Universal thermodynamics of strongly interacting Fermi gases

TL;DR

This paper tests the universal thermodynamic behavior of strongly interacting Fermi gases using experimental data from ultra-cold atom experiments and finds excellent agreement with theoretical predictions, supporting the universality hypothesis.

Contribution

It provides the first detailed experimental validation of the universal thermodynamic behavior of strongly interacting Fermi gases across different atomic species and trap environments.

Findings

Excellent agreement between experiment and theory without adjustable parameters.

Determination of the many-body parameter β ≈ -0.59 ± 0.07.

Supports the universality of strongly interacting Fermi gases.

Abstract

Strongly interacting Fermi gases are of great current interest. Not only are fermions the most common particles in the universe, but they are also thought to have a universal thermodynamic behavior for strong interactions \cite{heiselberg,carlson,ho}. Recent experiments on ultra-cold Fermi gases provide an unprecedented opportunity to test universality in the laboratory \cite{hara,thomas,partridge,stewart,luo}. In principle this allows - for example - the interior properties of hot, dense neutron stars to be investigated on earth. Here we carry out a detailed test of this prediction. We analyze results from three ultra-cold fermion experiments involving two completely distinct atomic species in different kinds of atomic trap environments \cite{partridge,stewart,luo}. The data is compared with the predictions of a recent strong interaction theory \cite{hldepl,hldpra}. Excellent agreement is obtained, with no adjustable parameters. By extrapolating to zero temperature, we show that the experimental measurements yield a many-body parameter} $\mathbf{\beta\simeq-0.59\pm.07}$, \textbf{describing the universal energy of strongly interacting Fermi gases.