Stabilizing a purely dipolar quantum gas against collapse

TL;DR

This paper experimentally demonstrates the collapse of a dipolar quantum gas when contact interactions are reduced, and shows how trap geometry and dipole orientation influence stability, enabling stabilization of a purely dipolar gas.

Contribution

It provides the first experimental observation of dipolar collapse and explores stability conditions, including stabilization of a purely dipolar quantum gas using trap geometry.

Findings

Collapse occurs when contact interactions are minimized.

Stability depends on trap geometry and dipole orientation.

Purely dipolar gas stabilized in a pancake-shaped trap.

Abstract

We report on the experimental observation of the dipolar collapse of a quantum gas which sets in when we reduce the contact interaction below some critical value using a Feshbach resonance. Due to the anisotropy of the dipole-dipole interaction, the stability of a dipolar Bose-Einstein condensate depends not only on the strength of the contact interaction, but also on the trapping geometry. We investigate the stability diagram and find good agreement with a universal stability threshold arising from a simple theoretical model. Using a pancake-shaped trap with the dipoles oriented along the short axis of the trap, we are able to tune the scattering length to zero, stabilizing a purely dipolar quantum gas.