Again I only was able to see the morning session today (and will be at Rice until Thursday pm). This means I'll miss the big "BCS@50" plenary session. However, here are a couple of talks that I did get to see....
First, T. Senthil started the day with a talk about spin liquids. This is a theoretically deep concept that I would love to understand better. The basic idea is that one can recast the interacting many-body problem in terms of new excitations of spinons (chargeless spin 1/2 excitations). The cost of doing this is that the spinons have "infinitely nonlocal" statistical correlations. However, these interactions can be made to look simple by introducing some effective gauge "charge" for the spinons and some effective gauge "magnetic field" - then the correlations look like the Aharonov-Bohm effect in this gauge language. If this sounds vague, it's partly because I don't really understand it. The upshot is that the spinons can be fermionic, and therefore have a Fermi surface, and this leads to nontrivial low temperature properties, particularly in systems where the whole weakly interacting quasiparticle picture falls apart. If anyone can point me to a good review article about this, I'd appreciate it.
There were a couple of other strong theory talks. Natan Andrei talked about a general approach to quantum impurities driven out of equilibrium (e.g., as in a quantum dot in the Kondo regime at large source-drain bias). Strong correlations + nonequilibrium is a tough nut to crack. Andrei argued that one can rewrite the problem in terms of scattering of initial states via simple phase shifts, provided that one picks the right (nasty, complicated) basis for the initial states that somehow wraps up the strong correlation effects. This choice of basis is apparently a form of the Bethe Ansatz, which I also need to understand better.
On the experimental side, besides my talk, Gleb Finkelstein from Duke gave a very nice talk about Kondo physics in carbon nanotube quantum dots. The really clever aspect of the work is that, through careful engineering of the contacts to the tube, the actual leads to the dot + the tunnel barriers + the dot itself are all formed out of the same nanotube. As a result the tunnel barriers preserve the special band structure symmetry (SO(4)) of the tube and the leads, leading to profoundly neat effects in transport.