Undamped nonequilibrium dynamics of a nondegenerate Bose gas in a 3D isotropic trap

TL;DR

This paper models the damping of monopole modes in a non-degenerate 3D Bose gas within an isotropic trap, revealing that anharmonicities, dephasing, and collisions jointly cause damping, supported by Monte Carlo simulations matching experimental data.

Contribution

It introduces a realistic model incorporating trap anharmonicities to explain monopole mode damping in a Bose gas, validated by Monte Carlo simulations.

Findings

Damping arises from dephasing and collisional relaxation.

Anharmonic trap effects significantly influence collective mode damping.

Model aligns well with experimental observations.

Abstract

We investigate anomalous damping of the monopole mode of a non-degenerate 3D Bose gas under isotropic harmonic confinement as recently reported by the JILA TOP trap experiment [D. S. Lob- ser, A. E. S. Barentine, E. A. Cornell, and H. J. Lewandowski (in preparation)]. Given a realistic confining potential, we develop a model for studying collective modes that includes the effects of anharmonic corrections to a harmonic potential. By studying the influence of these trap anharmonicities throughout a range of temperatures and collisional regimes, we find that the damping is caused by the joint mechanisms of dephasing and collisional relaxation. Furthermore, the model is complimented by Monte Carlo simulations which are in fair agreement with data from the JILA experiment.