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Condensate fluctuations in finite Bose-Einstein condensates at finite temperature

Robert Graham
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Abstract

A Langevin equation for the complex amplitude of a single-mode Bose-Einstein condensate is derived. The equation is first formulated phenomenologically, defining three transport parameters. It is then also derived microscopically. Expressions for the transport parameters in the form of Green-Kubo formulas are thereby derived and evaluated for simple trap geometries, a cubic box with cyclic boundary conditions and an isotropic parabolic trap. The number fluctuations in the condensate, their correlation time, and the temperature-dependent collapse-time of the order parameter as well as its phase-diffusion coefficient are calculated.

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Robert Graham. 2000-05-07. Condensate fluctuations in finite Bose-Einstein condensates at finite temperature. https://doi.org/10.1103/physreva.62.023609

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