tag:blogger.com,1999:blog-2167545615231111772024-03-05T11:53:46.029-08:00Matt Purkeypile on Quantum Computer ProgrammingA collection of thoughts on quantum computer programming and related topics.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.comBlogger127125tag:blogger.com,1999:blog-216754561523111177.post-8067186263136970322012-01-17T20:41:00.000-08:002012-01-17T20:48:09.730-08:00D-Wave Python Dev KitLooks like D-Wave has a developer kit setup for Python, as outlined in this tutorial on their site: <a href="http://www.dwavesys.com/en/dev-tutorial-finance.html">http://www.dwavesys.com/en/dev-tutorial-finance.html</a>. Looks like they realized the same thing I did: to really be applicable for the commercial environment quantum computers need to be programmed via frameworks and not new quantum specific languages.<br /><br />When I started work on <a href="https://cove.purkeypile.com/">Cove</a> I actually started doing the implementation in both Python and C#. I quickly realized that was creating a lot of unnecessary work for myself and quickly abandoned the Python implementation. My reason for settling on C# was largely that the libraries could be used by multiple languages. However, I still think Python is a great candidate- Python's readability and simple learning curve make it a natural choice.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com1tag:blogger.com,1999:blog-216754561523111177.post-86552264576435315832011-12-12T20:18:00.000-08:002011-12-12T20:22:28.689-08:00Quantum chip out of BristolThey've made some recent progress at Bristol University, making a small quantum chip. Some articles:<br /><ul><li><a href="http://news.techeye.net/chips/scientists-conjure-up-tiny-reconfigurable-quantum-chip">TechEye</a></li><li><a href="http://www.crazyengineers.com/quantum-computing-materialized-on-single-chip-1438/">Crazy Engineers</a></li><li><a href="http://www.zmescience.com/research/studies/quantum-computing-breakthrough-quantum-photonic-chip-created/">ZME Science</a></li><li><span style="display: block;" id="formatbar_Buttons"><span class=" down" style="display: block;" id="formatbar_CreateLink" title="Link" onmouseover="ButtonHoverOn(this);" onmouseout="ButtonHoverOff(this);" onmouseup="" onmousedown="CheckFormatting(event);FormatbarButton('richeditorframe', this, 8);ButtonMouseDown(this);">And of course, <img src="img/blank.gif" alt="Link" class="gl_link" border="0" />the <a href="http://www.bristol.ac.uk/news/2011/8109.html">Bristol press release</a>.<br /></span></span></li></ul>Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com1tag:blogger.com,1999:blog-216754561523111177.post-92020094947771957292011-11-15T20:50:00.001-08:002011-11-15T20:51:53.186-08:00Q & A with Seth Lloyd<a href="http://www.popsci.com/science/article/2011-10/seth-lloyd-particle-man">Here's</a> a short question and answer with Seth Lloyd of MIT in Popular Science. As one would expect, this is more of a primer being in PopSci.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-76659201686675896462011-10-25T21:11:00.000-07:002011-10-25T21:12:26.591-07:00Caltech awarded funding for quantum research<a href="http://www.eurekalert.org/pub_releases/2011-10/ciot-ca101711.php">Caltech awarded $12.6 million for new Institute for Quantum Information and Matter</a>.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-30515079290962965732011-10-25T21:07:00.001-07:002011-10-25T21:09:23.367-07:00More progress<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqScdZvfeo-HvKKEftLQ7Oz_fPGbyQGlPvZxWqKsR2D4FBZYLae3VmJDqryVRxQ43PAIYH1Cz4u15ygvyubFnlwE0I7PztbuNIyNhuAAx_bZLV8_a05tbzSfHEWnXh6VTR8nIHGOrvgY4/s1600/NSF.