tag:theconversation.com,2011:/ca/topics/teleportation-6735/articles
Teleportation – The Conversation
2015-12-17T10:47:56Z
tag:theconversation.com,2011:article/50812
2015-12-17T10:47:56Z
2015-12-17T10:47:56Z
Star Wars inspired me to become an astrophysicist – and I wasn’t disappointed
<figure><img src="https://images.theconversation.com/files/106252/original/image-20151216-25618-19vf3az.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">© 2014 Lucasfilm Ltd. & TM</span></span></figcaption></figure><p>For nearly 40 years, the phrase “a long time ago in a galaxy far, far away” has resonated in popular culture – forever linked to the iconic opening credits of <a href="https://theconversation.com/uk/topics/star-wars">Star Wars</a>. When I watched the movie for the first time in 1978, at the tender age of ten, I was instantly entranced by its visions of alien worlds, lightsaber battles and the mysterious <a href="https://theconversation.com/how-star-wars-music-lets-us-feel-the-force-49337">Force</a> that “binds the galaxy together”. </p>
<p>Star Wars wasn’t the only reason I became an astrophysicist, but it certainly played its part. And so here I find myself four decades later, surveying 13 billion years of cosmic history and mapping events that really did happen a long time ago, in galaxies far, far away.</p>
<p>So how does the real universe compare with what we see on the silver screen? It would be easy to unpick all those places where the science in Star Wars doesn’t hang together, but then few sci-fi and fantasy films would fare well under that kind of forensic analysis. </p>
<p>But “the science of Star Wars” can be considered in a different light if we regard the films simply as fuel for our imaginations, inviting a host of “what if?” questions. Could you really <a href="https://theconversation.com/how-to-build-a-real-lightsaber-51000">build a lightsaber</a>? Could the <a href="https://theconversation.com/theres-more-than-one-way-to-destroy-a-death-star-disrupt-the-system-for-a-start-38238">Death Star</a> actually destroy a planet? Could you use a tractor beam to capture a spaceship? While most such questions flatly can be answered “no”, a little speculation can introduce audiences to some remarkable recent developments in real science.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/106278/original/image-20151216-25606-1x59kw1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/106278/original/image-20151216-25606-1x59kw1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/106278/original/image-20151216-25606-1x59kw1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/106278/original/image-20151216-25606-1x59kw1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/106278/original/image-20151216-25606-1x59kw1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/106278/original/image-20151216-25606-1x59kw1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/106278/original/image-20151216-25606-1x59kw1.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">Future weapons?</span>
<span class="attribution"><span class="source">Lucasfilm</span></span>
</figcaption>
</figure>
<p>Take the question of hyperspace travel, for example. In sci-fi, travelling between the stars needs this convenient plot device because space is really, really big. Even the nearest star to the Sun is more than four light years away (one light year being the distance that light travels in one year, about 10 million million kilometres). Yet according to Albert Einstein’s theory of relativity – which a century ago revolutionised our understanding of space, time and gravity – nothing can travel faster than light. So does this immediately render the Millennium Falcon’s hyperspace jumps complete fantasy?</p>
<p>Let’s consider the other great 20th century revolution, quantum physics. This is what shapes our understanding of the atomic and sub-atomic world. On these scales the universe is “fuzzy”: the laws of physics are governed by uncertainty and randomness and have no respect for Einstein’s cosmic speed limit, with physicists now able to <a href="https://theconversation.com/teleportation-just-got-easier-but-not-for-you-unfortunately-17060">“teleport” sub-atomic particles</a> instantaneously across their laboratories. </p>
<p>For a century, we have striven to unify gravity and quantum physics with (so far, at least) only limited success. But some theories of quantum gravity suppose that on the very tiniest scales space is “<a href="https://theconversation.com/the-universes-resolution-limit-why-we-may-never-have-a-perfect-view-of-distant-galaxies-50993">foamy</a>” due to the fuzziness of the quantum world. It has been suggested that quantum foam may be permeated by “wormholes” that bridge the vast distances of interstellar space. Perhaps this could provide the key to the Falcon’s hyperspace flights.