Helicity transfer during quantised vortex reconnection

TL;DR

This paper investigates how helicity is transferred during the reconnection of quantised vortex rings in a Bose-Einstein condensate, revealing implications for quantum turbulence and connections to classical fluid dynamics.

Contribution

It demonstrates that vortex reconnection can transfer helicity to vortex twisting, linking quantum vortex dynamics to classical and magnetised fluid reconnections.

Findings

Helicity transfer occurs during vortex reconnection.

Twisting of vortex phase leads to axial flow.

Initial helicity influences quantum turbulence dynamics.

Abstract

We consider the reconnection of two untwisted, linked quantised vortex rings in a Bose-Einstein condensate. We show that the reconnection is capable of transferring helicity, from the links present in the initial configuration, to a twisting of the resulting vortex ring, and hence a rotation of the phase plane along the vortex ring. As velocities in a quantum fluid are the gradient of the phase, a twisting of the phase along the vortices leads to an axial flow along the vortices. Hence one would expect that the dynamics of quantum turbulence are strongly influence by the helicity of the initial conditions or the system forcing. Our results also provide an important link between quantised vortex reconnections and reconnections in classical and magnetised fluids.