Zain Mehdi, Ashton S. Bradley, Joseph J. Hope, Stuart S. Szigeti
SciPost Phys. 11, 080 (2021) ·
published 21 October 2021
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We theoretically investigate the stochastic decay of persistent currents in a
toroidal ultracold atomic superfluid caused by a perturbing barrier.
Specifically, we perform detailed three-dimensional simulations to model the
experiment of Kumar et al. in [Phys. Rev. A 95 021602 (2017)], which observed a
strong temperature dependence in the timescale of superflow decay in an
ultracold Bose gas. Our ab initio numerical approach exploits a classical-field
framework that includes thermal fluctuations due to interactions between the
superfluid and a thermal cloud, as well as the intrinsic quantum fluctuations
of the Bose gas. In the low-temperature regime our simulations provide a
quantitative description of the experimental decay timescales, improving on
previous numerical and analytical approaches. At higher temperatures, our
simulations give decay timescales that range over the same orders of magnitude
observed in the experiment, however, there are some quantitative discrepancies
that are not captured by any of the mechanisms we explore. Our results suggest
a need for further experimental and theoretical studies into superflow
stability.
