John E. Thomas - Optically-Trapped Interacting Fermi Gases

Optically-trapped, ultra-cold gases of spin ½-up and spin ½-down 6Li atoms enable “designer” interactions, offering a versatile environment for simulating exotic quantum systems that span a vast range of energy. A strongly interacting gas is a scale-invariant, nearly perfect hydrodynamic system with universal transport coefficients, enabling parameter-free comparison with predictions, where there is currently some tension.  I will discuss our latest measurements in a “box” potential, where these coefficients are directly extracted from the time-dependent response of a cloud to small perturbations. Then I will discuss measurements of information scrambling in the very weakly interacting regime, where the cloud behaves as a large spin lattice in energy space, with effective long-range interactions.