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 320px; height: 201px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqScdZvfeo-HvKKEftLQ7Oz_fPGbyQGlPvZxWqKsR2D4FBZYLae3VmJDqryVRxQ43PAIYH1Cz4u15ygvyubFnlwE0I7PztbuNIyNhuAAx_bZLV8_a05tbzSfHEWnXh6VTR8nIHGOrvgY4/s320/NSF.jpg" alt="" id="BLOGGER_PHOTO_ID_5667648002352637154" border="0" /></a><br /><br />More progress, from the National Science Foundation: <a href="http://www.nsf.gov/news/news_summ.jsp?cntn_id=122029&org=NSF&from=news">Tiny crystal towers enlighten understanding of photon emission, could inspire diamond microchips for quantum computing</a>. (Image from the release.)Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-59379364185831834992011-08-27T09:22:00.000-07:002011-08-27T09:25:34.316-07:00Maintaining Entanglement for an Hour<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQUwx6AlE7DFN9NN_AujIeJ540qOdQTGwPy_amfxjj-uGqtIUp0EKUYueecrlcILhPRYroT2ifsa54q3Kr_7bCG3Qrjq81p_gcpCCrVAd4P75IT7SumaLryUdaF2IWS8qjai40q9oEZFw/s1600/entanglement-300.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 300px; height: 193px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQUwx6AlE7DFN9NN_AujIeJ540qOdQTGwPy_amfxjj-uGqtIUp0EKUYueecrlcILhPRYroT2ifsa54q3Kr_7bCG3Qrjq81p_gcpCCrVAd4P75IT7SumaLryUdaF2IWS8qjai40q9oEZFw/s400/entanglement-300.jpg" alt="" id="BLOGGER_PHOTO_ID_5645572692097633922" border="0" /></a>
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<br />Maintaining quantum states for any length of time is one of the big challenges in quantum computing. So <a href="http://www.nbi.ku.dk/english/news/news11/quantum_optical_link_sets_new_time_records_/">this news</a> about maintaining entanglement for an hour is encouraging. (Image from the article.)
<br />Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-6521746846728346872011-07-25T19:40:00.000-07:002011-07-25T19:43:13.812-07:00Suppressing decoherenceSome progress towards <a href="http://www.blogger.com/post-create.g?blogID=216754561523111177">suppressing decoherence</a>, a major stumbling block towards physical implementations of quantum computers.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-51348660088636535512011-07-16T08:53:00.001-07:002011-07-16T08:54:41.190-07:00Dave Bacon Moves to GoogleI came across <a href="http://www.linkedin.com/in/dabacon">this</a>: Dave Bacon, previously at the University of Washington, has moved on to Google. Is the commercialization of quantum computing on the horizon?Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com5tag:blogger.com,1999:blog-216754561523111177.post-62298489148712724982011-07-16T08:47:00.000-07:002011-07-16T08:49:44.633-07:00Michael Nielsen on Open ScienceMichael Nielsen of [1] fame on open science:<br /><br /><object width="640" height="390"><param name="movie" value="http://www.youtube.com/v/DnWocYKqvhw&rel=0&hl=en_US&feature=player_embedded&version=3"></param><param name="allowFullScreen" value="true"></param><param name="allowScriptAccess" value="always"></param><embed src="http://www.youtube.com/v/DnWocYKqvhw&rel=0&hl=en_US&feature=player_embedded&version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowScriptAccess="always" width="640" height="390"></embed></object><br /><br />[1] Nielsen, Michael A., and Isaac L. Chuang. Quantum Computation and Quantum Information. 2008. 1 ed. Cambridge, UK: Cambridge University Press, 2000. 8.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-46240168292092763332011-06-28T19:56:00.001-07:002011-06-28T19:58:18.855-07:00Quantum computing named one of the hottest 10 fields in scienceThe Financial Times has named quantum computing one of the 10 hottest fields in science in a <a href="http://www.ft.com/cms/s/2/bedd6da8-9d37-11e0-997d-00144feabdc0.html#axzz1Qd7YAHUT">recent article</a>.