Tuesday, August 22, 2006

Recently in cond-mat

Two recent papers that I find particularly interesting (both of which have now come out in print as well)....
cond-mat/0603442 - Sela et al., Fractional shot noise in the Kondo regime (also PRL 97, 086601 (2006)).
As I've discussed before, shot noise is noise that results from the fact that charge comes in discrete chunks. For strongly correlated systems, when the low energy excitations of the system can't be nicely described as single quasiparticles that act like "free" electrons, there can be dramatic signatures in the shot noise. These authors argue that such an effect should be present in the shot noise that results when current flows through a quantum dot in the Kondo regime - that is, when an unpaired spin on the dot is strongly entangles with the conduction electrons of the leads via higher order tunneling processes. The claim is that the effective charge of the carriers measured via shot noise is actually 5/3e, rather than simply e. This would be very neat.

cond-mat/0608459 - Koppens et al., Driven coherent oscillations of a single electron spin in a quantum dot (also Nature 442, 766 (2006)).
Once again, the Kouwenhoven group at Delft turns out a gorgeous piece of experimental work. This time, not only do they succeed in electrically measuring single-electron spin resonance. They go further, and demonstrate that they can coherently manipulate the spin, placing it into, e.g., a superposition of "up" and "down", and watching the Rabi oscillations back and forth. Wow. This is a real tour de force experiment, when you consider that the whole system needs to work at mK temperatures.

2 comments:

Anonymous said...

Can you give us your thoughts on how certain groups like Delft people manage to produce papers in science and nature two weeks in a row? Humble human beings like us would really like to learn the secret since there are widespread rumours that editors in science and nature reject papers that are unlikely to get citations. Is there any truth to that? How much of this business is "science" and how much of it is "politics"?

Doug Natelson said...

Disclaimer: Bear in mind that I've yet to get a paper into either of those journals (though I'm co-author on one hopefully coming soon)....

First, have a large group with a good number of very talented people, plus a base of strong technical support. The Delft effort is large, and they have some first-rate infrastructure and technicians. The same is true of the nanostructures group at the Weizman. Next, become facile at writing in the appropriate style for Science and Nature. It's quite different from PRL or Nano Letters or JACS. There is no doubt in my mind that there are certain authors that the editors like - they consistently do interesting stuff in hot areas, and write in the appropriate style. Alivisatos, Whitesides, Kouwenhoven, Dekker - these guys are clearly very good at this stuff.