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Two-Fluid Hydrodynamics for a Trapped Weakly-Interacting Bose Gas

E. Zaremba·A. Griffin·T. Nikuni
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Abstract

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.

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E. Zaremba, A. Griffin, T. Nikuni. 1997-05-14. Two-Fluid Hydrodynamics for a Trapped Weakly-Interacting Bose Gas. https://doi.org/10.1103/physreva.57.4695

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