Quantitative comparison between theoretical predictions and experimental results for Bragg spectroscopy of a strongly interacting Fermi superfluid

TL;DR

This paper compares theoretical predictions of the dynamic and static structure factors of a strongly interacting Fermi superfluid with experimental Bragg spectroscopy data, showing excellent agreement at low temperatures and providing temperature dependence predictions.

Contribution

It extends the random-phase approximation to the strongly interacting regime and validates it against experimental data without free parameters.

Findings

Excellent agreement between theory and experiment at low temperatures

Theoretical static structure factor matches experimental and Tan relation results

Predictions of temperature dependence of structure factors at unitarity

Abstract

Theoretical predictions for the dynamic structure factor of a harmonically trapped Fermi superfluid near the BEC-BCS crossover are compared with recent Bragg spectroscopy measurements at large transferred momenta. The calculations are based on a random-phase (or time-dependent Hartree-Fock-Gorkov) approximation generalized to the strongly interacting regime. Excellent agreement with experimental spectra at low temperatures is obtained, with no free parameters. Theoretical predictions for zero-temperature static structure factor are also found to agree well with the experimental results and independent theoretical calculations based on the exact Tan relations. The temperature dependence of the structure factors at unitarity is predicted.