Two-fluid hydrodynamic modes in a trapped superfluid gas

Journal Article · Tue Nov 15 04:00:00 EST 2005 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.72.0· OSTI ID:20786576

Taylor, E; Griffin, A ^[1]

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1. Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 (Canada)

In the collisional region at finite temperatures, the collective modes of superfluids are described by the Landau two-fluid hydrodynamic equations. This region can now be probed over the entire BCS-Bose-Einstein-condensate crossover in trapped Fermi superfluids with a Feshbach resonance, including the unitarity region. Building on the approach initiated by Zaremba, Nikuni, and Griffin in 1999 for trapped atomic Bose gases, we present a variational formulation of two-fluid hydrodynamic collective modes based on the work of Zilsel in 1950 developed for superfluid helium. Assuming a simple variational Ansatz for the superfluid and normal fluid velocities, the frequencies of the hydrodynamic modes are given by solutions of coupled algebraic equations, with constants only involving spatial integrals over various equilibrium thermodynamic derivatives. This variational approach is both simpler and more physical than a direct attempt to solve the Landau two-fluid differential equations. Our two-fluid results are shown to reduce to those of Pitaevskii and Stringari for a pure superfluid at T=0.

• OSTI ID: 20786576
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 5 Vol. 72; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
ALGEBRA
BOSE-EINSTEIN CONDENSATION
BOSE-EINSTEIN GAS
DIFFERENTIAL EQUATIONS
EQUILIBRIUM
FERMIONS
HELIUM
HYDRODYNAMICS
MATHEMATICAL SOLUTIONS
RADIATION PRESSURE
RESONANCE
SUPERFLUIDITY
TRAPPING
UNITARITY
VARIATIONAL METHODS