2018/01/31 by Matthew P. Gochan, M P Gochan, Hua Li +2
Physics and Astronomy · #Black Holes and Theoretical Physics #Entropy (arrow of time) #Fermi Gamma-ray Space Telescope #Fermi gas #Fermi liquid theory #Quantum Chromodynamics and Particle Interactions #Quantum many-body systems #Superfluidity #Unitarity #Unitary state #Upper and lower bounds #cond-mat.str-el
paper · pdf · doi:10.1088/2399-6528/ab292b
13 pages, 4 figures. J. Phys. Commun. (2019)
openalex created_date 2018/02/02 · arxiv created 2019/05/22 · openalex publication_date 2019/06/01 · arxiv updated 2019/06/28 · openalex updated_date 2026/08/05
The anti-de Sitter/conformal field theory correspondence (AdS/CFT) has been used to determine a lower bound on the ratio of shear viscosity to entropy density ( s ) for strongly-coupled field theories with a gravity dual. The conjectured universal lower bound, given as , is a measure of interaction strength in a quantum fluid where equality indicates a perfect quantum fluid. In this paper we study η / s in a Fermi gas in the unitary limit. We show that in addition to a local minimum for η / s at which obeys the lower bound, a more interesting result exists in the violation of the η / s lower bound due to the superfluid fluctuations above T c . To conclude, we examine the viscoelastic properties of the unitary Fermi gas. Previous work brought to light the connection between violation of the η / s bound and a viscoelastic response in the context of holographic solids. We ultimately find that, in addition to holographic solids, all Fermi liquids with a viscoelastic response produced by superfluid fluctuations can violate the universal η / s lower bound.