Bose-Einstein condensate fluctuations versus an interparticle interaction
Abstract
We calculate the Bose-Einstein condensate (BEC) occupation statistics vs. the interparticle interaction in a dilute gas with a nonuniform condensate in a box trap within the Bogoliubov approach. The results are compared against the previously found BEC-occupation statistics in (i) an ideal gas and (ii) a weakly interacting gas with a uniform condensate. In particular, we reveal and explicitly describe an appearance of a nontrivial transition from the ideal gas to the Thomas-Fermi regime. The results include finding the main regimes of the BEC statistics - the anomalous non-Gaussian thermally-dominated fluctuations and the Gaussian quantum-dominated fluctuations - as well as a crossover between them and their manifestations in a mesoscopic system. Remarkably, we show that the effect of the boundary conditions, imposed at the box trap, on the BEC fluctuations does not vanish in the thermodynamic limit of a macroscopic system even in the presence of the interparticle interactions. Finally, we discuss a challenging problem of an experimental verification of the theory of the BEC fluctuations addressing a much deeper level of the many-body statistical physics than usually studied quantities related to the mean condensate occupation.
Cite
@article{arxiv.2007.15753,
title = {Bose-Einstein condensate fluctuations versus an interparticle interaction},
author = {Sergey V. Tarasov and Vladimir V. Kocharovsky and Vitaly V. Kocharovsky},
journal= {arXiv preprint arXiv:2007.15753},
year = {2021}
}
Comments
This is a replacement of the first arXiv version (from July 30th, 2020) with misprints corrected