to store information in more than one electron, since noise typically affects quantum processors at the level of single particles. Supposing you have five electrons all jointly storing the same bit of information, so long as the majority store it correctly, a disturbance to a single electron won’t undermine the system. </p>
<p>Researchers have been experimenting with this so-called majority voting, but topological engineering potentially offers an easier fix. In the same way as topological superconductors can carry a flow of electricity well enough that it doesn’t get hampered by resistance, topological quantum processors could be robust enough to be insensitive to noise problems. They could yet offer a major contribution to making quantum computing a reality. Researchers in the US <a href="http://www.nature.com/nphys/journal/v5/n1/abs/nphys1151.html">are working</a> on it. </p>
<h2>The future</h2>
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<a href="https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=792&fit=crop&dpr=1 600w, https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=792&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=792&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=995&fit=crop&dpr=1 754w, https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=995&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/140748/original/image-20161006-32713-17flzh9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=995&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">Superdrugs?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-400666111/stock-photo-medicine-bottle-for-injection-in-hand-palm-of-a-doctor-medical-glass-vial-for-vaccination-science-equipment-liquid-drug-or-vaccine-from-treatment-flu-in-laboratory-hospital-or-pharma.html?src=gX9lCJJqucwfDZu29qG_FQ-1-17">Funnyangel/shutterstock.com</a></span>
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<p>It might take between ten and 30 years before scientists become sufficiently good at manipulating electrons to make quantum computing possible, but they open up exciting possibilities. They could simulate the formation of molecules, for example, which is numerically too complicated for today’s computers. This could revolutionise drug research by enabling us to predict what will happen during chemical processes in the body. </p>
<p>To give just one other example, quantum computing has the potential to make artificial intelligence a reality. Quantum machines may be better at learning than classical computers, partly because they might be underpinned by much cleverer algorithms. Cracking AI could be a step change in human existence – for better or worse. </p>
<p>In short, the predictions of Thouless, Haldane and Kosterlitz have the potential to help revolutionise 21st-century computer technology. Where the Nobel committee has recognised the importance of their work in 2016, we are likely to be thanking them many decades into the future.</p><img src="https://counter.theconversation.com/content/66613/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Hartmann 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>
How Messrs Thouless, Haldane and Kosterlitz could hold the key to the future.
Michael Hartmann, Associate Professor of Photonics and Quantum Sciences, Heriot-Watt University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/49025
2015-10-15T04:13:25Z
2015-10-15T04:13:25Z
Benefits of knowing more about neutrinos which pass through our bodies unnoticed
<figure><img src="https://images.theconversation.com/files/98365/original/image-20151014-12654-1q4usks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Neutrinos, we're looking for you! Japan's Super-Kamiokande detector.</span> <span class="attribution"><span class="source">Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo</span></span></figcaption></figure><p>The observation that <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/">neutrinos</a> have mass, which led to the 2015 Nobel Prize for Physics being awarded jointly to Japan’s Takaaki Kajita Japan and Canada’s Arthur McDonald, is important for two key reasons. First, it provides a deeper knowledge of the fundamental tenets of nature. Second, as with any discovery, it comes with innovation in science and technology. </p>
<p>While we know of the existence of neutrinos, not much is known about them. Neutrinos exist in huge numbers in the universe. That is why understanding neutrinos is directly relevant to our knowledge of the universe. </p>
<p>Now that it has been established that neutrinos have <a href="http://www.sciencedaily.com/releases/2015/10/151006083633.htm">mass</a>, we have a key to better understanding how mass is distributed in the universe. Neutrinos may also contribute to understanding why the universe is continuously expanding. </p>
<p>It sits on the similar scale as the discovery of the <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/2013/">Higgs boson</a> at the <a href="http://home.web.cern.ch/topics/large-hadron-collider">Large Hadron Collider</a> at European Organisation for Nuclear Research (<a href="http://home.web.cern.ch/about">CERN</a>), and the future discoveries expected from the <a href="http://www.ska.ac.za/about/project.php">Square Kilometre Array</a> (SKA) project. </p>
