Hendrik Weimer's Quantenblog

Having fun with science and technology.

  • libquantum 1.0.0 and 1.1.0 released

    Posted: 2008-09-09 06:27

    Two new versions of libquantum have been released. The 1.1.0 development release adds support for exact diagonalization, while the 1.0.0 stable release contains only bug fixes. Further information can be found on the libquantum website.

  • libquantum 0.9.1 released

    Posted: 2007-09-03 07:13

    libquantum 0.9.1 has been released. The new release adds an interface for time-evolution of arbitrary Hamiltonians using a fourth-order Runge-Kutta algorithm. The license has been changed to GPLv3 and several bugs have been fixed. Further information can be found on the libquantum website.

  • The Quantum Machine that Both Works and Doesn't

    Posted: 2007-08-22 06:32

    As some of you may know, I wrote my diploma thesis on transport in quantum thermodynamics. Related to this work, we now put up a paper on arXiv, describing how to incorporate the concepts of work and heat, which are well-known from the classical world, into the quantum realm.

    It turns out that if you do it properly, you get some remarkable consequences, like a machine that both works and does not at the same time. These strange things arise (hardly surprising) from non-commuting observables in quantum mechanics.

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  • Strongly Interacting Rydberg Atoms

    Posted: 2008-06-28 12:32

    Rydberg atoms are atoms with a large principle quantum number. One possibility to create them is to excite ground state atoms with lasers. They are very sensitive to electric fields, so if you bring them close together they will experience very strong interactions due to static or induced electric dipoles.

    We have now put a paper onto the arXiv, where we investigate the properties of the strongly interacting regime. We have found some interesting links between Rydberg physics and concepts originally coming from condensed matter physics.

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  • Read Scientific Papers from Anywhere

    Posted: 2007-01-03 12:56

    Accessing scientific papers online is great because it spares you the way to the library. Unfortunately, most journals make their articles available only to paying subscribers (contrary to Open Access). So if you want to read an article at home or while on a conference you have a problem. This posting shows you how to access it anyway just by clicking on the download link in a journal. Read more

  • Qinf: A Free Quantum Information Suite for Maxima

    Posted: 2008-10-22 20:17

    I have dropped Mathematica in favor of Maxima some time ago in order to escape from obscure bugs remaining unfixed and licensing troubles, and have not regretted it since. Now I just came across Qinf, which is a free (as in GPLv2) quantum information suite for Maxima. While the package is still under development it already contains quite a lot useful functions like partial traces, entropy calculation, operator expansion. So if you use Qinf instead of another package relying on a proprietary CAS, you can prevent your code from being trapped.

  • Moore's Law for Quantum Computers

    Posted: 2011-09-07 06:03

    By looking at the history of quantum computing experiments, one finds an exponential increase in the number of qubits, similar to Moore's law for classical computers. Quantum computing power doubles about every six years, with quantum computers for real applications arriving in between nine and twelve years if this trend continues.

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  • Listen to Quantum Computer Music

    Posted: 2010-04-13 18:55

    I spent some time playing around with libquantum, the free quantum simulation library, and created two musical compositions that represent the inner workings of a quantum computer. So if you'd like to know what a quantum computer sounds like, here's your chance!

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  • Academic Journals Resolve Copyright Conflict over Wikipedia

    Posted: 2008-10-06 18:43

    The American Physical Society (APS) is one of the most important publishers in physics, well-known for its Physical Review journals, including their flagship Physical Review Letters. Like most other publishers, APS requires authors to transfer copyright, meaning you may not use the materials elsewhere without permission from the APS. This created trouble for some researchers who wanted to put their research on Wikipedia and other open content sites because the APS refused to permit them to do so. Fortunately, the APS has now changed their copyright policy, thus resolving the issue.

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  • A Rydberg Quantum Simulator

    Posted: 2010-03-15 16:20

    A universal quantum simulator would be something quite useful to have, as it allows to simulate the behavior of any quantum-mechanical system efficiently. We have been able to show that one can build such a device with strongly interacting Rydberg atoms, as reported in our paper having just appeared in Nature physics.

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  • Pseudonymity is Different from Anonymity

    Posted: 2008-06-06 06:43

    A paper (also available here) published yesterday in Nature analyzes moving patterns of humans based on position data provided by a European mobile network operator. While the paper itself is very interesting and provides new insights it also raises serious privacy concerns, and maybe even legal troubles for the telco in question.

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