Measurement of the Entropy and Critical Temperature of a Strongly Interacting Fermi Gas

TL;DR

This paper presents a model-independent experimental method to measure the entropy, energy, and critical temperature of a strongly interacting Fermi gas, providing insights into its thermodynamic properties.

Contribution

It introduces a novel, model-independent approach to determine thermodynamic quantities of a strongly interacting Fermi gas using adiabatic magnetic field sweeps.

Findings

Measured entropy and energy of the Fermi gas.

Quantitative test of finite-temperature thermodynamics predictions.

Determined the critical temperature of the strongly interacting Fermi gas.

Abstract

We report a model-independent measurement of the entropy, energy, and critical temperature of a degenerate, strongly interacting Fermi gas of atoms. The total energy is determined from the mean square cloud size in the strongly interacting regime, where the gas exhibits universal behavior. The entropy is measured by sweeping a bias magnetic field to adiabatically tune the gas from the strongly interacting regime to a weakly interacting regime, where the entropy is known from the cloud size after the sweep. The dependence of the entropy on the total energy quantitatively tests predictions of the finite-temperature thermodynamics.