On the Ratio of the Viscosity to Entropy Density for Quantum Gases in the Unitary Limit Speaker(s): Andre LeClair
Abstract: In the socalled unitary limit of quantum gases, the scattering length diverges and the theory becomes scale invariant with dynamical exponent z=2. This point occurs precisely at the crossover between strongly coupled BEC and BCS. These systems are currently under intense experimental study using cold atoms and Feshbach resonances to tune the scattering length. We developed a new approach to the statistical mechanics of gases in higher dimensions modeled after the thermodynamic Bethe ansatz, i.e. based on the exact 2body Smatrix. Calculations of the critical temperature Tc/T_F = 0.1 are in good agreement with experiments and MonteCarlo studies. We also calculated the ratio of viscosity to entropy density and obtained 4.7 times the conjectured lower bound of 1/4 pi, in good agreement with very recent experiments. We also present evidence for a strongly interacting version of BEC.
Date: 16/08/2011  10:50 am
Collection: Integrability in Gauge/String Theories Tech Note: extra slides at beginning (auto)
