Metastable superfluidity of repulsive fermionic atoms in optical lattices

TL;DR

This paper demonstrates that in the large-U Hubbard model, metastable superfluid states can be prepared using the long-lived doubly occupied states of fermionic atoms in optical lattices, with stability influenced by pair interactions.

Contribution

It introduces a method to create metastable superfluidity in repulsive fermionic systems by exploiting the long lifetime of doubly occupied states, supported by a mapping to the ferromagnetic Heisenberg model.

Findings

Doubly occupied states Bose condense during expansion from a band insulator.

Nearest-neighbor repulsion and pair hopping stabilize superfluidity.

Metastable superfluid states can be reliably prepared in large-U Hubbard systems.

Abstract

In the fermionic Hubbard model, doubly occupied states have an exponentially large lifetime for strong repulsive interactions U. We show that this property can be used to prepare a metastable s-wave superfluid state for fermionic atoms in optical lattices described by a large-U Hubbard model. When an initial band-insulating state is expanded, the doubly occupied sites Bose condense. A mapping to the ferromagnetic Heisenberg model in an external field allows for a reliable solution of the problem. Nearest-neighbor repulsion and pair hopping are important in stabilizing superfluidity.