Radio frequency spectrum of fermions near a narrow Feshbach resonance

TL;DR

This paper models the RF spectrum of fermionic atoms near a narrow Feshbach resonance, revealing two peaks with temperature-dependent features, and provides both microscopic and model-independent insights.

Contribution

It introduces a two-channel resonance model to analyze RF spectra near narrow Feshbach resonances, highlighting the spectral features and their temperature dependence.

Findings

RF spectrum contains two peaks with one dominating in wide-resonance limit

Strong temperature dependence linked to energy-dependent scattering

Sum rule analysis reveals generic, model-independent spectral features

Abstract

We calculate the radio frequency (RF) spectrum of fermionic atoms near a narrow Feshbach resonance, explaining observations made in ultracold samples of $^6\rm{Li}$ [E. L. Hazlett {\it et al.}, Phys. Rev. Lett. {\bf 108}, 045304 (2012)]. We use a two channel resonance model to show that the RF spectrum contains two peaks. In the wide-resonance limit, nearly all spectral weight lies in one of these peaks, and typically the second peak is very broad. We find strong temperature dependence, which can be traced to the energy dependence of the two-particle scattering. In addition to microscopic calculations, we use sum rule arguments to find generic features of the spectrum which are model independent.