Trapped Bose-Einstein condensates at finite temperature: a two-gas model

TL;DR

This paper presents a simple two-gas model for dilute trapped Bose gases at finite temperature, showing the condensate wavefunction remains similar to zero-temperature cases and describing the non-condensed atoms via ideal Bose gas statistics.

Contribution

It introduces a straightforward physical model for partially-condensed Bose gases at finite temperature, connecting the condensate and non-condensed components within the Hartree-Fock-Bogoliubov-Popov framework.

Findings

Condensate wavefunction remains nearly unchanged at finite temperature.

Non-condensed atoms can be modeled as an ideal Bose gas in combined potentials.

The model has implications for designing future experiments.

Abstract

A simple picture describes the results of recent treatments of partially-condensed, dilute, trapped Bose gases at temperature T > 0. The condensate wavefunction is nearly identical to that of a T=0 condensate with the same number of condensate atoms, N_0. The cloud of non-condensed atoms is described by the statistical mechanics of an ideal Bose gas in the combined potentials of the magnetic trap and the cloud-condensate interaction. We provide a physical motivation for this result, show how it emerges in the Hartree-Fock-Bogoliubov-Popov approximation, and explore some of its implications for future experiments.