Nonequilibrium damping of the collective motion of homogeneous cold Fermi condensates with Feshbach resonances

作者：Lin Chi Yong^*; Lee Da Shin; Rivers Ray J

来源：Physical Review A, 2012, 85(3): 033643.

DOI：10.1103/PhysRevA.85.033643

Collisionless damping of a condensate of cold Fermi atoms, whose scattering is controlled by a Feshbach resonance, is explored throughout the BCS and Bose-Einstein condensate (BEC) regimes when small perturbations on its phase and amplitude modes are turned on to drive the system slightly out of equilibrium. Using a one-loop effective action, we first recreate the known result that for a broad resonance the amplitude of the condensate decays as t(-1/2) at late times in the BCS regime, whereas it decays as t(-3/2) in the BEC regime. We then examine the case of an idealized narrow resonance, and find that this collective mode decays as t(-3/2) throughout both the BCS and BEC regimes. Although this seems to contradict earlier results that damping is identical for both broad and narrow resonances, the breakdown of the narrow resonance limit restores this universal behavior. More measurably, the phase perturbation may give a shift on the saturated value to which the collective amplitude mode decays, which vanishes only in the deep BCS regime when the phase and amplitude modes are decoupled.

• 出版日期2012-3-29
• 单位东华大学