<p>Any discovery in experimental science is the result of titanic efforts to overcome technological difficulties and challenges. When the neutrino was first <a href="http://www.pbs.org/wnet/hawking/strange/html/neutrinos.html">postulated</a> in 1930, many thought that it would be mission impossible to detect them, let alone to study its properties – such as its mass.</p>
<p>The relentless need to understand nature better forces scientists to innovate with which to push the boundaries of science and technology. The efforts exerted to demonstrate that neutrinos contain mass have bolstered science and technology in <a href="http://www.cbc.ca/news/technology/canadian-s-nobel-prize-in-physics-highlights-why-basic-science-matters-1.3262835">Canada</a> and <a href="http://www.gmanetwork.com/news/lite/story/539768">Japan</a>. South Africa’s <a href="http://mg.co.za/article/2013-11-27-sa-will-feel-economic-benefits-of-ska-says-director-general">support</a> of projects at CERN, the SKA and other efforts already have a similar effect.</p>
<p>Boosting science and technology via large scientific projects brings the added value of human capacity development in high technology that South Africa is in so much need of.</p>
<h2>What are neutrinos?</h2>
<p>Before answering this question we need to backtrack a bit. Matter is made of <a href="http://education.jlab.org/atomtour/">atoms</a>. Atoms are made of positively charged <a href="http://dictionary.reference.com/browse/nuclei">nuclei</a> and negatively charged <a href="http://dictionary.reference.com/browse/electron">electrons</a> travelling very fast around the nuclei. </p>
<p>The electro-magnetic force holds the electrons in orbit around the nuclei because opposite electric charges attract each other. Nuclei are very heavy compared to electrons and are composed of protons and neutrons. </p>
<p>Neutrinos can be thought of cousins of the electrons, only neutral. Neutrinos share some of the properties of the electrons – for instance, the spin. There is one type of neutrino coupled to the electron, which is called electron neutrino. The electron has an anti-particle, the positron, which has positive electric charge. There is also an electron anti-neutrino.</p>
<p>In nature there are other charged particles that are similar to the electron, which are called muons and taus. These are heavier than the electron. The muons and taus also have two other types of neutrinos respectively. In total we are aware of three types of neutrinos (electron, muon, and tau) and their anti-particles.</p>
<h2>Why are neutrinos elusive?</h2>
<p>Neutrinos do not have electric charge. Therefore, they do not get repelled or attracted to other charged particles in nature. They interact very weakly with matter so they very rarely leave a trace. </p>
<p>Vast amounts of neutrinos <a href="http://timeblimp.com/?page_id=1033">pass through us</a> every day, but we do not feel them because neutrinos hardly ever interact with the atoms that make up our bodies.</p>
<p>Most of the neutrinos that pass through earth come from the sun and are produced by nuclear fusion. These are called solar neutrinos. The other neutrinos are produced as a result of the collision of cosmic particles with the Earth’s atmosphere. These are called atmospheric neutrinos.</p>
<h2>How can we tell that neutrinos have mass?</h2>
<p>There are three types of neutrinos. If neutrinos were massless then they would travel forever unencumbered. If neutrinos have mass then, as they travel, they gradually “disappear” to become a different type of neutrino. </p>
<p>This is referred to as neutrino oscillation and it is a quantum mechanical effect. </p>
<p>For instance, the Sun creates electron neutrinos. By the time neutrinos reach Earth we only observe about one-third of the emitted neutrinos. The remaining two-thirds of the electron neutrinos becomes muon and tau neutrinos. Through this process, it is directly demonstrated that neutrinos have mass.</p>
<h2>Decades of research pay off</h2>
<p>Neutrinos were put forward in 1930 as a means to explain missing energy from a certain type of nuclear reactions. It was not until 1956 that neutrinos were detected unequivocally in laboratory conditions, for which a <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1995/press.html">Nobel Prize in Physics</a> was awarded in 1995. </p>
<p>Scientists from all over the world have not stopped investigating the nature of these elusive particles. Neutrinos were known to be neutral and assumed to be massless. It was not until the late 1990s and early 2000s that experimental techniques became available in order to elucidate if neutrinos have mass. </p>
<p>The latter signifies a major discovery in physics, leading to a Nobel Prize in Physics in 2015. The fact of the matter is that to date we do not really know how neutrinos acquire mass. Unravelling this mystery may lead to other groundbreaking discoveries.</p><img src="https://counter.theconversation.com/content/49025/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bruce Mellado receives funding from the DST, the NRF, Wits research office.</span></em></p>
The Nobel Prize-winning research on neutrinos is expected to push the boundaries of science and technology.
