# Communal pairing in spin-imbalanced Fermi gases

## TL;DR

This paper investigates a superconducting state in spin-imbalanced Fermi gases, highlighting how correlated Cooper pairs involving minority spins can energetically favor FFLO states, supported by analytical and Monte Carlo results.

## Contribution

It introduces a new understanding of pairing correlations in spin-imbalanced Fermi gases and compares analytical and Monte Carlo methods for this state.

## Key findings

- Correlations between all fermions favor FFLO states.
- The ratio of spin populations aligns with density of states ratios.
- Analytical and Monte Carlo results agree on the state properties.

## Abstract

A spin-imbalanced Fermi gas with an attractive contact interaction forms a superconducting state whose underlying components are superpositions of Cooper pairs that share minority-spin fermions. This superconducting state includes correlations between all available fermions, making it energetically favorable to the Fulde--Ferrell--Larkin--Ovchinnikov superconducting state. The ratio of the number of up- and down-spin fermions in the instability is set by the ratio of the up- and down-spin density of states in momentum at the Fermi surfaces, to fully utilize the accessible fermions. We present analytical and complementary Diffusion Monte Carlo results for the state.