Effects of Disorder in a Dilute Bose Gas

TL;DR

This paper investigates how a weak random external potential influences the properties of a dilute Bose gas at zero temperature, including condensate depletion, superfluid density, sound velocity shifts, and phonon damping.

Contribution

It recovers previous results on condensate depletion and superfluid density and extends analysis to sound velocity shifts and phonon damping in dilute and dense superfluids.

Findings

Recovery of Huang and Meng's depletion results

Calculation of sound velocity shift and damping

Phonon damping in dense superfluids

Abstract

We discuss the effects of a weak random external potential on the properties of the dilute Bose gas at zero temperature. The results recently obtained by Huang and Meng for the depletion of the condensate and of the superfluid density are recovered. Results for the shift of the velocity of sound as well as for its damping due to collisions with the external field are presented. The damping of phonons is calculated also for dense superfluids. (submitted to Phys.Rev.B)