Radio frequency spectroscopy and the pairing gap in trapped Fermi gases

TL;DR

This paper offers a theoretical analysis of RF spectroscopy in trapped Fermi gases, explaining spectral features across the BCS-BEC crossover and matching experimental observations.

Contribution

It provides a comprehensive theoretical interpretation of RF pairing gap experiments, including the physical origin of spectral peaks, across the entire crossover.

Findings

RF spectra agree semi-quantitatively with experiments

Identifies two distinct spectral peaks and their physical origins

Analyzes pairing phenomena above and below critical temperature T_c

Abstract

We present a theoretical interpretation of radio-frequency (RF) pairing gap experiments in trapped atomic Fermi gases, over the entire range of the BCS-BEC crossover, for temperatures above and below $T_c$. Our calculated RF excitation spectra, as well as the density profiles on which they are based, are in semi-quantitative agreement with experiment. We provide a detailed analysis of the physical origin of the two different peak features seen in RF spectra, one associated with nearly free atoms at the edge of the trap, and the other with (quasi-)bound fermion pairs.