AN EVALUATION OF SUPER-FLUID DENSITY         s AS A FUNCTION OF        c T T FOR BCS-BEC CROSSOVER REGIME

Abstract

In a Fermi gas with a Fashbach resonance, one can tune the strength of the paring interaction by adjusting the threshold energy of Feshbach resonance. The super-fluid density s  is always equal to the total carrier density  at T  0 which it vanishes at the super-fluid phase transition c T . These properties are satisfied in both Fermi and Bose super-fluid. There is a crucial difference between s
 in a Fermi superfluid and that in a Bose superfluid. In a mean field BCS theory originates from the thermal dissociation of cooper pairs. There it was observed that that if one increases the strength of the pairing interaction BCS type normal fluid density dominated by quasi-particl  change into BES type normal fluid density dominated by Bogoliubov collective excitations. As super-fluid density s
 plays an important role in two fluid hydrodynamics these evaluated results would be useful in the study of dynamical properties in the BCS-BEC crossover region at finite temperature.