A purely dipolar quantum gas

TL;DR

This paper experimentally investigates a Chromium Bose-Einstein condensate where long-range dipole-dipole interactions dominate, revealing unique effects on condensate shape, stability, and collapse behavior due to magnetic dipoles.

Contribution

It demonstrates control over dipolar interactions in a quantum gas and observes novel phenomena arising from anisotropic long-range forces.

Findings

Inhibition of ellipticity inversion during time-of-flight

Strong dependence of stability on trap geometry

Observation of d-wave like features during collapse

Abstract

We report on experiments exploring the physics of dipolar quantum gases using a Chromium Bose-Einstein condensate (BEC). By means of a Feshbach resonance, it is possible to reduce the effects of short range interactions and reach a regime where the physics is governed by the long-range, anisotropic dipole-dipole interaction between the large ($6 \mu_{\rm B}$) magnetic moments of Chromium atoms. Several dramatic effects of the dipolar interaction are observed: the usual inversion of ellipticity of the condensate during time-of flight is inhibited, the stability of the dipolar gas depends strongly on the trap geometry, and the explosion following the collapse of an unstable dipolar condensate displays d-wave like features.