1+1=3
Wednesday, May 31, 2006
The holiday has me very delayed on everything, including reading. 
 
  • quant-ph/0605169, decoherence of a bell pair in a random matrix environment. I gave just a quick look at the paper, seems interesting (although I should refresh my random matrix theory...)
  • quant-ph/0605173. Actually, I printed this but haven't read it yet. I am interested in its connection to Clifton, Bub and Halvorson derivation of quantum mechanics from information constrains.
  • Lecture Notes in Quantum Mechanics, by Doron Cohen. They are worth a look, specially on the approach to new subjects. In any case, Doron writes too entangled for my taste (at least in his papers). The notes seem more clear.
  • quant-ph/0504141, another go at the "self-decoherence" in chaotic systems from Giulio Casati. Didn't Berry say enough about correlators in chaotic systems? Apparently not. I like that in this paper the fidelity is well expressed as a "time-interferometry" experiment, something I have been mulling about lately. The paper has a lot of other ideas that seem nice too, worth reading.
  • Finally, two papers that I'll read in my (every day diminishing) free time. Loop Quantum programming, and  quantum mechanics as a global optimization by nature (I'll have to keep the jokes about this one until I read it).


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Posted by fercook to Science at 5/31/2006 08:27:27 AM

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posted by fercook @ 8:30 AM   0 comments links to this post
Friday, May 19, 2006
posted by fercook @ 8:52 AM   0 comments links to this post
Monday, May 15, 2006

I received my Cryptex from the Google: Da Vinci Code!!! I am one of the lucky 10000 finalists....

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Posted by fercook to Extras at 5/15/2006 07:42:00 PM

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posted by fercook @ 7:43 PM   0 comments links to this post
Saturday, May 13, 2006
Talking of the (devil) time

I just saw this article, [quant-ph/0605069] Time as a quantum observable. I'll have to read it now...

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Posted by fercook to Science at 5/13/2006 07:36:51 PM

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posted by fercook @ 7:36 PM   0 comments links to this post
Thursday, May 11, 2006
I have been daydreaming about the role of time in quantum mechanics, clearly without bothering to look in the literature. I find it difficult to believe that a "time operator", that is a conjugate of the Hamiltonian, cannot be defined. The usual argument is that since time is unbounded, so would be the energies and therefore you end up with an unphysical system. However, I am doubtful since, for instance, you cannot define a suitable conjugate operator to position when the position is bounded (open boundary conditions I mean, if you have periodic bc momentum is well defined but it has discrete eigenvalues). In light of this, and the similar to x and p relation between time and energy, I don't fully understand what is the problem. Anyway, I found this article where it is argued that the confusion arises originally from mixing x, the operator position, and q, the eigenvalues of this operator. In classical mechanics the difference accounts to x being the coordinates of points in space, and q the coordinates of a point particle in space. With this in mind, some funny time operators are constructed, which applied to some clock-systems have time as eigenvalues. It works pretty well from what can I see. The energy spectrum of these clocks can be unbounded of course (which wouldn't pose a problem if they are isolated if I understood correctly), or bounded if we choose a periodic time (a round clock of course :). 

All very nice, I will have to think about this for a while to see if it makes full sense...

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Posted by fercook to Science at 5/11/2006 02:10:14 PM

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posted by fercook @ 2:12 PM   0 comments links to this post
Monday, May 08, 2006
  • Quantum Dissipation and Decoherence via Interaction with Low-Dimensional Chaos: a Feynman-Vernon Approach; M.V.S. Bonanca, M.A.M. de Aguiar; quant-ph/0605037
  • The Dynamics of Entanglement in the Adiabatic Search and Deutsch Algorithms; K. Choy, G. Passante, D. Ahrensmeier, M.E. Carrington, T. Fugleberg, R. Kobes, G. Kunstatter; quant-ph/0604066
  • Decoherence by engineered quantum baths; Davide Rossini, Tommaso Calarco, Vittorio Giovannetti, Simone Montangero, Rosario Fazio; quant-ph/0605051
  • Sweeping from the superfluid to Mott phase in the Bose-Hubbard model; Ralf Schützhold, Michael Uhlmann, Yan Xu, Uwe R. Fischer; cond-mat/0605121


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Posted by fercook to Science at 5/08/2006 10:14:21 AM

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posted by fercook @ 10:16 AM   0 comments links to this post
Thursday, May 04, 2006
This one of course I like, perhaps there is a more paternal reason to it.

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Posted by fercook to Movies and all at 5/04/2006 09:18:01 PM

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posted by fercook @ 9:20 PM   0 comments links to this post
Wednesday, May 03, 2006

Probably the best short video I have seen in a lot, a lot of time.
Check it out here (it wouldn't hurt to look for a version with more quality, although the idea is already so good.)
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Posted by fercook to Movies and all at 5/03/2006 08:13:47 PM

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posted by fercook @ 8:18 PM   0 comments links to this post
Tuesday, May 02, 2006
I am writing a research interests statement to apply for a job. I didn't know it was so difficult ! I got these nice pointers from Penn U
Also, a very good resource for job hunting from Science magazine.

Posted by fercook to Science at 5/02/2006 08:20:57 AM

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posted by fercook @ 8:23 AM   0 comments links to this post
I believed this quote was from E.P. Wigner, however I found out that many people attribute it to Einstein, others to Jane Austin, Ernest Hemingway, Ralph Waldo Emerson, and so on. Correctly, some people point out that it is a stripped-down version of Occam's razor, and that probably it is another good orphan quote.

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Posted by fercook to Science at 5/02/2006 08:14:16 AM

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posted by fercook @ 8:17 AM   0 comments links to this post
Monday, May 01, 2006
  • Time-dependence of correlation functions following a quantum quench, Calabrese and Cardy cond-mat/0601225
  • Decay of Loschmidt Echo Enhanced by Quantum Criticality, H.T. Quan, Z. Song, X.F. Liu, P. Zanardi, C.P. Sun, quant-ph/0509007
  •  Semiclassical approach to Bose-Einstein condensates in a triple well potential, S. Mossmann, C. Jung, quant-ph/0604158
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Posted by fercook to Science at 5/01/2006 10:47:42 AM

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posted by fercook @ 10:49 AM   0 comments links to this post
For large values of 1.