Riemann Rarefaction Waves in a Strongly Interacting Fermi Gas (opens in new tab)

We investigate the expansion of a homogeneous, strongly interacting Fermi gas released into vacuum in a ``shock tube'' geometry. At unitarity, where the gas is scale invariant and nearly inviscid, we find that the resulting rarefaction wave dynamics are self-similar and in excellent agreement with Riemann's solution of the Euler equation for all temperatures probed. Probing interactions away from unitarity within the BEC-BCS crossover, we observ...