Finite temperature excitations of Bose gases in anisotropic traps

TL;DR

This paper investigates how the frequencies of excitations in a weakly interacting Bose gas vary with trap anisotropy, using a combined mode expansion and semiclassical approach to evaluate the EZC approximation.

Contribution

It introduces a combined mode expansion and semiclassical method to analyze finite temperature excitations in anisotropic traps, assessing the EZC approximation's accuracy.

Findings

Mode frequencies depend on trap anisotropy.

The combined method improves accuracy over previous models.

EZC approximation is validated for certain conditions.

Abstract

The mode frequencies of a weakly interacting Bose gas in a magnetic trap are studied as a function of the anisotropy of the trap. As in earlier works the generalized Hartree-Fock-Bogoliubov equations within the Popov approximation (HFB-Popov) are used for our calculations. The new feature of our work is the combined use of a mode expansion in a finite basis and a semiclassical approximation of the highly excited states. The results are applied to check the accuracy of the recently suggested equivalent zero-temperature condensate (EZC) approximation which involves a much simpler model.