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/106279/original/image-20151216-25600-1rf6mdu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/106279/original/image-20151216-25600-1rf6mdu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=455&fit=crop&dpr=1 600w, https://images.theconversation.com/files/106279/original/image-20151216-25600-1rf6mdu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=455&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/106279/original/image-20151216-25600-1rf6mdu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=455&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/106279/original/image-20151216-25600-1rf6mdu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=571&fit=crop&dpr=1 754w, https://images.theconversation.com/files/106279/original/image-20151216-25600-1rf6mdu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=571&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/106279/original/image-20151216-25600-1rf6mdu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=571&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">If we could travel through wormholes, who knows what we’d find on the other side.</span>
<span class="attribution"><span class="source">© 2014 Lucasfilm Ltd. & TM</span></span>
</figcaption>
</figure>
<p>Unfortunately, however, quantum wormholes are almost unimaginably small, so it’s not clear how a spaceship could pass through one. That’s where movies such as <a href="https://theconversation.com/uk/topics/star-wars">Star Wars</a> (and, for that matter, Christopher Nolan’s <a href="https://theconversation.com/interstellar-gives-a-spectacular-view-of-hard-science-33991">Interstellar</a> – featuring an artificial wormhole found near Saturn) have to call upon a major dose of scientific licence. </p>
<p>But this doesn’t necessarily lead us to a scientific dead end: <a href="https://theconversation.com/the-search-for-dark-matter-and-dark-energy-just-got-interesting-46422">dark energy</a> – the exotic substance that cosmologists believe is driving the accelerated expansion of the universe – could have just the right properties to “blow up” a wormhole and hold it open.</p>
<p>Alas, we’re not even sure yet what dark energy is, far less ready to harness it for building hyperspace drives. But the innate strangeness of our real universe, from teleporting photons to dark matter, means that we shouldn’t completely rule out developing Star Wars-like technology in our distant future. And if it could happen in our future, in a universe of a 100 billion galaxies maybe it already has happened somewhere out there, long, long ago … </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/106281/original/image-20151216-25610-1bd3rkr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/106281/original/image-20151216-25610-1bd3rkr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/106281/original/image-20151216-25610-1bd3rkr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/106281/original/image-20151216-25610-1bd3rkr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/106281/original/image-20151216-25610-1bd3rkr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/106281/original/image-20151216-25610-1bd3rkr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/106281/original/image-20151216-25610-1bd3rkr.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">Distant worlds.</span>
<span class="attribution"><span class="source">© 2014 Lucasfilm Ltd. & TM</span></span>
</figcaption>
</figure>
<p>Arguably the most dramatic astronomical discoveries of the past few decades have come in the search for planets orbiting other stars. In 1978, when the first Star Wars film was released, most astronomers would have agreed these so-called <a href="https://theconversation.com/uk/topics/exoplanets">exoplanets</a> should exist. But it would take nearly 20 years before they were detected. Fast forward to 2015 and we’ve found thousands of them, and are closing in on the “holy grail”: an earth-like planet orbiting a sun-like star at a distance where liquid water could exist. We have even found a “Tatooine”: the roughly Saturn-sized <a href="http://www.space.com/12963-tatooine-planet-2-suns-star-wars-kepler-16b.html">Kepler 16b</a> orbiting a twin-star system in the constellation of Cygnus.</p>
<p>Could Kepler 16b be the home to Banthas, Jawas and the occasional Jedi knight? Probably not: with a likely surface temperature of minus 100, the ice planet Hoth is perhaps a better match. But as Episode VII fires the imaginations of a whole new generation of fans (and maybe a few budding astrophysicists) I look forward to falling under the Star Wars spell once more – content in the knowledge that the real universe is much richer, more surprising and just plain weirder than anything we will see on the screen.</p><img src="https://counter.theconversation.com/content/50812/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Hendry receives funding from receives research funding from the Science and Technology Facilities Council.
</span></em></p>
Four decades later, I find myself surveying 13 billion years of cosmic history and mapping events that really did happen a long time ago in galaxies far, far away.
