Viscosity-entropy ratio of the unitary Fermi gas from zero-temperature elementary excitations
Abstract
We investigate the low-temperature behavior of the ratio between the shear viscosity η and the entropy density s in the unitary Fermi gas by using a model based on the zero-temperature spectra of both bosonic collective modes and fermonic single-particle excitations. Our theoretical curve of η/s as a function of the temperature T is in qualitative agreement with the experimental data of trapped ultracold 6Li atomic gases. We find the minimum value η/s 0.44 (in units of /kB) at the temperature T/TF 0.27, with TF the Fermi temperature.
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