Finite-temperature superfluid depletion of disordered Bose gases

TL;DR

This paper develops a theoretical framework to quantify how finite temperature and disorder affect the superfluid properties of weakly interacting Bose gases, providing analytical expressions for the normal fluid density.

Contribution

It introduces an inhomogeneous Bogoliubov theory combined with diagrammatic perturbation to derive finite-temperature disorder corrections to superfluid depletion.

Findings

Derived analytical expressions for normal fluid density with disorder and temperature effects.

Extended Landau's two-fluid theory to include disorder corrections.

Applicable to Bose gases in arbitrary spatial dimensions.

Abstract

At zero temperature, homogeneous interacting Bose-condensed fluids are entirely superfluid, with remarkable transport properties. A non-superfluid, normal component is induced by finite temperatures and spatial inhomogeneity, the combined effects of which are rather intriguing, and difficult to describe quantitatively. By inhomogeneous Bogoliubov theory, applicable to weakly interacting condensed Bose gases in static external potentials with arbitrary spatial correlations, we calculate the normal fluid density via the transverse current-current correlation. We obtain finite-temperature disorder corrections to the normal fraction known since Laudau's seminal two-fluid theory, using diagrammatic perturbation theory for systems of any dimensionality, with closed analytical expressions to leading, quadratic order in disorder strength.