Measurement of Universal Thermodynamic Functions for a Unitary Fermi Gas

Abstract

Dissecting Fermion Interactions Electrons, protons, and other building blocks of our universe belong to a class of particles we call fermions. Different interfermion interactions give rise to different forms of matter. In the strongly interacting resonant regime, however, fermionic systems have thermodynamic properties that depend only on the interparticle spacing and scaled temperature. Horikoshi et al. (p. 442 ; see the Perspective by Marwan ) precisely characterize the thermodynamics in this universal regime for a system of ultracold fermionic lithium atoms. Analysis of a large number of trapped-gas density profiles confirms that the results depend neither on trap geometry nor the absolute temperature of the gas. The results are relevant to studies of all strongly interacting fermionic systems, including neutron stars and nuclear matter.