Vortex dynamics in trapped Bose-Einstein condensate

TL;DR

This paper uses numerical simulations to study vortex behavior in trapped Bose-Einstein condensates, revealing how vortices precess, emit sound, and vanish at finite temperatures, and relating damping to vortex-normal fluid interactions.

Contribution

It introduces a phenomenological model for vortex dynamics at finite temperatures and connects damping parameters to superfluid helium friction coefficients.

Findings

Vortices precess and emit acoustic waves at zero temperature.

Vortices move to the condensate edge and disappear at finite temperature.

Damping parameters are related to vortex-normal fluid friction coefficients.

Abstract

We perform numerical simulations of vortex motion in a trapped Bose-Einstein condensate by solving the two-dimensional Gross-Pitaevskii Equation in the presence of a simple phenomenological model of interaction between the condensate and the finite temperature thermal cloud. At zero temperature, the trajectories of a single, off - centred vortex precessing in the condensate, and of a vortex - antivortex pair orbiting within the trap, excite acoustic emission. At finite temperatures the vortices move to the edge of the condensate and vanish. By fitting the finite -temperature trajectories, we relate the phenomenological damping parameter to the friction coefficients $\alpha$ and $\alpha^{'}$, which are used to describe the interaction between quantised vortices and the normal fluid in superfluid helium.