Dynamics of a trapped ultracold two-dimensional atomic gas

TL;DR

This paper investigates the equilibrium, collective oscillations, expansion dynamics, and collisional effects of a trapped two-dimensional ultracold Bose gas, highlighting the transition between hydrodynamic and collisionless regimes.

Contribution

It provides a comprehensive analysis of the dynamical properties and collisional behavior of 2D Bose gases, including relaxation times and the crossover between different dynamical regimes.

Findings

Derived frequencies and damping rates of collective oscillations.

Analyzed the expansion dynamics after trap release.

Established the relationship between collision rate and relaxation time.

Abstract

This article is devoted to the study of two-dimensional Bose gases harmonically confined. We first summarize their equilibrium properties. For such a gas above the critical temperature, we also derive the frequencies and the damping of the collective oscillations and we investigate its expansion after releasing of the trap. The method is well suited to study the collisional effects taking place in the system and in particular to discuss the crossover between the hydrodynamic and the collisionless regimes. We establish the link between the relaxation times relevant for the damping of the collective oscillations and for the time-of-flight expansion. We also evaluate the collision rate and its relationship with the relaxation time.