Martin Hendry, Professor of Gravitational Astrophysics and Cosmology, University of Glasgow
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/17060
2013-08-18T20:20:07Z
2013-08-18T20:20:07Z
Teleportation just got easier – but not for you, unfortunately
<figure><img src="https://images.theconversation.com/files/29318/original/znfhnr3h-1376544108.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Teleportation is still well and truly entrenched in science fiction, unless you're a photon.</span> <span class="attribution"><span class="source">Photon™</span></span></figcaption></figure><p>Thanks to two studies <a href="http://www.nature.com/nature/current_issue.html">published in Nature last Thursday</a>, the chance of successful teleportation has considerably increased. Which is a good thing, right?</p>
<p>Whether or not you’ve ever been on a long-haul flight, you’ve probably fantasised about being able to magically disappear from one place and reappear in another. And a natural question for a physicist is whether there is any way to achieve this in practice.</p>
<p>In fact, something known as “quantum teleportation” became a <a href="http://www.nature.com/nature/journal/v390/n6660/abs/390575a0.html">reality in 1997</a>. This first demonstration was for particles of light (<a href="http://en.wikipedia.org/wiki/Photon">photons</a>). Since then, physicists have also applied teleportation to other very small things, for example <a href="http://physicsworld.com/cws/article/news/2009/jan/22/atoms-teleport-information-over-long-distance">single atoms</a>.</p>
<p>So when can we expect to just teleport ourselves to our chosen destination? You might want to sit down for this. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=816&fit=crop&dpr=1 600w, https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=816&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=816&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1025&fit=crop&dpr=1 754w, https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1025&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/29305/original/cn4zgy95-1376540717.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1025&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Wonderlane</span></span>
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</figure>
<p>The first step to teleporting a person is measuring and recording the position, direction of motion and energy of every particle in the body, which would require more data storage than will ever be available - much, much more. </p>
<p>In fact, a <a href="http://www.wired.com/wired/archive/3.11/krauss_pr.html">conservative estimate</a> would mean you’d need about 10<sup>22</sup> gigabytes (1 followed by 22 zeros) of hard drive space. That’s a stack of hard drives about 20 <a href="http://www.grc.nasa.gov/WWW/k-12/Numbers/Math/Mathematical_Thinking/how_long_is_a_light_year.htm">light-years</a> tall. </p>
<p>Proxima Centauri, the nearest star to Earth other than the sun, is around <a href="http://heasarc.nasa.gov/docs/cosmic/nearest_star_info.html">four light-years away</a>. </p>
<p>Worse, we have no method to even make these measurements, let alone reconstruct a person based on the data. So we can forget about teleporting people.</p>
<h2>Knowing enough - but not too much</h2>
<p>What about something really simple – such as a single particle? How about an atom, or a photon? How can these be teleported?</p>
<p>The problem here was thought to be the <a href="http://theconversation.com/explainer-heisenbergs-uncertainty-principle-7512">Heisenberg uncertainty principle</a>, a cornerstone of quantum mechanics that limits what you can know. </p>
<p>It might sound counter-intuitive, but if you try to measure the position of a single atom you will change its velocity. If you find out exactly how fast it is moving, then you won’t know where it is. </p>
<p>The problem is, if you want to teleport a particle, this is precisely the information you want to measure and transmit. </p>
<p>A physicist would call this information the “state” of the particle. If you’re not allowed to measure the complete state of the particle, teleportation looks impossible.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/29317/original/2q74vg7v-1376544051.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/29317/original/2q74vg7v-1376544051.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/29317/original/2q74vg7v-1376544051.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/29317/original/2q74vg7v-1376544051.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/29317/original/2q74vg7v-1376544051.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/29317/original/2q74vg7v-1376544051.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/29317/original/2q74vg7v-1376544051.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">jasoneppink</span></span>
</figcaption>
</figure>
<p>So the key to teleportation is not knowing too much. As long as the measurements that you make do not reveal the position or velocity, then you have a loophole that allows you to circumvent the uncertainty principle. </p>
<p>What if you could disturb the particle before you measure it, so you never know its state, and then subtract off that disturbance at the other end to recreate the original state of the particle? </p>
<p>This was the breakthrough realisation that American physicist <a href="http://goo.gl/fSyvZ">Charles Bennett</a> had in 1993. The key was to disturb the particle you want to teleport in a particular way. You can do this by using a pair of <a href="https://theconversation.com/wind-up-your-clockwork-universe-einstein-if-you-can-524">quantum-entangled particles</a>. </p>
<p>These particles are linked to each other so that if you measure the state of one of the entangled pair, you learn about the state of the other half of the pair. </p>
<h2>Alice and Bob</h2>
<p>In the standard description of teleportation, <a href="http://en.wikipedia.org/wiki/Alice_and_Bob">Alice is teleporting something to Bob</a>. Alice uses one of the entangled particles to measure the state of the input particle. She records what she measures and sends the information to Bob. </p>
