Dynamic formation of quasicondensate and spontaneous vortices in a strongly interacting Fermi gas

We report an experimental study of quench dynamics across the superfluid transition temperature T-c in a strongly interacting Fermi gas by ramping down the trapping potential. The nonzero quasicondensate number N-0 at temperatures significantly above T-c in the unitary and the BEC regimes is consistent with the pseudogap physics via preformed pairs. Below T-c, a rapid growth of N-0 is accompanied by the spontaneous generation of tens of vortices. We observe a power-law scaling of the vortex density versus the quasicondensate formation time, consistent with the Kibble-Zurek theory. Our work provides an example of studying emerged many-body physics by quench dynamics and paves the way for studying the quantum turbulence in a strongly interacting Fermi gas.