Decay mechanisms of superflow of Bose-Einstein condensates in ring traps

TL;DR

This paper investigates the decay mechanisms of supercurrents in Bose-Einstein condensates within ring traps, finding that thermally activated phase slips cannot explain experimental decay rates and proposing three-body losses as a more plausible cause.

Contribution

The study calculates supercurrent decay rates due to thermally activated phase slips and demonstrates their insignificance, suggesting three-body losses as a key decay mechanism.

Findings

TAPS decay rate is astronomically small compared to experimental observations.

TAPS are unlikely the primary decay mechanism in current experimental conditions.

Reducing atom number could enable observation of TAPS-induced decay.

Abstract

We study the supercurrent decay of a Bose-Einstein condensate in a ring trap combined with a repulsive barrier potential. In recent experiments, Kumar {\it et al.} [Phys. Rev. A {\bf 95}, 021602(R) (2017)] have measured the dependence of the decay rate on the temperature and the barrier strength. However, the origin of the decay observed in the experiment remains unclear. We calculate the rate of supercurrent decay due to thermally activated phase slips (TAPS) by using the Kramers formula based on the Gross-Pitaevskii mean-field theory. The resulting decay rate is astronomically small compared to that measured in the experiment, thus excluding the possibility of TAPS as the decay mechanism. Alternatively, we argue that three-body losses can be relevant to the observed decay and predict that one can observe supercurrent decay via TAPS by decreasing the number of atoms.