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-21427901000756879992011-06-22T19:44:00.000-07:002011-06-22T19:49:59.938-07:00Paper: Verification of Quantum ProgramsI'm of the opinion that formal verification of programs has a limited set of applications, in large part due to the "good enough" software principle. Nonetheless, it is nice to see work in the quantum programming area. Here's a just posted paper on arXiv: <a href="http://arxiv.org/abs/1106.4063">Verification of Quantum Programs</a> by Ying, Yu, Feng, and Duan.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-58416590945310364562011-06-19T10:16:00.000-07:002011-06-19T10:20:38.449-07:00QIS-XML: An Extensible Markup Language for Quantum Information Science<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4j1bG77Xg-ApX0vN1zIthlNwU0aW7UU7K31Pz984kUtjw0QwLkyJLhA2yq3fZmYPNusSRyLtDBX-m_Gm-iga5bQZ8JYpgqU3Q1gvcObFtNYR0MUOz9nW9De_u2jAIW2tyOOflawYT97k/s1600/xform.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 548px; height: 167px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4j1bG77Xg-ApX0vN1zIthlNwU0aW7UU7K31Pz984kUtjw0QwLkyJLhA2yq3fZmYPNusSRyLtDBX-m_Gm-iga5bQZ8JYpgqU3Q1gvcObFtNYR0MUOz9nW9De_u2jAIW2tyOOflawYT97k/s400/xform.png" alt="" id="BLOGGER_PHOTO_ID_5619981881509118610" border="0" /></a><br />By Pascal Heus out of George Mason University: <a href="http://arxiv.org/abs/1106.2684">QIS-XML: An Extensible Markup Language for Quantum Information Science</a>.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com1tag:blogger.com,1999:blog-216754561523111177.post-23692906809657216592011-06-06T20:48:00.000-07:002011-06-06T20:51:41.030-07:00Cooling through computationErasing data generates heat. For example, an And gate can erase data because if you get a false (0) you don't know if the inputs were both false or if just one of them were 0. Hence quantum computers need to perform reversible operations. <a href="http://physicsworld.com/cws/article/news/46202">Here</a> is some pretty cool work on <span style="font-style: italic;">cooling</span> computers by the computations they perform.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-282890230471503792011-06-01T20:19:00.000-07:002011-06-01T20:21:16.412-07:00D-Wave sells quantum computer to Lockheed MartinFor those who have not seen it yet, D-Wave has sold its first quantum computer to Lockheed Martin for 10 million. Here are a few of the many articles about it:<br /><ul><li><a href="http://blogs.discovermagazine.com/80beats/2011/06/01/the-worlds-first-quantum-computer-finds-a-buyer-but-questions-about-its-abilities-remain/comment-page-1/">Discover Magazine</a></li><li><a href="http://www.ibtimes.com/articles/154429/20110530/lockheed-martin-d-wave-quantum-annealing-processor-patents-quantum-computing.htm">International Business Times</a><br /></li></ul>Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-4003245634909842912011-05-18T20:45:00.001-07:002011-05-18T20:54:21.725-07:00Verdal on the cover of the new Scientific American<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWWc0M91dVfebmD8wjfghpZ-wJ5BfXmjKYUkwM9BTOUaMBmUpSFbWgMpyvKF-bdRt5khcpoqECDuMAW8nAoRU29L99rrhD1Mc6rOzbyrpyf9PM0i5ZvTQtgBXOW2wKvq80V__aVRENwsQ/s1600/SciAm-June2011.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 210px; height: 278px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWWc0M91dVfebmD8wjfghpZ-wJ5BfXmjKYUkwM9BTOUaMBmUpSFbWgMpyvKF-bdRt5khcpoqECDuMAW8nAoRU29L99rrhD1Mc6rOzbyrpyf9PM0i5ZvTQtgBXOW2wKvq80V__aVRENwsQ/s400/SciAm-June2011.png" alt="" id="BLOGGER_PHOTO_ID_5608270209517736194" border="0" /></a><br /><br />Vlatko Verdal, of [1] fame, wrote an article titled "<a href="http://www.scientificamerican.com/article.cfm?id=living-in-a-quantum-world">Living in a Quantum World</a>", which made the cover of this month's (June 2011) cover of Scientific American.<br /><br /><span style="font-weight: bold;">References</span><br />[1] Vedral, Vlatko. Introduction to Quantum Information Science. 