Nonequilibrium dynamics of vortex arrest in a finite-temperature Bose-Einstein condensate

TL;DR

This study investigates how a rotating Bose-Einstein condensate with a vortex loses angular momentum when subjected to trap deformation at finite temperatures, revealing different decay regimes based on trap anisotropy.

Contribution

It introduces a finite-temperature dynamical simulation approach to analyze vortex arrest in Bose-Einstein condensates with varying trap anisotropies, highlighting the interplay between condensate and thermal cloud.

Findings

Strong trap anisotropy can deplete the thermal cloud's angular momentum before vortex decay.

Weak anisotropy leads to a long-lived steady state with intermediate rotation.

The relative efficiency of vortex-cloud and cloud-trap coupling depends on trap deformation.

Abstract

We perform finite-temperature dynamical simulations of the arrest of a rotating Bose-Einstein condensate by a fixed trap anisotropy, using a Hamiltonian classical-field method. We consider a quasi-two-dimensional condensate containing a single vortex in equilibrium with a rotating thermal cloud. Introducing an elliptical deformation of the trapping potential leads to the loss of angular momentum from the system. We identify the condensate and the complementary thermal component of the nonequilibrium field, and compare the evolution of their angular momenta and angular velocities. By varying the trap anisotropy we alter the relative efficiencies of the vortex-cloud and cloud-trap coupling. For strong trap anisotropies the angular momentum of the thermal cloud may be entirely depleted before the vortex begins to decay. For weak trap anisotropies, the thermal cloud exhibits a long-lived steady state in which it rotates at an intermediate angular velocity.