Neutral Vortex Necklace in a Trapped Planar Superfluid

We study quantum vortex states consisting of a ring of vortices with alternating sign, in a homogeneous superfluid confined to a circular domain. We find an exact stationary solution of the point vortex model for the neutral vortex necklace. We investigate the stability of the necklace state within both the point-vortex model and the Gross-Pitaevskii equation describing a trapped atomic Bose-Einstein condensate at low temperature. The point-vortex stationary states are found to also be stationary states of the Gross-Pitaevskii equation provided the finite thickness of the outer fluid boundary is accounted for. Under significant perturbation, the Gross-Pitaevskii evolution and point-vortex model exhibit instability as expected for metastable states. The perturbed vortex necklace exhibits sensitivity to the perturbation, suggesting a route to seeding vortex chaos or quantum turbulence.

Automated summary

In this study, quantum vortex states consisting of a ring of vortices with alternating sign in a homogeneous superfluid were investigated. An exact stationary solution for the neutral vortex necklace was found. The stability of the necklace state within both the point-vortex model and the Gross-Pitaevskii equation was examined, revealing sensitivity to perturbations and potential for vortex chaos or quantum turbulence.