# Unusual destruction and enhancement of superfluidity of atomic Fermi gases by population imbalance in a one-dimensional optical lattice

## TL;DR

This paper investigates how population imbalance affects superfluidity in 1D optical lattice Fermi gases, revealing unusual destruction and enhancement phenomena, including a novel pair hopping mechanism and a constant critical temperature asymptote.

## Contribution

It introduces a new pair hopping mechanism assisted by majority fermions and shows superfluidity can be both suppressed and enhanced by population imbalance in 1D lattices.

## Key findings

- Superfluid phase is fragile and limited in parameter space.
- A new pair hopping mechanism leads to a constant $T_c$ asymptote.
- Superfluidity can be strongly enhanced on the BEC side with imbalance.

## Abstract

We study the superfluid behavior of a population imbalanced ultracold atomic Fermi gases with a short range attractive interaction in a one-dimensional (1D) optical lattice, using a pairing fluctuation theory. We show that, besides widespread pseudogap phenomena and intermediate temperature superfluidity, the superfluid phase is readily destroyed except in a limited region of the parameter space. We find a new mechanism for pair hopping, assisted by the excessive majority fermions, in the presence of continuum-lattice mixing, which leads to an unusual constant BEC asymptote for $T_c$ that is independent of pairing strength. In result, on the BEC side of unitarity, superfluidity, when it exists, may be strongly enhanced by population imbalance.