4 p.m. - 5 p.m. Location: SLC 1.102
Dr. John Thomas (North Carolina State University)
Optically-trapped, ultra-cold gases of spin ½-up and spin ½-down 6Li atoms model high temperature superconductors, neutron matter, and even the hydrodynamics of a quark-gluon plasma, a state of matter at 2 trillion degrees that existed microseconds after the Big Bang. A bias magnetic field tunes the gas to a collisional (Feshbach) resonance, where the dilute atomic cloud becomes a scale-invariant, strongly-interacting fluid: Shock waves are produced when two clouds collide. Remarkably, the ratio of the shear viscosity to the entropy density of such clouds is comparable to that of a quark-gluon plasma, close to the minimum ratio conjectured for a “perfect fluid” using scale-invariant conformal field theory methods. I will describe our recent observations of scale-invariant expansion in Fermi gases and the status of our studies of the quantum shear viscosity.