Speed of sound of a Bose--Einstein condensate with dipole--dipole interactions

TL;DR

This paper investigates how dipole-dipole interactions in a chromium Bose-Einstein condensate cause anisotropic properties, particularly affecting the speed of sound, and discusses potential applications in analyzing superfluid dissipation.

Contribution

It introduces a model including both contact and dipole-dipole interactions, analyzing their effects on thermodynamical properties and anisotropy in the condensate.

Findings

Dipole-dipole interactions induce anisotropy in the speed of sound.

The model predicts changes in condensate size and chemical potential due to dipolar effects.

Anisotropic properties could be used to analyze dissipative mechanisms in superfluids.

Abstract

In the present work the case of a chromium Bose-Einstein condensate is considered. The model includes not only the presence of the so-called contact interaction but also a long range and anisotropic dipole-dipole interaction has been included. Some thermodynamical properties are analyzed. For instance, the size of the condensate, chemical potential, speed of sound, number of particles, etc., are deduced. It will be shown that this dipole-dipole interaction implies the emergence of anisotropy, for example, in the speed of sound. The possible use of this anisotropy as a tool for the analyze of dissipative mechanisms, for instance, Landau's criterion for superfluidity, will be also discussed.