1 ed. Oxford, Great Britain: Oxford University Press, 2006.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-80121347438798167662011-05-18T20:24:00.001-07:002011-05-18T20:30:02.595-07:00More D-Wave ClaimsFor those who have not seen it yet, <a href="http://news.sciencemag.org/sciencenow/2011/05/controversial-computer-is-at-lea.html">D-Wave is making some new claims</a>. I've been skeptical since 2007, and still feel the same way. I think Scott Aaronson described the situation well <a href="http://www.scottaaronson.com/blog/?p=639">in his blog</a>, as he usually does about D-Wave.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-13515712311466993042011-05-02T19:55:00.000-07:002011-05-02T19:58:23.566-07:00Information sharing at the quantum limitOut of the <a href="http://www.mpq.mpg.de/cms/mpqhome/index.html">Max Planck Institute</a> yesterday: <a href="http://www.mpq.mpg.de/cms/mpq/en/news/press/pdf/2011/PR_11_05_01.pdf">Information sharing at the quantum limit</a> (A photon transfers its secrets onto a single atom).Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-43649765216932230422011-05-02T19:49:00.000-07:002011-05-02T19:51:49.344-07:00UC Santa Barbara to get $7.5 million for quantum computingUC Santa Barbara is getting <a href="http://pacbiztimes.com/index.php?option=com_content&task=view&id=2335&Itemid=1">$7.5 million for quantum computing research</a> from the Defense Department. The work will be lead by Awschalom.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-66251746450322231202011-03-24T19:48:00.000-07:002011-03-24T19:55:48.396-07:00Quantum Public Key Encryption<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3D7-bCiLyfwaboOnHlqMdelFk-XgxEDsv2Y2boUtMZnLJmprssImyxxwE7dNRvgTupsst_-9gQo8wmfrbHx68MvdUiRLTvh8BI3SuCG2c0H9Fb7vOXUghKgwSBD4uiynfNVLTQiaEKg8/s1600/PublicKey.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 215px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3D7-bCiLyfwaboOnHlqMdelFk-XgxEDsv2Y2boUtMZnLJmprssImyxxwE7dNRvgTupsst_-9gQo8wmfrbHx68MvdUiRLTvh8BI3SuCG2c0H9Fb7vOXUghKgwSBD4uiynfNVLTQiaEKg8/s400/PublicKey.png" alt="" id="BLOGGER_PHOTO_ID_5587845623765819122" border="0" /></a><br /><br />One of the most cited benefits of a quantum computer is that it can factor, therefore breaking many current public key encryption systems. That makes this recent paper by Kawachi, Koshiba, Nishimura, and Yamakami certainly interesting: a quantum version of public key encryption. <a href="http://www.technologyreview.com/blog/arxiv/26531/?p1=Blogs">Here's a brief article in MIT Technology Review</a>, and <a href="http://arxiv.org/abs/quant-ph/0403069">the paper on arXiv</a>. The abstract:<br /><blockquote>We introduce a computational problem of distinguishing between two specific quantum states as a new cryptographic problem to design a quantum cryptographic scheme that is "secure" against any polynomial-time quantum adversary. Our problem, QSCDff, is to distinguish between two types of random coset states with a hidden permutation over the symmetric group of finite degree. This naturally generalizes the commonly-used distinction problem between two probability distributions in computational cryptography. As our major contribution, we show that QSCDff has three properties of cryptographic interest: (i) QSCDff has a trapdoor; (ii) the average-case hardness of QSCDff coincides with its worst-case hardness; and (iii) QSCDff is computationally at least as hard as the graph automorphism problem in the worst case. These cryptographic properties enable us to construct a quantum public-key cryptosystem, which is likely to withstand any chosen plaintext attack of a polynomial-time quantum adversary. We further discuss a generalization of QSCDff, called QSCDcyc, and introduce a multi-bit encryption scheme that relies on similar cryptographic properties of QSCDcyc. </blockquote><br />(Image from the paper.)Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-17309338211599477082011-03-24T19:41:00.001-07:002011-03-24T19:43:27.920-07:00Quantum Information in the MainstreamIt looks as if quantum information is starting to enter the mainstream: US News and World Report has <a href="http://www.usnews.com/science/articles/2011/03/24/diamond-could-store-quantum-information">an article on using diamonds for quantum memory</a>.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com1tag:blogger.com,1999:blog-216754561523111177.post-10443765113707548722011-03-12T15:40:00.001-08:002011-03-12T15:51:13.341-08:00Classical Simulation of Quantum Adiabatic Algorithms using Mathematica on GPUs<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhduCgHfTku305AbmqQ2_KQFo5aktV8D_xMpnKw6dXNMyTU_PD6Xy9L_5vauLXPdpKFURdy4lteRmD4D43XJYulOUmE12l1d-p4GUxS4EsTanVfIzrQRpDrNuU3yf6uB6rxwJGaQorhtNQ/s1600/gpu.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 310px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhduCgHfTku305AbmqQ2_KQFo5aktV8D_xMpnKw6dXNMyTU_PD6Xy9L_5vauLXPdpKFURdy4lteRmD4D43XJYulOUmE12l1d-p4GUxS4EsTanVfIzrQRpDrNuU3yf6uB6rxwJGaQorhtNQ/s400/gpu.png" alt="" id="BLOGGER_PHOTO_ID_5583344982479195266" border="0" /></a><br /><br />Simulation of quantum computers is what allows us to test quantum software on a limited scale. Therefore this recent paper by Díaz-Pier, Venegas-Andraca, and Gómez-Muñoz, <a href="http://arxiv.org/abs/1103.1399">Classical Simulation of Quantum Adiabatic Algorithms using Mathematica on GPUs</a> is of interest. The abstract:<br /><blockquote>In this paper we present a simulation environment enhanced with parallel processing which can be used on personal computers, based on a high-level user interface developed on Mathematica\copyright which is connected to C++ code in order to make our platform capable of communicating with a Graphics Processing Unit. We introduce the reader to the behavior of our proposal by simulating a quantum adiabatic algorithm designed for solving hard instances of the 3-SAT problem. We show that our simulator is capable of significantly increasing the number of qubits that can be simulated using classical hardware. Finally, we present a review of currently available classical simulators of quantum systems together with some justifications, based on our willingness to further understand processing properties of Nature, for devoting resources to building more powerful simulators. </blockquote>(Image is figure 1 from the paper.)Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-81820590919540515462011-03-12T15:28:00.000-08:002011-03-12T15:30:50.951-08:00More physical progress<a href="http://www.uq.edu.au/news/index.html?article=22803">More physical progress</a>, out of the University of Queensland.Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-64399094598064147182011-02-27T07:49:00.000-08:002011-02-27T07:50:32.076-08:00Solid state qubitsMore progress on physical implementations of quantum computers: <a href="http://spectrum.ieee.org/nanoclast/semiconductors/nanotechnology/could-super-conducting-graphene-quantum-dots-lead-to-solidstate-qubits">solid state qubits</a>?Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-26568442663389380312011-02-16T20:06:00.000-08:002011-02-16T20:10:18.667-08:00arXiv: Advances in Quantum Metrology<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpzgRhgJ5HA5iiiV_RD9MhtrChVMwzjwKywYuTZHFf7PamVRlf6XFRc8apFw8qD-9CCLcRLYngzFhyphenhyphenSIdGp-r0jazO4fdsdQ9dHplm-ZwBuAo5H9F2U5e9ogDH9Jc-53yNe1noZ2qrQG8/s1600/weather.