Trapped Bose-Bose mixtures at finite temperature: a quantum Monte Carlo approach

TL;DR

This paper investigates the thermal properties of trapped Bose-Bose mixtures using quantum Monte Carlo methods, focusing on superfluid density and condensate fraction dependence on temperature in different phases.

Contribution

It introduces a combined use of diffusion and path-integral Monte Carlo methods to analyze finite-temperature effects in Bose-Bose mixtures, comparing with Gross-Pitaevskii solutions.

Findings

Existence of anisotropic superfluid density in phase-separated mixtures

Superfluid density and condensate fraction evolve differently with temperature

Superfluid fraction can be smaller than condensate fraction in some cases

Abstract

We study thermal properties of a trapped Bose-Bose mixture in a dilute regime using quantum Monte Carlo methods. Our main aim is to investigate the dependence of the superfluid density and the condensate fraction on temperature, for the mixed and separated phases. To this end, we use the diffusion Monte Carlo method, in the zero-temperature limit, and the path-integral Monte Carlo method for finite temperatures. The results obtained are compared with solutions of the coupled Gross-Pitaevskii equations for the mixture at zero temperature. We notice the existence of an anisotropic superfluid density in some phase-separated mixtures. Our results also show that the temperature evolution of the superfluid density and condensate fraction is slightly different, showing noteworthy situations where the superfluid fraction is smaller than the condensate fraction.