Collisionless modes of a trapped Bose gas

TL;DR

This paper calculates the excitation frequencies of specific modes in a trapped Bose gas within the collisionless regime, accounting for temperature effects and noncondensate dynamics, and compares results with experimental data.

Contribution

It introduces a coupled non-linear Schrödinger and Boltzmann equation approach that includes noncondensate dynamics, satisfying the Kohn theorem and extending previous models.

Findings

Spectrum is strongly temperature dependent

Results agree with experimental measurements

Method accounts for noncondensate cloud dynamics

Abstract

We calculate the excitation frequencies of the m=0 monopole and m=2 quadrupole modes in the collisionless regime by solving a non-linear Schroedinger equation for the condensate, coupled to a collisionless Boltzmann equation for the quasiparticles. Since the dynamics of the noncondensate cloud is also taken into account, the theory satisfies the Kohn theorem. The spectrum turns out to be strongly temperature dependent and we compare our results with experiment.