Bruce Mellado, Professor of Physics, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/38697
2015-06-22T10:17:09Z
2015-06-22T10:17:09Z
Plasmonics: revolutionizing light-based technologies via electron oscillations in metals
<figure><img src="https://images.theconversation.com/files/85396/original/image-20150617-23263-svc9sk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The beauty of stained glass – all down to electron oscillations.</span> <span class="attribution"><a class="source" href="https://pixabay.com/en/glass-colorful-glass-mosaic-color-61087/">LoggaWiggler</a></span></figcaption></figure><p>For centuries, artists mixed silver and gold powder with glass to fabricate colorful windows to decorate buildings. The results were impressive, but they didn’t have a scientific reason for how these ingredients together made stained glass. In the early 20th century, the physicist <a href="http://dx.doi.org/10.1016/j.jqsrt.2009.02.022">Gustav Mie</a> figured out that the color of a metal nanoparticle is related to its size and the optical properties of the metal and adjacent materials.</p>
<p>Researchers have only recently figured out the missing piece of this puzzle. Medieval glass workers would be surprised to find out they were harnessing what scientists today call <a href="http://www.nature.com/nphoton/focus/plasmonics/index.html">plasmonics</a>: a new field based on electron oscillations called plasmons.</p>
<h2>Concentrating light</h2>
<p>Plasmonics demonstrates how light can be guided along metal surfaces or within nanometer-thick metal films. It works like this: on an atomic level, metal crystals have a very organized lattice structure. The lattice contains free electrons, not closely associated with the metal atoms, that interact with the light that hits them.</p>
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<a href="https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/85390/original/image-20150617-23223-ed35es.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simplified sketch of electron oscillations (plasmons) at the metal/air interface. Orange and yellow clouds indicate regions with lower and higher electron concentration, respectively. Arrows show electric field lines in and outside of the metal.</span>
<span class="attribution"><span class="source">Hans-Peter Wagner and Masoud Kaveh-Baghbadorani</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>These free electrons collectively start to oscillate with respect to the fixed position of positively charged nuclei in the metal lattice. Like the density of air molecules in a sound wave, the electron density fluctuates in the metal lattice as a plasmon wave. </p>
<p>Visible light, which has a wavelength of approximately half a micrometer, can thus be concentrated by a factor of nearly 100 to travel through metal films just a few nanometers (nm) thick. That’s 1,000 times smaller than a human hair. The new mixed light-electron-wave-state empowers intense light-matter interactions with unprecedented optical properties.</p>
<h2>What can plasmonics do?</h2>
<p>Plasmonics could revolutionize the way computers or smartphones transfer data within their electronic integrated circuits. Data transfer in current electronic integrated circuits happens via the flow of electrons in metal wires. In plasmonics, it’s due to oscillatory motion about the positive nuclei. Data transfer is therefore more time-consuming in the old technology. Since plasmonic data transfer happens with light-like waves and not with a flow of electrons (electrical current) as in conventional metal wires, the data transmission would be superfast (close to the speed of light) – similar to present glass fiber technologies. But plasmonic metal films are more than 100 times thinner than glass fibers. This could lead to faster, thinner and lighter information technologies.</p>
<p>Surface plasmons also are exceptionally sensitive to any material next to the metal film. A low concentration of atoms, molecules or bacteria bound to the metal surface can change the property of its plasmons. This feature can be used for biological and chemical sensing at extremely low concentrations – for instance, to examine polluted water.</p>
<p>If properly designed, multilayers of plasmonic metal/insulator nanostructures form artificial metamaterials, where the Greek word “meta” means “beyond.” Unlike any other material in nature, these metamaterials have a negative index of refraction. That’s a measure of how much light changes its direction when it enters a transparent insulator. Insulators, including glass, have a positive refractive index; they bend light that enters at a certain angle closer to perpendicular to the insulator surface. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=549&fit=crop&dpr=1 600w, https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=549&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=549&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=690&fit=crop&dpr=1 754w, https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=690&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/85392/original/image-20150617-23256-tgr10o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=690&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Light changes its direction when it enters a transparent insulator with positive refractive index or a metamaterial with negative refractive index.</span>
