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

Abstract

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.

Authors:
;  [1]
  1. Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)
Publication Date:
OSTI Identifier:
21408868
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 81; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.81.053610; (c) 2010 The American Physical Society; Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; BOSE-EINSTEIN CONDENSATION; CORRELATIONS; FERMI GAS; FREQUENCY DEPENDENCE; KUBO FORMULA; QUANTUM FLUIDS; SPECTRAL FUNCTIONS; SPECTROSCOPY; STRUCTURE FACTORS; SUM RULES; UNITARITY; DIMENSIONLESS NUMBERS; EQUATIONS; FLUIDS; FUNCTIONS

Citation Formats

Taylor, Edward, and Randeria, Mohit. Viscosity of strongly interacting quantum fluids: Spectral functions and sum rules. United States: N. p., 2010. Web. doi:10.1103/PHYSREVA.81.053610.
Taylor, Edward, & Randeria, Mohit. Viscosity of strongly interacting quantum fluids: Spectral functions and sum rules. United States. https://doi.org/10.1103/PHYSREVA.81.053610
Taylor, Edward, and Randeria, Mohit. 2010. "Viscosity of strongly interacting quantum fluids: Spectral functions and sum rules". United States. https://doi.org/10.1103/PHYSREVA.81.053610.
@article{osti_21408868,
title = {Viscosity of strongly interacting quantum fluids: Spectral functions and sum rules},
author = {Taylor, Edward and Randeria, Mohit},
abstractNote = {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.},
doi = {10.1103/PHYSREVA.81.053610},
url = {https://www.osti.gov/biblio/21408868}, journal = {Physical Review. A},
issn = {1050-2947},
number = 5,
volume = 81,
place = {United States},
year = {Sat May 15 00:00:00 EDT 2010},
month = {Sat May 15 00:00:00 EDT 2010}
}