Fermionic superfluidity and spontaneous superflows in optical lattices

TL;DR

This paper investigates fermionic superfluidity in optical lattices, revealing a metastable paired superfluid state induced by correlated tunneling and the potential for spontaneous superflows due to lattice geometry.

Contribution

It introduces a novel mechanism for superfluidity in strongly repulsive fermions via correlated tunneling and explores spontaneous superflows in frustrated lattice geometries.

Findings

Paired superfluid state is metastable and long-lived.

Spontaneous superflows can occur in triangular lattices.

Superfluidity arises from correlated tunneling in the Hubbard model.

Abstract

We study superfluidity of strongly repulsive fermionic atoms in optical lattices. The atoms are paired up through a correlated tunneling mechanism, which induces superfluidity when repulsive nearest-neighbor interactions are included in the Hubbard model. This paired superfluid is a metastable state which persists for a long time as the pair-broken process is severely suppressed. The mean-field phase diagram and low energy excitations are investigated in a square lattice system. Intriguingly, spontaneous superflows may appear in the ground state of a triangular optical lattice system due to antiferromagnetic frustration.