Microscopic Superfluidity in Bose Gases: From 3D to 1D

TL;DR

This paper investigates how the superfluid fraction in Bose gases varies with temperature, interaction strength, and dimensionality, revealing key differences between ideal and interacting gases across different geometries.

Contribution

It provides a detailed analysis of superfluidity in Bose gases across dimensions using path integral Monte Carlo, highlighting the independence from interaction strength and the impact of geometry.

Findings

Superfluid fraction is independent of interaction strength at finite temperatures.

Superfluid fraction varies significantly with dimensionality from 3D to 1D.

Superfluid fraction closely matches condensate fraction in spherical gases but not in elongated ones.

Abstract

The superfluid fraction of ideal and interacting inhomogeneous Bose gases with varying asymmetry is investigated at finite temperature using well-known properties of the harmonic oscillator as well as the essentially exact microscopic path integral Monte Carlo method. We find that the superfluid fraction (i) is essentially independent of the interaction strength for all temperatures considered, (ii) changes profoundly as the effective dimensionality is varied from three- to one-dimensional, (iii) is approximately equal to the condensate fraction N0/N for spherical Bose gases, and (iv) deviates dramatically from N0/N for highly-elongated Bose gases.