%0 Journal Article
%T Two-Fluid Hydrodynamics for a Trapped Weakly-Interacting Bose Gas
%A E. Zaremba
%A A. Griffin
%A T. Nikuni
%J Physics
%D 1997
%I arXiv
%R 10.1103/PhysRevA.57.4695
%X We derive the coupled equations of motion for the condensate (superfluid) and non-condensate (normal fluid) degrees of freedom in a trapped Bose gas at finite temperatures. Our results are based on the Hartree-Fock-Popov approximation for the time-dependent condensate wavefunction and an assumption of local equilibrium for the non-condensate atoms. In the case of a uniform weakly-interacting gas, our formalism gives a microscopic derivation of the well-known two-fluid equations of Landau. The collective modes in a parabolically trapped Bose gas include the analogue of the out-of-phase second sound mode in uniform systems.
%U http://arxiv.org/abs/cond-mat/9705134v1