Induced superfluidity of imbalanced Fermi gases near unitarity

TL;DR

This paper predicts that in strongly imbalanced Fermi gases near unitarity, induced intraspecies interactions can lead to p-wave superfluidity of the majority species, suggesting a new phase transition detectable experimentally.

Contribution

It introduces the concept that induced intraspecies interactions cause p-wave superfluidity in imbalanced Fermi gases near unitarity, expanding understanding of superfluid phases in these systems.

Findings

Induced intraspecies interactions lead to p-wave pairing.

Superfluidity of the majority species is predicted below a certain temperature.

Experimental signatures include radio-frequency spectroscopy and density correlations.

Abstract

The induced intraspecies interactions among the majority species, mediated by the minority species, is computed for a population-imbalanced two-component Fermi gas. Although the Feshbach-resonance mediated interspecies interaction is dominant for equal populations, leading to singlet s-wave pairing, we find that in the strongly imbalanced regime the induced intraspecies interaction leads to p-wave pairing and superfluidity of the majority species. Thus, we predict that the observed spin-polaron Fermi liquid state in this regime is unstable to p-wave superfluidity, in accordance with the results of Kohn and Luttinger, below a temperature that, near unitarity, we find to be within current experimental capabilities. Possible experimental signatures of the p-wave state using radio-frequency spectroscopy as well as density-density correlations after free expansion are presented.