<span class="attribution"><span class="source">Hans-Peter Wagner and Masoud Kaveh-Baghbadorani</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In contrast, multilayered metamaterials bend light to the “opposite” direction. This fascinating property can be used to cloak objects by covering them with a metamaterial wrap. The foil guides the light smoothly around the object instead of reflecting it. Almost unbelievably, the cloaked object becomes invisible.</p>
<p>Other applications include optical superlenses with significantly higher resolution compared to regular optical microscopes. They could allow scientists to see objects as small as about 100 nm in size. That’s about one-tenth as big as a typical germ.</p>
<p>A few proof-of-principle optical cloaks and superlenses do exist. But high resistivity losses in the metal layers which convert the light-electron-wave energy into heat currently limit the feasibility of many applications.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=350&fit=crop&dpr=1 754w, https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=350&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/80549/original/image-20150505-943-1wicqrh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=350&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simplified sketch of a plasmonic metal/organic/semiconductor nanowire heterostructure. The emission from the nanowire generated by the exciting laser beam is used as an energy pump to compensate for resistivity losses in the metal shell. An organic spacer layer of few 10 nm thickness is inserted to control this energy transfer.</span>
<span class="attribution"><span class="source">Hans-Peter Wagner and Masoud Kaveh-Baghbadorani</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Manufacturing plasmonic nanowires</h2>
<p>High resistivity losses are the major issue with plasmonics. To overcome these limitations, we design and fabricate unique plasmonic metal/organic/semiconductor nanowire heterostructures. Our goal is to excite the semiconductor nanowires with an external light source, then use the internal radiation in the nanowires as an energy-pump source to compensate for metallic losses. This way, the nanowires couple light energy in concert with the light-electron-oscillations to the metal film, thus restoring the amplitude of the damped plasmon wave. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/80550/original/image-20150505-951-1386s7c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dr. Hans-Peter Wagner, right, and his doctoral student Masoud Kaveh-Baghbadorani in the organic molecular beam deposition (OMBD) laboratory, Department of Physics, University of Cincinnati.</span>
<span class="attribution"><span class="source">Jay Yocis University of Cincinnati</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We use the organic molecular beam deposition (OMBD) method to coat the semiconductor nanowires with metal/organic multilayers. In the OMBD chamber, organic and metal materials reside in heatable cylindrical cells. We evaporate both organic molecules and metal atoms in heated cells at ultra-high vacuum (which is hundreds of billion times lower than atmosphere pressure). Then we direct the molecular and atom beams we have produced toward the semiconductor nanowire sample. The thickness of the resulting deposited film on the nanowire is controlled by mechanical shutters at the cell openings. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/85547/original/image-20150618-23232-1s8on1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Transmission electron microscope (HRTEM) image of a GaAs-AlGaAs core-shell nanowire coated with nominally 10 nm aluminum quinoline and a 5 to 10 nm thick gold cluster film on top.</span>
<span class="attribution"><span class="source">Melodie Fickenscher (Advanced Materials Characterization Center College of Engineering and Applied Science) University of Cincinnati</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The energy-transfer processes from the optically excited semiconductor nanowire to the plasmon oscillations in the surrounding metal film are studied with <a href="http://dx.doi.org/10.1088/2053-1591/2/4/045001">ultrafast spectroscopic techniques</a>.</p>
<p>Results from our studies will provide a new understanding of light-electron-waves in the novel and unique metal-semiconductor environment. Hopefully, we will open new prospects for designing low-loss or loss-free plasmonic devices. Ideally we want to enable new and important applications in information technologies, biological sensing and national defense. We further envision our investigations having a strong impact in other research fields: for instance, by utilizing the biocompatibility of our hybrid organic/metal structures, by enhancing the light emission in light-emitting diodes and laser structures or by improving light harvesting in photovoltaic devices.</p><img src="https://counter.theconversation.com/content/38697/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hans-Peter Wagner has received research funding from the National Science Foundation in the past.</span></em></p><p class="fine-print"><em><span>Masoud Kaveh-Baghbadorani receives funding from University of Cincinnati Graduate Scholarship, The Mary J. Hanna and Henry Laws Research Fellowships.</span></em></p>
The field of plasmonics has implications for integrated circuits, biosensors, other light-based technologies – even invisibility cloaks.
