Interactions of vortices with rarefaction solitary waves in a Bose-Einstein condensate and their role in the decay of superfluid turbulence

TL;DR

This paper investigates how rarefaction solitary waves interact with vortices in Bose-Einstein condensates, revealing their dual role in vortex creation and decay, and their impact on superfluid turbulence dissipation.

Contribution

It provides a detailed analysis of the interactions between rarefaction waves and vortices, highlighting their significance in superfluid turbulence decay within the Gross-Pitaevskii framework.

Findings

Rarefaction waves can generate vortex lines by acquiring circulation.

Kelvin waves on vortices lead to sound emission and vortex decay.

Interactions with rarefaction pulses accelerate superfluid turbulence decay.

Abstract

There are several ways to create the vorticity-free solitary waves -- rarefaction pulses -- in condensates: by the process of strongly nonequilibrium condensate formation in a weakly interacting Bose gas, by creating local depletion of the condensate density by a laser beam, and by moving a small object with supercritical velocities. Perturbations created by such waves colliding with vortices are studied in the context of the Gross-Pitaevskii model. We find that the effect of the interactions consists of two competing mechanisms: the creation of vortex line as rarefaction waves acquire circulation in a vicinity of a vortex core and the loss of the vortex line to sound due to Kelvin waves that are generated on vortex lines by rarefaction pulses. When a vortex ring collides with a rarefaction wave, the ring either stabilises to a smaller ring after emitting sound through Kelvin wave radiation or the entire energy of the vortex ring is lost to sound if the radius of the ring is of the order of the healing length. We show that during the time evolution of a tangle of vortices, the interactions with rarefaction pulses provide an important dissipation mechanism enhancing the decay of superfluid turbulence.