Number-of-particle fluctuations in systems with Bose-Einstein condensate

TL;DR

This paper investigates particle number fluctuations in Bose-Einstein condensates, demonstrating that within Bogolubov theory, these fluctuations are normal in both canonical and grand canonical ensembles.

Contribution

It shows that particle number fluctuations are normal in dilute interacting Bose gases within Bogolubov theory, contrasting with previous assumptions of anomalous fluctuations.

Findings

Fluctuations are normal in Bogolubov theory.

Fluctuations are normal in both ensembles.

Condensed and noncondensed particles exhibit normal fluctuations.

Abstract

Fluctuations of the number of particles for the dilute interacting gas with Bose-Einstein condensate are considered. It is shown that in the Bogolubov theory these fluctuations are normal. The fluctuations of condensed as well as noncondensed particles are also normal both in canonical and grand canonical ensembles.