Ultracold strongly coupled gas: A near-ideal liquid

Journal Article · Sat Oct 15 00:00:00 EDT 2005 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.72.043601· OSTI ID:20718773

Gelman, Boris A; Shuryak, Edward V; Zahed, Ismail ^[1]

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1. Department of Physics and Astronomy, State University of New York, Stony Brook, New York 11794-3800 (United States)

Feshbach resonances of trapped ultracold alkali-metal atoms allow to vary the atomic scattering length a. At very large values of a the system enters an universal strongly coupled regime in which its properties--the ground-state energy, pressure, etc.--become independent of a. We discuss the transport properties of such systems. In particular, the universality arguments imply that the shear viscosity of ultracold Fermi atoms at the Feschbach resonance is proportional to the particle number density n and the Plank constant ({Dirac_h}/2{pi}): {eta}=({Dirac_h}/2{pi})n{alpha}{sub {eta}}, where {alpha}{sub {eta}} is a universal constant. Using Heisenberg uncertainty principle and Einstein's relation between diffusion and viscosity we argue that the viscosity has the lower bound given by {alpha}{sub {eta}}{<=}(6{pi}){sup -1}. We relate the damping of low-frequency density oscillations of ultracold optically trapped {sup 6}Li atoms to viscosity and find that the value of the coefficient {alpha}{sub {eta}} is about 0.3. We also show that such a small viscosity cannot be explained by kinetic theory based on binary scattering. We conclude that the system of ultracold atoms near the Feshbach resonance is a near-ideal liquid.

• OSTI ID: 20718773
• Journal Information: Physical Review. A, Vol. 72, Issue 4; Other Information: DOI: 10.1103/PhysRevA.72.043601; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMS
DAMPING
DENSITY
DIFFUSION
FERMIONS
GROUND STATES
LIQUIDS
LITHIUM
LITHIUM 6
OSCILLATIONS
PHOTON-ATOM COLLISIONS
RESONANCE
SCATTERING
SCATTERING LENGTHS
SHEAR
TRAPPING
UNCERTAINTY PRINCIPLE
VISCOSITY