First and Second Sound in Cylindrically Trapped Gases

Year: 2010

Authors: Bertaina G., Pitaevskii L., Stringari S.

Autors Affiliation: Univ Trent, INO CNR BEC Ctr, I-38123 Povo, Trento, Italy; Univ Trent, Dipartimento Fis, I-38123 Povo, Trento, Italy; PL Kapitza Phys Problems Inst, Moscow 119334, Russia.

Abstract: We investigate the propagation of density and temperature waves in a cylindrically trapped gas with radial harmonic confinement. Starting from two-fluid hydrodynamic theory we derive effective 1D equations for the chemical potential and the temperature which explicitly account for the effects of viscosity and thermal conductivity. Differently from quantum fluids confined by rigid walls, the harmonic confinement allows for the propagation of both first and second sound in the long wavelength limit. We provide quantitative predictions for the two sound velocities of a superfluid Fermi gas at unitarity. For shorter wavelengths we discover a new surprising class of excitations continuously spread over a finite interval of frequencies. This results in a nondissipative damping in the response function which is analytically calculated in the limiting case of a classical ideal gas.

Journal/Review: PHYSICAL REVIEW LETTERS

Volume: 105 (15)      Pages from: 150402-1  to: 150402-4

More Information: We thank our collaborators H. Hu, E. Taylor, and A. Griffin for important suggestions that led to our work, and P. Hohenberg, C. Salomon, H. Stoof, and P. van der Straten for useful discussions. We also thank the authors of [18-21] for providing us with tables of their results. Financial support from the EuroQUAM Fermix program and from MIUR PRIN is acknowledged.
KeyWords: Bose-einstein Transition; Hydrodynamic Modes; Fermi Gases; Helium-ii; Propagation
DOI: 10.1103/PhysRevLett.105.150402

Citations: 21
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