Dynamics of elliptical vortices in a trapped quantum fluid

TL;DR

This paper investigates how elliptical vortices in trapped quantum fluids move and precess, revealing that their trajectories reflect their ellipticity and precession rate, which can be observed and used for control.

Contribution

It provides an analytical and numerical framework linking vortex ellipticity and precession to observable trajectories in quantum fluids.

Findings

Vortices follow elliptic trajectories matching their shape in a trap.

Nonlinear interactions cause vortex precession.

Trajectory observation allows inference of vortex ellipticity and precession rate.

Abstract

The nonequilibrium dynamics of vortices in 2D quantum fluids can be predicted by accounting for the way in which vortex ellipticity is coupled to the gradient in background fluid density. In the absence of nonlinear interactions, a harmonically trapped fluid can be analyzed analytically to show that single vortices will move in an elliptic trajectory that has the same orientation and aspect ratio as the vortex projection itself. This allows the vortex ellipticity to be estimated through observation of its trajectory. A combination of analysis and numerical simulation is then used to show that nonlinear interactions cause the vortex orientation to precess, and that the rate of vortex precession is once again mimicked by a precession of the elliptical trajectory. Both vortex ellipticity and rate of precession can therefore be inferred by observing its motion in a trap. An ability to anticipate and control local vortex structure and vortex trajectory is expected to prove useful in designing few-vortex systems in which ellipticity is a ubiquitous, as-yet-unharnessed feature.