Hendrik Weimer's Quantenblog

Having fun with science and technology.

  • Getting PSfrag-ged EPS files to work with Inkscape

    Posted: 2009-08-13 06:35

    When preparing figures for papers or other scientific content I routinely use PSfrag for inserting LaTeX commands. Sometimes I would like to edit the result with Inkscape to add some fancy stuff, but unfortunately most of the time Inkscape cannot open the created EPS file. I have written a short guide describing how to finally get it to work.

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  • US Government Works Still Protected Internationally

    Posted: 2009-01-20 18:52

    Recently on debian-legal someone asked whether you may freely distribute works created by a US government entity in other countries than the US. Well, I've asked a guy working on international copyright law, and unfortunately the answer was "no". Even though these works do not enjoy copyright protection in the US, they are still protected in other countries.

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  • 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.

  • 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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  • 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.

  • Few Banks Use Extended Validation Certificates

    Posted: 2008-08-04 06:55

    The latest thing against phishing are extended validation (EV) certificates. Supported by Firefox 3 and Internet Explorer 7, these certificates promise that the site has gone through a more extensive validation of its owner than ordinary SSL certificates. However, when it comes to market adoption after almost two years availability, these new certificates have failed badly. Only thirty percent of the world's largest banks already present an EV certificate in their online banking application.

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    [ security ]

  • OpenJDK in Debian

    Posted: 2008-07-29 12:02

    Over a year after Sun's initial release of OpenJDK as free software, Debian successfully managed to build a version of OpenJDK using only free software. Apparently, the hard part was bootstrapping OpenJDK with the GNU Java compiler gcj. And it seems they did a very good job, as there are hardly any drawbacks compared to the proprietary version.

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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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    [ physics ]

  • Liberation Fonts Increase Document Interoperability

    Posted: 2008-06-24 06:33

    Ever wondered why a Word document you received looks garbled when opening it in OpenOffice.org under GNU/Linux? Most likely, this is not a bug in OOo's conversion algorithms, but a problem of missing fonts. Most Word documents use fonts like "Arial" or "Times New Roman", which are copyrighted by Microsoft. While Microsoft used to distribute these so-called "core fonts" for non-Windows users, they no longer do so. There are still places where you can get them legally, but of course this is not a free-as-in-speech solution. Therefore, these fonts are not available by default in many GNU/Linux distros.

    While the individual glyphs of a font can be copyrighted, their metrics (i.e., their spatial dimensions) cannot be, and therefore one can create a free set of fonts that look different than their proprietary counterparts, but otherwise behave the same when it comes to things like linebreaking, hyphenation, etc. Red Hat has done just that, and some time ago released the Liberation fonts.

    However, due to licensing issues not all major GNU/Linux distros included the Liberation fonts. But after a long wait and the persistent work by several people these issues have finally been settled and the Liberation fonts have been accepted into the Debian archive. Other distros are expected to follow suit soon.

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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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  • Copyright 2006--2011 Hendrik Weimer. This document is available under the terms of the GNU Free Documentation License. See the licensing terms for further details.