Vortex Lattice Locking in Rotating Two-Component Bose-Einstein Condensates

TL;DR

This paper explores how vortex lattices in rotating two-component Bose-Einstein condensates lock together under strong interspecies attraction, revealing a state where vortices synchronize with the drive frequency while superfluids rotate at different velocities.

Contribution

It introduces the vortex-locked state in two-component BECs, characterizes its stability, and explains the conditions under which vortices lock and unbind in such systems.

Findings

Vortex lattices lock and rotate at the drive frequency under strong attraction.

Superfluids rotate at velocities proportional to their particle masses.

Vortex locking persists within a critical radius, beyond which vortices unbind.

Abstract

The vortex density of a rotating superfluid, divided by its particle mass, dictates the superfluid's angular velocity through the Feynman relation. To find how the Feynman relation applies to superfluid mixtures, we investigate a rotating two-component Bose-Einstein condensate, composed of bosons with different masses. We find that in the case of sufficiently strong interspecies attraction, the vortex lattices of the two condensates lock and rotate at the drive frequency, while the superfluids themselves rotate at two different velocities, whose ratio is the ratio between the particle mass of the two species. In this paper, we characterize the vortex-locked state, establish its regime of stability, and find that it surives within a disk smaller than a critical radius, beyond which vortices become unbound, and the two Bose-gas rings rotate together at the frequency of the external drive.