Abstract
We determine the shear viscosity of the ultracold Fermi gas at unitarity in the normal phase using hydrodynamic expansion data. The analysis is based on a generalized fluid dynamic framework which ensures a smooth transition between the fluid dynamic core of the cloud and the ballistic corona. We use expansion data taken by Joseph, Elliott, and Thomas [Shear Viscosity of a Universal Fermi Gas Near the Superfluid Phase Transition, Phys. Rev. Lett. 115, 020401 (2015).] and measurements of the equation of state by Ku et al. [Revealing the superfluid lambda transition in the universal thermodynamics of a unitary Fermi gas, Science 335, 563 (2012).]. We find that the shear viscosity to particle density ratio just above the critical temperature is . We also obtain evidence that the shear viscosity to entropy density ratio has a minimum slightly above with .
- Received 16 April 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.065302
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