Many-body \textit{T}-matrix theory of a strongly interacting spin-orbit coupled Fermi gas: Momentum-resolved radio-frequency spectroscopy and fermionic pairing

TL;DR

This paper develops a strong-coupling T-matrix theoretical framework to analyze fermionic pairing in a spin-orbit coupled Fermi gas, predicting momentum-resolved spectroscopy signatures and phase diagram features near the unitary limit.

Contribution

It introduces a novel T-matrix approach for strongly interacting spin-orbit coupled Fermi gases and predicts observable spectroscopic signatures of anisotropic pairing.

Findings

Predicted a smooth transition from atomic to molecular responses in spectroscopy.

Mapped the phase diagram near the unitary resonance.

Identified clear signatures of anisotropic pairing at and below resonance.

Abstract

Interacting Fermi gases with spin-orbit coupling are responsible for many intriguing phenomena such as topological superfluids and Majorana fermions. Here we characterize theoretically fermionic pairing in a strongly interacting spin-orbit coupled Fermi gas, by using momentum-resolved radio-frequency spectroscopy. We develop a strong-coupling $T$-matrix theory and present a phase diagram near the unitary resonance limit. A smooth transition from atomic to molecular responses in the momentum-resolved spectroscopy is predicted, with a clear signature of anisotropic pairing at and below resonance. Our prediction with many-body pairing can be directly tested in a spin-orbit coupled Fermi gas of $^{40}$K or $^{6}$Li atoms near broad Feshbach resonances.