Probing the homogeneous spectral function of a strongly interacting superfluid atomic Fermi gas in a trap using phase separation and momentum resolved rf spectroscopy

TL;DR

This paper proposes a method to extract the local spectral function of a homogeneous superfluid Fermi gas from phase-separated, population imbalanced systems using momentum resolved rf spectroscopy, overcoming trap inhomogeneity limitations.

Contribution

It introduces a novel approach to probe the local spectral function of a homogeneous superfluid Fermi gas via phase separation and rf spectroscopy, supported by theoretical calculations.

Findings

Spectral functions calculated across BCS to BEC regimes.

Spectral intensity maps demonstrate the method's effectiveness.

Supports extraction of homogeneous spectral properties from inhomogeneous traps.

Abstract

It is of central importance to probe the \emph{local} spectral function $A(\mathbf{k},\omega)$ of a strongly interacting Fermi gas in a trap. Momentum resolved rf spectroscopy has been demonstrated to be able to probe the trap averaged $A(\mathbf{k},\omega)$. However, the usefulness of this technique was limited by the trap inhomogeneity. Independent of a specific theory, here we propose that by studying the momentum resolved rf spectra of the minority fermions of a phase separated, population imbalanced Fermi gas at low temperature, one can effectively extract $A(\mathbf{k},\omega)$ of a homogeneous superfluid Fermi gas (at the trap center). In support, we present calculated spectral functions and spectral intensity maps for various cases from BCS through BEC regimes using different theories.