Phase Fluctuations in Atomic Bose Gases

Abstract

We improve on the Popov theory for partially Bose-Einstein condensed atomic gases by treating the phase fluctuations exactly. As a result, the theory becomes valid in arbitrary dimensions and is able to describe the low-temperature crossover between three-, two-, and one-dimensional Bose gases, which is currently being explored experimentally. We consider both homogeneous and trapped Bose gases.