Temperature-Dependent Decay of Quasi-Two-Dimensional Vortices across the BCS-BEC Crossover

We systematically study the decay of quasi-two-dimensional vortices in an oblate strongly interacting Fermi gas over a wide interaction range and observe that, as the system temperature is lowered, the vortex lifetime increases in the Bose-Einstein condensate (BEC) regime but decreases at unitarity and in the Bardeen-Cooper-Schrieffer (BCS) regime. The observations can be qualitatively captured by a phenom-enological model simply involving diffusion and two-body collisional loss, in which the vortex lifetime is mostly determined by the slower process of the two. In particular, the counterintuitive vortex decay in the BCS regime can be interpreted by considering the competition between the temperature dependence of the vortex annihilation rate and that of unpaired fermions. Our results suggest a competing mechanism for the complex vortex decay dynamics in the BCS-BEC crossover for the fermionic superfluids.

Automated summary

We systematically studied the decay of quasi-two-dimensional vortices in an oblate strongly interacting Fermi gas. We observed that as the system temperature decreases, the lifetime of the vortices increases in the BEC regime but decreases at unitarity and in the BCS regime. These observations can be qualitatively explained by a phenomenological model involving diffusion and two-body collisional loss, where the vortex lifetime is mainly determined by the slower process. The counterintuitive vortex decay in the BCS regime can be interpreted by considering the competition between the temperature dependence of the vortex annihilation rate and that of unpaired fermions. Our findings suggest a competing mechanism for the complex vortex decay dynamics in the BCS-BEC crossover for fermionic superfluids.