1+1=3
Tuesday, August 29, 2006
Checking out places to apply for a postdoc or position? Well, welcome to anxiety-land. When you are in a small field, there are very few positions. When you are in a large one, you have too much competition. When you are in between fields, as myself, nobody wants you because you are from the other side of the fence. Not to mention that most jobs (postdoc at least) you get by social networking, so looking at those ads in Physics today is in fact depressing. I am still months away from the ending of my current job, but I wanted to have an early start and ended up with the looking-for-a-job blues. And those rumor mills? Funny when you are not job-hunting, let me tell you. I already applied for a position which I am not going to get, apparently, because now the institution is freezing any new hires. We'll see. 
Anyway, not a good day for blogging positive thoughts I suppose. 

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Posted by fercook to Science at 8/29/2006 10:38:18 AM

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posted by fercook @ 10:43 AM   0 comments links to this post
An article by Rossini, Benenti and Casati. They study two coupled qubits with a chaotic environment. The purpose is to determine if the chaotic environment gives enough complexity to mimic the effect of a many body real environment. The answer is yes, of course, but there are some points in the paper that make it less general than what it could be. In particular, the choice of coupling between system and environment is so that the environment ONLY couples to the states |00> and |11>, leaving in the end an effective spin 1/2 as the system. This is then obscured by the choice of initial state of the system, |phi>=|00>+|11>. With these choices, all the results can basically be described by a Loschmidt echo of the environment evolving with two kicking strengths. For instance, Fig 2 has only "Fermi golden rule" decay of the Loschmidt echo because of the initial state chosen for the environment, a random superposition. To get Lyapunov decay you would need a coherent state or something like that. The rest of the paper is nice, I like the analytical results they are able to obtain. 

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Posted by fercook to Science at 8/29/2006 09:38:25 AM

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posted by fercook @ 9:44 AM   0 comments links to this post
For large values of 1.