Damping of Condensate Oscillation of a Trapped Bose Gas in a One-Dimensional Optical Lattice at Finite Temperatures

TL;DR

This paper investigates how finite temperature and lattice depth affect the damping of dipole oscillations in a trapped Bose gas, using a quasi-1D model that incorporates radial thermal excitations, and finds results consistent with experiments.

Contribution

It introduces a quasi-1D model including radial thermal excitations to analyze damping in Bose gases at finite temperatures, aligning theoretical predictions with experimental data.

Findings

Damping rate increases with lattice depth.

Damping rate shows strong temperature dependence.

Radial thermal excitations significantly influence damping.

Abstract

We study damping of a dipole oscillation in a Bose-Condensed gas in a combined cigar-shaped harmonic trap and one-dimensional (1D) optical lattice potential at finite temperatures. In order to include the effect of thermal excitations in the radial direction, we derive a quasi-1D model of the Gross-Pitaeavskii equation and the Bogoliubov equations. We use the Popov approximation to calculate the temperature dependence of the condensate fraction with varying lattice depth. We then calculate the Landau damping rate of a dipole oscillation as a function of the lattice depth and temperature. The damping rate increases with increasing lattice depth, which is consistent with experimental observations. The magnitude of the damping rate is in reasonable agreement with experimental data. We also find that the damping rate has a strong temperature dependence, showing a sharp increase with increasing temperature. Finally, we emphasize the importance of the radial thermal excitations in both equilibrium properties and the Landau damping.