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The Shear Viscosity to Entropy Density Ratio of Trapped Fermions in the Unitarity Limit

Thomas Schaefer
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Abstract

We extract the shear viscosity to entropy density ratio η/s of cold fermionic atoms in the unitarity limit from experimental data on the damping of collective excitations. We find that near the critical temperature η/s is roughly equal to 1/2 in units of \hbar/k_B. With the possible exception of the quark gluon plasma, this value is closer to the conjectured lower bound 1/(4π) than any other known liquid.

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Thomas Schaefer. 2008-01-25. The Shear Viscosity to Entropy Density Ratio of Trapped Fermions in the Unitarity Limit. https://doi.org/10.1103/physreva.76.063618

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