We have reported on the observation of the Josephson effect between two fermionic superfluids coupled through a thin tunneling barrier. We have shown that the relative population and phase are canonically conjugate dynamical variables throughout the crossover from the molecular Bose-Einstein condensate (BEC) to the Bardeen–Cooper–Schrieffer (BCS) superfluid regime. For larger initial excitations from equilibrium, the dynamics of the superfluids become dissipative, which we ascribe to the propagation of vortices through the superfluid bulk. Our results highlight the robust nature of resonant superfluids.
Contact person: Giacomo Roati, INO–CNR Sesto Fiorentino