<p>Bob can’t tell what the state of the particle was, because the entanglement used in the measurement hides the true nature of the state. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=528&fit=crop&dpr=1 600w, https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=528&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=528&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=663&fit=crop&dpr=1 754w, https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=663&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/29306/original/bgy6ytt2-1376540774.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=663&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>What Bob can do, however, is use the information from Alice to modify the state of the other entangled particle. In this way he can recreate the exact state of the particle Alice originally measured. </p>
<p>This is how quantum teleportation works. Most photon experiments teleport over a metre or so inside a lab, although there has recently been a <a href="http://blog.physicsworld.com/2012/05/22/quantum-teleportation-record-b/">demonstration over 143km</a> in the Canary Islands.</p>
<h2>A sense of security</h2>
<p>It turns out that quantum teleportation is not just a good party trick. The nature of the communication between Alice and Bob in this system is pretty interesting. </p>
<p>The information that Alice measures and sends to Bob cannot be used to recreate the input state without the other entangled particle. That means Eve the eavesdropper can’t spy on Alice’s measurement and get the information for herself. </p>
<p>The entangled pair is unique, so only Bob can recreate the original state. Immediately you have a technique for secure communication. </p>
<p>If you encode information in your particles, measure them with one part of an entangled state and then send the information to Bob, you have cryptography that is made strong by quantum physics. You really can’t crack it by any means, unless you have the other part of the entangled pair.</p>
<h2>Reasons to be cheerful</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=414&fit=crop&dpr=1 600w, https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=414&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=414&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=520&fit=crop&dpr=1 754w, https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=520&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/29322/original/3x7nm39z-1376545696.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=520&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 128-qubit superconducting adiabatic quantum optimisation processor chip.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>Teleportation has many other uses in <a href="http://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">quantum information systems</a>. </p>
<p>These are <a href="https://theconversation.com/quantum-computers-coming-to-a-store-near-you-16320">proposed methods</a> for building computers and communication networks that use quantum mechanics as a core part of their functionality and have enormous potential to provide secure communications and high-speed computing. </p>
<p>The catch is that any time you want to move quantum information from one place to another in one of these systems, you can’t just measure the information and send it to the next part of the process, since the measurement will destroy the information. Instead, you can teleport it.</p>
<h2>Back to Nature</h2>
<p>The two papers published together in this week’s Nature show something very important. </p>
<p>Until now, teleporting photons of light using the method described above has been probabilistic, because you couldn’t synchronise the arrival of the entangled photons with the arrival of the photon to be measured. </p>
<p>On the odd occasion when the photons aligned, the measurement would only work half the time. That means every time you try and teleport your information it will only work very occasionally - much less than 1% of the time. </p>
<p>If you have a lot of back-to-back-teleporting circuits in your quantum computer or quantum network, the chances of them all working together will become vanishingly small. </p>
<p>These two most recent experiments show deterministic quantum teleportation in two different systems so that the process is no longer probabilistic. Instead it can, in principle, work every time a photon is ready to be teleported. </p>
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<a href="https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/29303/original/ybb4rjvx-1376540332.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="attribution"><span class="source">mercurialn</span></span>
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<p><a href="http://www.nature.com/nature/journal/v500/n7462/full/nature12366.html">One of the new studies</a> – by researchers from Japan and Germany – shows how it is possible to teleport photons of light that are in the <a href="https://theconversation.com/explainer-what-is-the-electromagnetic-spectrum-8046">infrared spectrum</a>, just below the wavelength visible to the human eye.</p>
<p>The <a href="http://www.nature.com/nature/journal/v500/n7462/full/nature12422.html">other experiment</a> – by researchers in Switzerland and Australia – demonstrates teleportation of microwave photons with a frequencies between 4 and 7 GHz. </p>
<p>Neither system is production-ready, in the sense that they are both just proof of principle experiments. Although the teleportation is no longer probabilistic, it is still not 100% efficient - a 40% chance of success in the case of the infrared system and 25% in the case of the microwave system.</p>
<p>Still, this is a vast improvement on less than 1% that was previously possible with photons. Long-haul flights will continue for some time yet, but the new experiments represent a milestone on the long road to building a functional quantum information system.</p><img src="https://counter.theconversation.com/content/17060/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Buchler receives funding from the ARC centre of Excellence for Quantum Computation and Communication technology (CQC2T).</span></em></p>
Thanks to two studies published in Nature last Thursday, the chance of successful teleportation has considerably increased. Which is a good thing, right? Whether or not you’ve ever been on a long-haul…
Ben Buchler, Research Fellow in Quantum Science, Australian National University
Licensed as Creative Commons – attribution, no derivatives.