Asymmetric Fermi superfluid in a harmonic trap

TL;DR

This paper investigates the phase separation and density profiles of an asymmetric two-component Fermi gas in a harmonic trap across different interaction regimes, revealing shell structures and mixed phases.

Contribution

It introduces a mean field and local density approximation analysis of asymmetric Fermi gases, highlighting phase separation and mixed phases across BCS, resonance, and BEC regimes.

Findings

System exhibits concentric shell structures with superfluid core and normal outer shell.

Density profiles vary systematically across interaction regimes.

In strong coupling, fermions and bosons can coexist in mixed phases.

Abstract

We consider a dilute two-component atomic fermion gas with unequal populations in a harmonic trap potential using the mean field theory and the local density approximation. We show that the system is phase separated into concentric shells with the superfluid in the core surrounded by the normal fermion gas in both the weak-coupling BCS side and near the Feshbach resonance. In the strong-coupling BEC side, the composite bosons and left-over fermions can be mixed. We calculate the cloud radii and compare axial density profiles systemically for the BCS, near resonance and BEC regimes.