Damping of low-energy excitations of a trapped Bose condensate at finite temperatures

TL;DR

This paper develops a theoretical framework for understanding how low-energy excitations in a trapped Bose condensate lose energy at finite temperatures, highlighting the role of thermal interactions and trap geometry.

Contribution

The paper introduces a novel theory accounting for damping mechanisms in trapped Bose condensates, emphasizing the importance of stochastic behavior of thermal excitations and boundary effects.

Findings

Damping rates align with recent experimental data from JILA and MIT.

Damping is significantly influenced by the condensate boundary region.

Damping behavior differs markedly from that in homogeneous gases.

Abstract

We present the theory of damping of low-energy excitations of a trapped Bose condensate at finite temperatures, where the damping is provided by the interaction of these excitations with the thermal excitations. We emphasize the key role of stochastization in the behavior of the thermal excitations for damping in non-spherical traps. The damping rates of the lowest excitations, following from our theory, are in fair agreement with the data of recent JILA and MIT experiments. The damping of quasiclassical excitations is determined by the condensate boundary region, and the result for the damping rate is drastically different from that in a spatially homogeneous gas.