Multiply quantized vortices and finite temperature effects in the BEC/BCS crossover regime

The interatomic interaction strength in ultracold fermionic gases can be manipulated using Feshbach resonances, allowing to probe both the regime where atoms form molecules that Bose condense (BEC) and the Bardeen-Cooper-Schrieffer (BCS) regime. We use a path-integral formalism to investigate the properties of multiply quantized vortices in these systems. Although the vortex core region expands when more quanta of circulation are present, the qualitative result is the same: in the BEC regime, the atoms do not penetrate into the vortex core, whereas in the BCS regime they do. The system undergoes a smooth crossover between the two regimes. When the temperature is increased, the penetration of atoms into the vortex core becomes more pronounced.