Anomalous condensate fluctuations in strongly interacting superfluids

TL;DR

This paper demonstrates that superfluid Bose liquids exhibit unusually large condensate fluctuations at finite temperatures, with specific scaling behaviors in three and two dimensions, revealing new insights into their fluctuation properties.

Contribution

It generalizes known fluctuation results from weakly interacting gases to strongly interacting superfluids, highlighting anomalous fluctuation scaling in different dimensions.

Findings

Variance scales as T^2 V^{4/3} in 3D at low T

Fluctuations are comparable to the mean in 2D quasicondensates

Large fluctuations are a general feature of superfluid Bose liquids

Abstract

We show that the condensate occupation of a superfluid Bose liquid quite generally exhibits anomalously large fluctuations at finite temperatures. In three dimensions, the variance scales like T^2 V^{4/3} at low T, generalizing the result obtained by Giorgini, Pitaevskii, and Stringari for a weakly interacting Bose gas. In two dimensions there is only a quasicondensate, and the fluctuations are of the same order as the mean value.