Hans-Peter Wagner, Associate Professor of Physics, University of Cincinnati
Masoud Kaveh-Baghbadorani, PhD Candidate in Physics, University of Cincinnati
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/34081
2014-12-15T03:45:09Z
2014-12-15T03:45:09Z
An electron’s near-light-speed tour of the Australian Synchrotron
<figure><img src="https://images.theconversation.com/files/66365/original/image-20141204-7280-3v2o0f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">By the time you've read this caption, electrons in the synchrotron storage ring will have travelled a distance equivalent to 41 times around the Earth.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/manfredmajer/13168276114">manfred majer/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>There’s a place in Melbourne where particles routinely whiz around at 99.99998% the <a href="http://www.grc.nasa.gov/WWW/k-12/Numbers/Math/Mathematical_Thinking/how_fast_is_the_speed.htm">speed of light</a> – the <a href="http://www.synchrotron.org.au">Australian Synchrotron</a>. By accelerating charged particles to release extremely intense light known as <a href="http://dictionary.reference.com/browse/synchrotron%20radiation?s=t">synchrotron radiation</a>, the synchrotron gives scientists a mighty toolkit of advanced analytical and imaging techniques. </p>
<p>Depending on the speed of the particles, the radiation released can be infrared, visible or ultraviolet light, or X-rays of varying energy.</p>
<p>So how do these charged particles get to such high speeds? Let’s take a look at the synchrotron and its array of super-powerful magnets that accelerate electrons to close to the speed of light.</p>
<p>Synchrotron radiation also <a href="http://www.ugr.es/%7Ebattaner/escritos/granada_paper.pdf">exists in nature</a>, notably in the outskirts of the <a href="http://www.nasa.gov/multimedia/imagegallery/image_feature_567.html">Crab Nebula</a>, 6,523 <a href="https://theconversation.com/explainer-light-years-and-units-for-the-stars-16995">light-years</a> from Earth, where crowds of electrons travelling at close to the speed of light trace a curved path under the influence of powerful magnetic fields. </p>
<h2>Radiation generation</h2>
<p>From <a href="http://xdb.lbl.gov/Section2/Sec_2-2.html">humble beginnings</a> in the 1940s as an unwanted by-product of particle accelerators, synchrotron radiation has become the power behind numerous practical outcomes of major benefit to Australia.</p>
<p>A good way to explain how radiation is produced when a particle is accelerated is to look at what happens to the electric field around a charged particle when the particle moves.</p>
<p>All charged particles are surrounded by electric fields. Accelerating the charged particle creates fluctuations in the electric field that propagate outwards. As the electric field changes, it in turn generates an associated magnetic field.</p>
<p>These fluctuations manifest as <a href="http://missionscience.nasa.gov/ems/02_anatomy.html">electromagnetic waves</a> which are waves propagated by simultaneous periodic variations of electric and magnetic field intensity. And so an accelerating charge emits electromagnetic radiation, which may include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays or gamma rays. (You can see how the process works using this <a href="http://phet.colorado.edu/sims/radiating-charge/radiating-charge_en.html">interactive simulation</a>.)</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/74n8L5X2YSI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Discover the diverse types of research at the Australian Synchrotron.</span></figcaption>
</figure>
<p>Synchrotron electrons aren’t the only example of accelerating charges emitting electromagnetic radiation. But synchrotron radiation has interesting properties because the electrons are moving at velocities very close to the speed of light.</p>
<p>If you were an electron, you would “see” that you were emitting radiation in all directions. But from the point of view of the mere humans at the synchrotron, relativity means that the radiation is emitted in a very tight forward-facing cone.</p>
<p>Relativity also increases the frequency of the radiation, so most of the light is in the X-ray part of the electromagnetic spectrum, with some ultraviolet, visible and infrared light as well.</p>
<p>The opening angle of the cone of radiation depends on the energy of the electron beam. Higher-energy beams generate cones with smaller opening angles; in other words, tighter cones. These smaller emission angles concentrate the light and make synchrotron radiation extremely bright when seen head-on, which is what most samples get.</p>
<h2>An electron’s journey</h2>
<p>The heart of the Australian Synchrotron is its light source. As used in this context, the term “synchrotron” is in fact short for “synchrotron light source”. To an accelerator physicist, a synchrotron is actually a particular type of particle accelerator. But I digress.</p>
<p>At the Australian Synchrotron, the light source is a maze of high-tech equipment that generates bunches of electrons, accelerates them to almost the speed of light and forces them round a curved path to produce light from X-ray to infrared wavelengths for use in scientific and industrial research programs.</p>
<p>The electrons begin their journey in the electron gun, which works a bit like the cathode ray tubes in old television sets. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.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"></a>
<figcaption>
<span class="caption">Outside …</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.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"></a>
<figcaption>
<span class="caption">… and inside the electron gun.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>They’re liberated from a metal cathode heated to 1,000C and shot into the linear accelerator in bunches of around 100 million electrons spaced just two nanoseconds apart, travelling at more than 640 million km/h, almost 60% of the speed of light. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0gf85P0PiBg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The linear accelerator further accelerates the electrons to more than 100 billion km/h or roughly 99.9987% of the speed of light. The radiowave energy used to speed up the electrons comes from a klystron, a type of power amplifier commonly used in radar and radio/ TV broadcasting.</p>
