Neutral Vortex Necklace in a Trapped Planar Superfluid

• DOI: 10.1007/s10909-020-02547-7
• Publication Date: 2021-01-07T11:04:21Z
• Authors: M. M. Cawte; M. T. Reeves; A. S. Bradley
• Keywords: Stationary state; Metastability; Gross–Pitaevskii equation; Burgers vortex; Quantum vortex; Quantum Turbulence; Vortex state; Periodic boundary conditions; Vortex stretching

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.<br/>17 pages, 7 figures, JLTP format, comments welcome<br/>