Dynamic response of strongly correlated Fermi gases in the quantum virial expansion

TL;DR

This paper develops a quantum virial expansion method to analyze the dynamic density response of strongly interacting Fermi gases, revealing a transition from atomic to molecular responses near unitarity, aligning with experimental observations.

Contribution

The paper introduces a quantum virial expansion approach to study dynamical properties of strongly correlated Fermi gases at high temperatures, bridging theoretical predictions with experimental data.

Findings

Identifies a transition from atomic to molecular responses in spectra.

Quantitatively matches recent Bragg spectroscopy results.

Provides a new method for strong-coupling problems in Fermi gases.

Abstract

By developing a quantum virial expansion theory, we quantitatively calculate the dynamic density response function of a trapped strongly interacting Fermi gas at high temperatures near unitarity. A clear transition from atomic to molecular responses is identified in the spectra when crossing from the BCS to BEC regimes, in qualitative agreement with recent Bragg spectroscopy observations. Our virial expansion method provides a promising way to solve the challenging strong-coupling problems and is applicable to other dynamical properties of strongly correlated Fermi gases.