Dynamics of a highly-degenerate, strongly-interacting Fermii gas of atoms

We use all-optical methods to produce a highly-degenerate, Fermi gas of ⁶ Li atoms near a Feshbach resonance, where strong interactions are predicted. In this regime, the zero-energy scattering length is larger than the interparticle spacing, and both the mean field energy and the collision rate take on universal forms as a consequence of unitarity and many-body interactions. Our experiments study universal hydrodynamic expansion of the gas and universal mean field interactions. By measuring the cloud radii of the trapped gas, we determine a universal parameter for strongly interacting two-component Fermi systems, the ratio of the mean field energy to the kinetic energy.