Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/81620

Download PDF (Accepted manuscript) (Adobe Acrobat PDF, -1 bytes)

Title

Variational theory of two-fluid hydrodynamic modes at unitarity

Author(s)

Taylor, E.;  Hu, H.;  Liu, X.-J.;  Griffin, A.

Abstract

We present the results of a variational calculation of the frequencies of the low-lying Landau two-fluid hydrodynamic modes in a trapped Fermi superfluid gas at unitarity. Landau's two-fluid hydrodynamics is expected to be the correct theory of Fermi superfluids at finite temperatures close to unitarity, where strong interactions give rise to collisional hydrodynamics. Two-fluid hydrodynamics predicts the existence of in-phase modes in which the superfluid and normal fluid components oscillate together, as well as out-of-phase modes where the two components move against each other. We prove that, at unitarity, the dipole and breathing in-phase modes are locally isentropic. Their frequencies are independent of temperature and are the same above and below the superfluid transition, a feature due as much to the harmonic trapping potential as to the thermodynamic properties at unitarity. The out-of-phase modes, in contrast, are strongly dependent on temperature and hence can be used to test the thermodynamic properties and superfluid density of a Fermi gas at unitarity. We give numerical results for the frequencies of these modes as function of temperature in an isotropic trap at unitarity.

Publication type

Journal article

Source

Physical Review A: Atomic, Molecular, and Optical Physics, Vol. 77, no. 3 (Mar 2008), article no. 033608

Publication year

2008

FOR Code(s)

0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics;  0204 Condensed Matter Physics;  0205 Optical Physics

Keyword(s)

Charge trapping;  Fermi level;  Hydrodynamics;  Isotropic trap;  Phase transitions;  Two phase flow;  Two-fluid hydrodynamic;  Variational techniques;  Variational theory

Publisher

American Physical Society

ISSN

1050-2947

Publisher URL

http://dx.doi.org/10.1103/PhysRevA.77.033608

Copyright

Copyright © 2008 The American Physical Society. The accepted manuscript of the paper is reproduced here for noncommerical purposes only in accordance with the copyright policy of the publisher.

Full text

Peer reviewed