<figure class="align-center zoomable">
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<figcaption>
<span class="caption">Moving from the electron gun into the start of the linear accelerator.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Next is the booster ring, where large electromagnets steer the electron bunches around a near-circular path and control their shape and size. A radiofrequency cavity increases their energy every time they go past.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/uYcEZ3H5FbE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>After 600 milliseconds and 1.38-million laps, the bunches are travelling at 99.99998% of the speed of light and have 30 times the energy they had when they left the linear accelerator.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.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"></a>
<figcaption>
<span class="caption">The linear accelerator (L) joins the booster ring.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>They’re ready to move into their final home, the storage ring, a long stainless steel vacuum chamber that operates at a pressure similar to the moon’s atmosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.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"></a>
<figcaption>
<span class="caption">Inside the storage ring tunnel.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The electrons circulate in the storage ring for approximately 30-40 hours, travelling the equivalent of more than seven laps around the Earth every second.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/n6ho-tv6XtE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>As they pass through magnets that control their movements, they emit synchrotron radiation, like their counterparts in interstellar space. More radiofrequency cavities add energy to the electrons to compensate for energy lost. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.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"></a>
<figcaption>
<span class="caption">A radiofrequency cavity boosts energy of electron bunches.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Three main kinds of magnet are colour-coded yellow, green or red according to function:</p>
<ul>
<li>yellow dipole (two poles) bending magnets steer the electron bunches and can act as a source of synchrotron radiation</li>
<li>red quadrupole magnets focus the electron bunches</li>
<li>green sextupole magnets help correct for focusing errors and steer the beam on the correct path.</li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.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"></a>
<figcaption>
<span class="caption">The actual storage ring is the metal tube running through the middle of the red and green magnets.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Some experiments require more powerful or more highly coherent synchrotron radiation light than the yellow dipoles can produce. For these, specialised magnets called insertion devices are inserted into the line of storage ring magnets.</p>
<p>Insertion devices consist of a large array of small but very strong magnets that either undulate or wiggle the electron bunches as they pass through. Undulators produce highly intense, highly coherent light compared to dipole radiation, while wigglers produce highly intense, higher energy light.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=587&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=587&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=587&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=738&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=738&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=738&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Insertion devices.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The most powerful insertion device at the Australian Synchrotron is the A$1.3 million superconducting multi-pole wiggler magnet (affectionately called the silver wiggler) that provides X-rays for the imaging and medical beamline.</p>
<h2>In the control room</h2>
<p>The Australian Synchrotron light source is operated and maintained by specialist control room staff and accelerator physicists. They make sure a consistent and reliable supply of high-quality X-ray and infrared photons is available for the thousands of researchers who use the synchrotron’s unique capabilities each year.</p>
<p>The accelerator science team also conducts a research and development program to further improve synchrotron photon characteristics for particular experiments, and contributes to international efforts to pave the way for future machines. </p>
<p>Key results to date include:</p>
<ul>
<li><p>better thermal stability for optical beamline components (from using frequent <a href="http://www.synchrotron.org.au/about-us/australian-synchrotron-development-plan/asdp-accelerator-and-facility-upgrades/top-up-mode-project">top-ups</a> to keep an almost-constant number of electrons in the storage ring rather than twice-daily injections)</p></li>
<li><p>a smaller beam with more photons (due to an electron beam with reduced <a href="http://www.synchrotron.org.au/about-us/our-facilities/accelerator-physics/as-physicists-achieve-new-low">vertical emittance</a>, a measure of the spread of individual particles in a beam) to enable faster data collection from the tiniest of samples, smaller than five micrometres across (one twentieth the width of a typical human hair).</p></li>
</ul>
<p>Three years ago the Australian Synchrotron broke the world record for low vertical emittance in an electron beam, with an electron beam that was only a few micrometres high in places, or as fine as spider silk.</p>
<p>That’s pretty much the end for the electrons, in the capable hands of the accelerator specialists. But what happens to the light the electrons produce is another story.</p><img src="https://counter.theconversation.com/content/34081/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nancy Mills works for The Australian Synchrotron.</span></em></p>
There’s a place in Melbourne where particles routinely whiz around at 99.99998% the speed of light – the Australian Synchrotron. By accelerating charged particles to release extremely intense light known…
Nancy Mills, Science writer, Australian Synchrotron
Licensed as Creative Commons – attribution, no derivatives.