Determination of the Superfluid Gap in Atomic Fermi Gases by Quasiparticle Spectroscopy

TL;DR

This paper uses RF spectroscopy to measure the superfluid gap and Hartree energy in imbalanced Li-6 Fermi gases, revealing the evolution from pairing to polaron binding and quasiparticle effects.

Contribution

It introduces a method to determine the superfluid gap and Hartree energy in imbalanced Fermi gases through quasiparticle spectroscopy.

Findings

Observation of a smooth transition from pairing to polaron binding

Detection of quasiparticles at low temperature in the superfluid

Measurement of superfluid gap nd Hartree energy U

Abstract

We present majority and minority radiofrequency (RF) spectra of strongly interacting imbalanced Fermi gases of Li-6. We observed a smooth evolution in the nature of pairing correlations from pairing in the superfluid region to polaron binding in the highly polarized normal region. The imbalance induces quasiparticles in the superfluid region even at very low temperature. This leads to a local bimodal spectral response, which allows us to determine the superfluid gap \Delta and the Hartree energy U.