Observation of self-patterned defect formation in atomic superfluids - from ring dark solitons to vortex dipole necklaces
Authors: Hikaru Tamura, Cheng-An Chen, Chen-Lung Hung
Journal Ref: arXiv:2211.08575
Unveiling non-equilibrium dynamics of solitonic and topological defect structures in a multidimensional nonlinear medium is a current frontier across diverse fields. One of the quintessential objects is a ring dark soliton (RDS), whose dynamics are expected to display remarkable interplay between symmetry and self-patterned topological defect formation from a transverse (snake) instability but has thus far evaded full experimental observations. Here, we report an experimental realization of RDS generation in a two-dimensional atomic superfluid trapped in a circular box. By quenching the confining box potential, we observe spontaneous soliton emission from the edge and its signature radial collapse dynamics in a superfluid. As an RDS evolves, we observe spontaneous transverse modulations at discrete azimuthal angles, which clearly result in a patterned formation of a circular vortex dipole array. Through collisions of the vortex dipoles with the box trap, we observe vortex unbinding, vortex pinning to the edge, and emission of rarefaction pulses. Our box-quench protocol opens a new way to study multidimensional dark solitons, structured formation of topological defects, and potentially the dynamics of ordered quantum vortex matter.