Dynamically Slowed Collapse of a Bose-Einstein Condensate with Negative Scattering Length

TL;DR

This paper investigates the controlled collapse of a Bose-Einstein condensate with negative scattering length by rapidly tuning interactions, revealing a slowed collapse due to kinetic energy and complex behaviors explained via the Gross-Pitaevskii equation.

Contribution

It demonstrates a novel method to stabilize and analyze condensate collapse dynamics using rapid Feshbach resonance tuning and advanced modeling.

Findings

Collapse is slowed near resonance due to kinetic energy effects.

The condensate's radius increases in a way not explained by simple models.

Gross-Pitaevskii equation with three-body loss describes observed behavior.

Abstract

We rapidly change the scattering length a_s of a 87Rb Bose-Einstein condensate by means of a Feshbach resonance, simultaneously releasing the condensate from its harmonic trapping potential. When a_s is changed from positive to negative, the subsequent collapse of the condensate is stabilized by the kinetic energy imparted during the release, resulting in a deceleration of the loss rate near the resonance. We also observe an increase in the Thomas-Fermi radius, near the resonance, that cannot be understood in terms of a simple scaling model. Instead, we describe this behavior using the Gross-Pitaevskii equation, including three-body recombination, and hypothesize that the increase in cloud radius is due to the formation of concentric shells.