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 358px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpzgRhgJ5HA5iiiV_RD9MhtrChVMwzjwKywYuTZHFf7PamVRlf6XFRc8apFw8qD-9CCLcRLYngzFhyphenhyphenSIdGp-r0jazO4fdsdQ9dHplm-ZwBuAo5H9F2U5e9ogDH9Jc-53yNe1noZ2qrQG8/s400/weather.png" alt="" id="BLOGGER_PHOTO_ID_5574505941345309506" border="0" /></a><br /><br />From <a href="http://arxiv.org/">arXiv</a>: <a href="http://arxiv.org/abs/1102.2318">Advances in Quantum Metrology</a> by Giovannetti, Lloyd, Maccone. It is a preliminary version, but still an intriguing topic. The abstract:<br /><br /><blockquote>In classical estimation theory, the central limit theorem implies that the statistical error in a measurement outcome can be reduced by an amount proportional to n^(-1/2) by repeating the measures n times and then averaging. Using quantum effects, such as entanglement, it is often possible to do better, decreasing the error by an amount proportional to 1/n. Quantum metrology is the study of those quantum techniques that allow one to gain advantages over purely classical approaches. In this review, we analyze some of the most promising recent developments in this research field. Specifically, we deal with the developments of the theory and point out some of the new experiments. Then we look at one of the main new trends of the field, the analysis of how the theory must take into account the presence of noise and experimental imperfections. </blockquote><br />(The image is figure 2 from the paper.)Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0tag:blogger.com,1999:blog-216754561523111177.post-68380482579826845632011-02-07T20:46:00.000-08:002011-02-07T20:53:42.746-08:00arXiv: Experimental Extraction of Secure Correlations from a Noisy Private State<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXKrbqL2ktGo37FdFbGGdWI2r97_qctArwlF73wnno2qdrnGhEgkycGa5aXyEVJtJhHVftDDWkGIP43Wfm1ivEseRI1n_oBFTssIsl2bQC2xl4u86Z12OL2HEpGWNkuOhy5QAjwo79brA/s1600/1.png"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 311px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXKrbqL2ktGo37FdFbGGdWI2r97_qctArwlF73wnno2qdrnGhEgkycGa5aXyEVJtJhHVftDDWkGIP43Wfm1ivEseRI1n_oBFTssIsl2bQC2xl4u86Z12OL2HEpGWNkuOhy5QAjwo79brA/s400/1.png" alt="" id="BLOGGER_PHOTO_ID_5571177349260680770" border="0" /></a><br /><br />Recently revised on <a href="http://arxiv.org/">arXiv</a>: <a href="http://arxiv.org/abs/1010.4575">Experimental Extraction of Secure Correlations from a Noisy Private State</a> by Dobek, Karpinski, Demkowicz-Dobrzanski, Banaszek, and Horodecki:<br /><br /><blockquote>We report experimental generation of a noisy entangled four-photon state that exhibits a separation between the secure key contents and distillable entanglement, a hallmark feature of the recently established quantum theory of private states. The privacy analysis, based on the full tomographic reconstruction of the prepared state, is utilized in a proof-of-principle key generation. The inferiority of distillation-based strategies to extract the key is exposed by an implementation of an entanglement distillation protocol for the produced state. </blockquote><br />There is a short summarizing article <a href="http://www.alphagalileo.org/ViewItem.aspx?ItemId=95024&CultureCode=en">here</a> too:<br /><blockquote>The latest experiment with photonic entanglement, conducted by Polish physicists working in the consortium National Laboratory for Quantum Technologies, may be of vital importance to make quantum cryptography a more widespread technology. It has been demonstrated that secret communication based on quantum phenomena, which guarantees unconditional security against eavesdropping, can be also realized using sources of quantum entanglement considered until now to be too corrupt.</blockquote>(Image taken from the paper.)Matt Purkeypilehttp://www.blogger.com/profile/07820536834251212868noreply@blogger.com0