Molecular signatures in the structure factor of an interacting Fermi gas

TL;DR

This paper investigates the structure factors of an interacting Fermi gas across the BCS-BEC crossover, revealing molecular excitations and correlation effects through quantum Monte Carlo and mean-field methods.

Contribution

It provides new insights into the structure factors and molecular excitations in an interacting Fermi gas, especially near the BEC side of the crossover.

Findings

Spin structure factor is highly sensitive to molecular correlations.

Evidence of molecular excitation at ^2 k^2 / 4m near unitarity.

Quantum Monte Carlo and mean-field results agree on key features.

Abstract

The static and dynamic structure factors of an interacting Fermi gas along the BCS-BEC crossover are calculated at momentum transfer $\hbar{\bf k}$ higher than the Fermi momentum. The spin structure factor is found to be very sensitive to the correlations associated with the formation of molecules. On the BEC side of the crossover, even close to unitarity, clear evidence is found for a molecular excitation at $\hbar^2 k^2 /4m$, where $m$ is the atomic mass. Both quantum Monte Carlo and dynamic mean-field results are presented.