Grand-canonical condensate fluctuations in weakly interacting Bose-Einstein condensates of light

Weiss, C.; Tempere, J.

Abstract

Grand-canonical fluctuations of Bose-Einstein condensates of light are accessible to state-of-the-art experiments [J. Schmitt et al., Phys. Rev. Lett. 112, 030401 (2014).]. We phenomenologically describe these fluctuations by using the grand-canonical ensemble for a weakly interacting Bose gas at thermal equilibrium. For a two-dimensional harmonic trap, we use two models for which the canonical partition functions of the weakly interacting Bose gas are given by exact recurrence relations. We find that the grand-canonical condensate fluctuations for weakly interacting Bose gases vanish at zero temperature, thus behaving qualitatively similarly to an ideal gas in the canonical ensemble (or microcanonical ensemble) rather than the grand-canonical ensemble. For low but finite temperatures, the fluctuations remain considerably higher than for the canonical ensemble, as predicted by the ideal gas in the grand-canonical ensemble, thus clearly showing that we are not in a regime in which the ensembles are equivalent.

Citation

Weiss, C., & Tempere, J. (2016). Grand-canonical condensate fluctuations in weakly interacting Bose-Einstein condensates of light. Physical Review E, 94(4), Article 042124. https://doi.org/10.1103/physreve.94.042124

• Journal Article Type: Article
• Acceptance Date: Oct 19, 2016
• Online Publication Date: Oct 19, 2016
• Publication Date: Oct 19, 2016
• Deposit Date: Oct 7, 2016
• Publicly Available Date: Oct 24, 2016
• Journal: Physical review . E, Statistical, nonlinear, and soft matter physics
• Print ISSN: 2470-0045
• Electronic ISSN: 2470-0053
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 94
• Issue: 4
• Article Number: 042124
• DOI: https://doi.org/10.1103/physreve.94.042124
• Public URL: https://durham-repository.worktribe.com/output/1403240
• Related Public URLs: https://arxiv.org/abs/1511.03064