Theory of RF-spectroscopy of strongly interacting Fermions

TL;DR

This paper presents a theoretical analysis of RF-spectroscopy in strongly interacting Fermi gases, revealing a gap-like feature due to pairing correlations and explaining experimental observations.

Contribution

It introduces a theoretical framework for RF-spectroscopy in strongly interacting Fermi gases, including the effects of pairing and imbalance.

Findings

RF-spectrum shows a gap-like structure due to pairing correlations

RF-shift proportional to Fermi velocity and scattering length

Spectrum measures binding energy in imbalanced gases

Abstract

We show that strong pairing correlations in Fermi gases lead to the appearance of a gap-like structure in the RF-spectrum, both in the balanced superfluid and in the normal phase above the Clogston-Chandrasekhar limit. The average RF-shift of a unitary gas is proportional to the ratio of the Fermi velocity and the scattering length with the final state. In the strongly imbalanced case, the RF-spectrum measures the binding energy of a minority atom to the Fermi sea of majority atoms. Our results provide a qualitative understanding of recent experiments by Schunck et.al.