Fermionic superfluidity and spontaneous superflows in optical lattices

摘要

We study superfluidity of strongly repulsive fermionic atoms in opticallattices. The atoms are paired up through a correlated tunneling mechanism,which induces superfluidity when repulsive nearest-neighbor interactions areincluded in the Hubbard model. This paired superfluid is a metastable statewhich persists for a long time as the pair-broken process is severelysuppressed. The mean-field phase diagram and low energy excitations areinvestigated in a square lattice system. Intriguingly, spontaneous superflowsmay appear in the ground state of a triangular optical lattice system due toantiferromagnetic frustration.