Tomographic RF Spectroscopy of a Trapped Fermi Gas at Unitarity

TL;DR

This paper reports on spatially resolved radio-frequency spectroscopy of a trapped Fermi gas at unitarity, revealing a spectral gap and asymmetric excitation line shape at low temperatures, advancing understanding of strongly interacting Fermi systems.

Contribution

It introduces a method for spatially resolving RF spectra in a trapped Fermi gas at unitarity, providing detailed insights into its spectral properties.

Findings

Observation of a spectral gap at low temperatures

Asymmetric excitation line shape with a peak at 0.48(4)$psilon_F$

Spatial distribution of spectral response obtained via in situ imaging

Abstract

We present spatially resolved radio-frequency spectroscopy of a trapped Fermi gas with resonant interactions and observe a spectral gap at low temperatures. The spatial distribution of the spectral response of the trapped gas is obtained using in situ phase-contrast imaging and 3D image reconstruction. At the lowest temperature, the homogeneous rf spectrum shows an asymmetric excitation line shape with a peak at 0.48(4)$\epsilon_F$ with respect to the free atomic line, where $\epsilon_F$ is the local Fermi energy.