Universal contact and collective excitations of a strongly interacting Fermi gas

TL;DR

This paper investigates how Tan's contact parameter relates to collective excitations and sound propagation in strongly interacting ultracold Fermi gases, demonstrating accurate predictions of experimental measurements.

Contribution

It establishes a connection between Tan's contact and macroscopic dynamic properties, providing a theoretical framework that matches experimental data near unitarity.

Findings

Tan's contact accurately predicts collective mode frequencies.

The contact explains sound velocity measurements in 1D gases.

Theoretical results align with recent low-temperature experiments.

Abstract

We study the relationship between Tan's contact parameter and the macroscopic dynamic properties of an ultracold trapped gas, such as the frequencies of the collective oscillations and the propagation of sound in one-dimensional (1D) configurations. We find that the value of the contact, extracted from the most recent low-temperature measurements of the equation of state near unitarity, reproduces with accuracy the experimental values of the collective frequencies of the radial breathing mode at the lowest temperatures. The available experiment results for the 1D sound velocities near unitarity are also investigated.