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Implications of hydrodynamic fluctuations for the minimum shear viscosity of the dilute Fermi gas at unitarity

2013; American Physical Society; Volume: 87; Issue: 5 Linguagem: Inglês

10.1103/physreva.87.053606

1538-4446

Paul Romatschke, Ryan E. Young,

Quantum, superfluid, helium dynamics

We confirm and expand on work by Chafin and Sch\"afer [Phys. Rev. A 87, 023629 (2013)] on hydrodynamic fluctuations in the unitary Fermi gas. Using the result for the equation of state from a recent MIT experiment, we derive lower bounds for $\ensuremath{\eta}/n$ and $\ensuremath{\eta}/s$ as a function of temperature. Reanalyzing recent quantum Monte Carlo data for the shear-viscosity spectral function, we point out a possible resolution for the tension between the viscosity bound $\ensuremath{\eta}/n\ensuremath{\gtrsim}0.3$ from Chafin and Sch\"afer and the quantum Monte Carlo results $\ensuremath{\eta}/n\ensuremath{\lesssim}0.2$ from Wlazlowski, Magierski, and Drut [Phys. Rev. Lett. 109, 020406 (2012)] near the critical temperature.