Perfect-fluid behavior of a dilute Fermi gas near unitary

Abstract

We present an ab initio calculation of the shear viscosity as a function of interaction strength in a two-component unpolarized Fermi gas near the unitary limit, within a finite temperature quantum Monte Carlo (QMC) framework and using the Kubo linear-response formalism. The shear viscosity decreases as we tune the interaction strength 1/ak_F from the Bardeen-Cooper-Schrieffer side of the Feshbach resonance towards Bose-Einstein condensation limit and it acquires the smallest value for 1/ak_F approx 0.4, with a minimum value of (eta/s)_min approx 0.2 hbar/k_B, which is about twice as small as the value reported for experiments in quark-gluon plasma (eta/s)_QGP lesssim 0.4 hbar/k_B. The Fermi gas near unitarity thus emerges as the most "perfect fluid" observed so far in nature. The clouds of dilute Fermi gas near unitarity exhibit the unusual attribute that, for the sizes realized so far in the laboratory or larger (less than 10^9 atoms), can sustain quantum turbulence below the critical temperature, but at the same time the classical turbulence is suppressed in the normal phase.

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Cited by in corpus (13)

• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Quantum turbulence in trapped atomic Bose-Einstein condensates
• Observation of quantum-limited spin transport in strongly interacting two-dimensional Fermi gases
• Quantum turbulence in quantum gases
• High-temperature expansion of the viscosity in interacting quantum gases
• Towards Quantum Turbulence in Cold Atomic Fermionic Superfluids
• The Shear Viscosity in an Anisotropic Unitary Fermi Gas
• Quantum turbulence in Bose-Einstein condensates: present status and new challenges ahead
• Mesoscopic dynamics of fermionic cold atoms ---Quantitative analysis of transport coefficients and relaxation times---
• Sensitivity to the initial conditions of the Time-Dependent Density Functional Theory
• Shear viscosity over entropy density ratio with extended quasi-particles
• Kovtun-Son-Starinets Conjecture and Effects of Mass Imbalance in the Normal State of an Ultracold Fermi Gas in the BCS-BEC Crossover Region
• Fission in a microscopic framework: from basic science to support for applications