Quantised supercurrent decay in an annular Bose-Einstein condensate

TL;DR

This study investigates the decay dynamics of multiply-charged supercurrents in a ring-shaped Bose-Einstein condensate, revealing quantized decay steps and stochastic phase slips with high detection fidelity.

Contribution

It demonstrates optical phase-imprinting of high-charge superflows, resolves quantized decay steps, and provides detailed analysis of phase-slip dynamics in BECs.

Findings

Supercurrent with charge up to q=10 can be imprinted and detected.

Decay occurs via quantized steps associated with vortex-induced phase slips.

Supercurrent decay rate depends on superflow speed relative to a critical velocity.

Abstract

We study the metastability and decay of multiply-charged superflow in a ring-shaped atomic Bose-Einstein condensate. Supercurrent corresponding to a giant vortex with topological charge up to q=10 is phase-imprinted optically and detected both interferometrically and kinematically. We observe q=3 superflow persisting for up to a minute and clearly resolve a cascade of quantised steps in its decay. These stochastic decay events, associated with vortex-induced $2 \pi$ phase slips, correspond to collective jumps of atoms between discrete q values. We demonstrate the ability to detect quantised rotational states with > 99 % fidelity, which allows a detailed quantitative study of time-resolved phase-slip dynamics. We find that the supercurrent decays rapidly if the superflow speed exceeds a critical velocity in good agreement with numerical simulations, and we also observe rare stochastic phase slips for superflow speeds below the critical velocity.