Exotic superfluidity in cold atoms

TL;DR

This paper derives an effective theory for asymmetric fermionic superfluids, revealing a stable gapless phase with unique vortex properties, and maps its phase diagram based on chemical potentials.

Contribution

It introduces a low energy effective action for collective modes in asymmetric fermionic systems, highlighting the existence of a stable gapless superfluid phase and its experimental signatures.

Findings

Identification of a stable gapless superfluid phase with one Fermi surface

Prediction of increased vortex core size in the gapless phase

Phase diagram mapped in terms of chemical potentials

Abstract

We derived the low energy effective action for the collective modes in asymmetric fermionic systems with attractive interaction. We obtained the phase diagram in terms of the chemical potentials. It features a stable gapless superfluidity with one Fermi surface on the BEC side of the resonance. Also we predict a sharp increase in outer core of a vortex, i.e. vortex size, upon entering into the gapless phase. This may serve as a signature of a gapless phase.