Polarons in the radio-frequency spectrum of a quasi-two-dimensional Fermi gas

TL;DR

This study investigates radio-frequency spectra of a quasi-two-dimensional Fermi gas, revealing that observed resonances are better explained by polaron transitions rather than confinement-induced dimers, providing new insights into many-body physics.

Contribution

It demonstrates that in a quasi-two-dimensional Fermi gas near a Feshbach resonance, polaron states dominate the RF spectrum instead of confinement-induced dimers, offering a novel interpretation.

Findings

Resonances do not match confinement-induced dimer transitions.

Spectrum aligns with transitions between noninteracting polaron states.

Polaron physics plays a key role in RF spectra in this regime.

Abstract

We measure radio-frequency spectra for a two-component mixture of a $^6$Li atomic Fermi gas in the quasi-two-dimensional regime. Near the Feshbach resonance, where the transverse Fermi energy is large compared to the confinement-induced dimer binding energies for the initial and final states, we find that the observed resonances do not correspond to transitions between confinement-induced dimers. The spectrum appears to be well-described by transitions between noninteracting polaron states in two dimensions.