Is a gas of strongly interacting atomic fermions a nearly perfect fluid?
arXiv:0707.2574 · doi:10.1007/s10909-007-9589-1
Abstract
We use all-optical methods to produce a highly-degenerate Fermi gas of spin-1/2 Li atoms. A magnetic field tunes the gas near a collisional (Feshbach) resonance, producing strong interactions between spin-up and spin-down atoms. This atomic gas is a paradigm for strong interactions in nature, and provides tests of current quantum many-body calculational methods for diverse systems, including very high temperature superconductors, nuclear matter in neutron stars, and the quark-gluon plasma of the Big Bang. We have measured properties of a breathing mode over a wide range of temperatures. At temperatures both below and well above the superfluid transition, the frequency of the mode is nearly constant and very close to the hydrodynamic value. However, explaining both the frequency and the damping rate in the normal collisional regime has not been achieved. Our measurements of the damping rate as a function of the energy of the gas are used to estimate an upper bound on the viscosity. Using our new measurements of the entropy of the gas, we estimate the ratio of the shear viscosity to the entropy density, and compare the result with the lower bound for quantum viscosity recently predicted using string theory methods.
10 pages, 5 figures
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Cited by in corpus (18)
- Many-Body Physics with Ultracold Gases
- Toward an AdS/cold atoms correspondence: a geometric realization of the Schroedinger symmetry
- Universal Quantum Viscosity in a Unitary Fermi Gas
- Observation of a two-dimensional Fermi gas of atoms
- Viscosity and scale invariance in the unitary Fermi gas
- Fluid Dynamics and Viscosity in Strongly Correlated Fluids
- First and second sound in a strongly interacting Fermi gas
- Spin diffusion in Fermi gases
- Shear Viscosity of a Unitary Fermi Gas
- SU(1,1) echoes for breathers in quantum gases
- Microscopic Approach to Shear Viscosities in Superfluid Gases: From BCS to BEC
- Shear viscosity and spin diffusion in a two-dimensional Fermi gas
- Minimum Shear Viscosity over Entropy Density at Phase Transition? --- A Counterexample
- Relation connecting thermodynamics and transport of atomic unitary Fermi superfluids
- Shear Viscosity in Weakly Coupled N-Component Scalar Field Theories
- Dissipative superfluid hydrodynamics for the unitary Fermi gas
- Finite Temperature Behaviors of q-deformed Fermi Gases
- Exact perturbative expansion of the transport coefficients of a normal low-temperature Fermi gas with contact interactions