Spontaneous Persistent Current Formation in a Fermionic Superfluid Ring

The Kibble-Zurek mechanism (KZM) is a paradigmatic prediction of universal critical dynamics as a system is quenched across a continuous phase transition. In narrow annular geometries, quench-induced coarsening gives rise todefects which merge to form spontaneous supercurrents, whose winding numbers are predicted to scale universally with the quench time via the KZM. We report on the statistics of spontaneous persistent current formation in a ring of superfluid 6Li driven across its critical point. Namely, we measure scalings of post-quench winding number cumulants over several orders of magnitude of quench times, and with varying amounts of initial angular momentum bias imparted to the normal fluid above the transition. We compare our findings with novel analytic predictions obtained from a linearized stochastic time-dependent Landau-Ginzburg model.