Hydrodynamic modes and pulse propagation in a cylindrical Bose gas above the Bose-Einstein transition

TL;DR

This paper investigates hydrodynamic oscillations and pulse propagation in a cylindrical Bose gas above the Bose-Einstein transition, comparing classical and degenerate quantum regimes using hydrodynamic equations.

Contribution

It extends previous zero-temperature studies to finite temperatures above the BEC transition, providing explicit normal mode solutions and analyzing propagating modes in the degenerate limit.

Findings

Normal modes for non-propagating solutions are explicitly obtained.

Sound velocity in the classical limit matches that of a uniform classical gas.

Propagating modes in the degenerate Bose-gas limit show little difference from classical results.

Abstract

We study hydrodynamic oscillations of a cylindrical Bose gas above the Bose-Einstein transition temperature using the hydrodynamic equations derived by Griffin, Wu and Stringari. This extends recent studies of a cylindrical Bose-condensed gas at T=0. Explicit normal mode solutions are obtained for non-propagating solutions. In the classical limit, the sound velocity is shown to be the same as a uniform classical gas. We use a variational formulation of the hydrodynamic equations to discuss the propagating modes in the degenerate Bose-gas limit and show there is little difference from the classical results.