Viscosity of strongly interacting quantum fluids: Spectral functions and sum rules

Journal Article · Sat May 15 04:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.053610· OSTI ID:21408868

Taylor, Edward; Randeria, Mohit ^[1]

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1. Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)

The viscosity of strongly interacting systems is a topic of great interest in diverse fields. We focus here on the bulk and shear viscosities of nonrelativistic quantum fluids, with particular emphasis on strongly interacting ultracold Fermi gases. We use Kubo formulas for the bulk and shear viscosity spectral functions, {zeta}({omega}) and {eta}({omega}), respectively, to derive exact, nonperturbative results. Our results include a microscopic connection between the shear viscosity {eta} and the normal-fluid density {rho}{sub n}; sum rules for {zeta}({omega}) and {eta}({omega}) and their evolution through the BCS-BEC crossover (where BEC denotes Bose-Einstein condensate); and universal high-frequency tails for {eta}({omega}) and the dynamic structure factor S(q,{omega}). We use our sum rules to show that, at unitarity, {zeta}({omega}) is identically zero and thus relate {eta}({omega}) to density-density correlations. We predict that frequency-dependent shear viscosity {eta}({omega}) of the unitary Fermi gas can be experimentally measured using Bragg spectroscopy.

• OSTI ID: 21408868
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 5 Vol. 81; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
BOSE-EINSTEIN CONDENSATION
CORRELATIONS
DIMENSIONLESS NUMBERS
EQUATIONS
FERMI GAS
FLUIDS
FREQUENCY DEPENDENCE
FUNCTIONS
KUBO FORMULA
QUANTUM FLUIDS
SPECTRAL FUNCTIONS
SPECTROSCOPY
STRUCTURE FACTORS
SUM RULES
UNITARITY