Acoustic attenuation probe for fermion superfluidity in ultracold atom   gases
  Dilute gas Bose-Einstein condensates (BEC's), currently used to cool fermionic atoms in atom traps, can also probe the superfluidity of these fermions. The damping rate of BEC-acoustic excitations (phonon modes), measured in the middle of the trap as a function of the phonon momentum, yields an unambiguous signature of BCS-like superfluidity, provides a measurement of the superfluid gap parameter and gives an estimate of the size of the Cooper-pairs in the BEC-BCS crossover regime. We also predict kinks in the momentum dependence of the damping rate which can reveal detailed information about the fermion quasi-particle dispersion relation. 
Sergio Gaudio (1)(2), B. Mihaila (2), K. B. Blagoev (2), K. S. Bedell   (1), Eddy Timmermans (2) (1) (Department of Physics,...