Strongly enhanced inelastic collisions in a Bose-Einstein condensate near Feshbach resonances

TL;DR

This paper reports that tuning a sodium Bose-Einstein condensate near a Feshbach resonance significantly increases inelastic three-body collision rates, posing challenges for manipulating condensate properties.

Contribution

It presents the experimental observation of strongly enhanced inelastic collisions near a Feshbach resonance, including a newly observed sodium resonance at 1195 G, and highlights limitations for condensate control.

Findings

Inelastic collision rates increase by several orders of magnitude near Feshbach resonances.

A new sodium Feshbach resonance at 1195 G was identified.

The observed loss rates are not explained by existing theories.

Abstract

The properties of Bose-Einstein condensed gases can be strongly altered by tuning the external magnetic field near a Feshbach resonance. Feshbach resonances affect elastic collisions and lead to the observed modification of the scattering length. However, as we report here, this is accompanied by a strong increase in the rate of inelastic collisions. The observed three-body loss rate in a sodium Bose-Einstein condensation increased when the scattering length was tuned to both larger or smaller values than the off-resonant value. This observation and the maximum measured increase of the loss rate by several orders of magnitude are not accounted for by theoretical treatments. The strong losses impose severe limitations for using Feshbach resonances to tune the properties of Bose-Einstein condensates. A new Feshbach resonance in sodium at 1195 G was observed.