# Universal quantum viscosity in a unitary Fermi gas.

Published

Journal Article

A Fermi gas of atoms with resonant interactions is predicted to obey universal hydrodynamics, in which the shear viscosity and other transport coefficients are universal functions of the density and temperature. At low temperatures, the viscosity has a universal quantum scale ħ n, where n is the density and ħ is Planck's constant h divided by 2π, whereas at high temperatures the natural scale is p(T)(3)/ħ(2), where p(T) is the thermal momentum. We used breathing mode damping to measure the shear viscosity at low temperature. At high temperature T, we used anisotropic expansion of the cloud to find the viscosity, which exhibits precise T(3/2) scaling. In both experiments, universal hydrodynamic equations including friction and heating were used to extract the viscosity. We estimate the ratio of the shear viscosity to the entropy density and compare it with that of a perfect fluid.

### Full Text

### Duke Authors

### Cited Authors

- Cao, C; Elliott, E; Joseph, J; Wu, H; Petricka, J; Schäfer, T; Thomas, JE

### Published Date

- January 2011

### Published In

### Volume / Issue

- 331 / 6013

### Start / End Page

- 58 - 61

### PubMed ID

- 21148347

### Pubmed Central ID

- 21148347

### Electronic International Standard Serial Number (EISSN)

- 1095-9203

### International Standard Serial Number (ISSN)

- 0036-8075

### Digital Object Identifier (DOI)

- 10.1126/science.1195219

### Language

- eng