First and second sound in cylindrically trapped gases

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 wave length limit. We provide quantitative predictions for the two sound velocities of a superfluid Fermi gas at unitarity. For shorter wave-lengths we discover a new surprising class of excitations continuously spread over a finite interval of frequencies. This results in a non-dissipative damping in the response function which is analytically calculated in the limiting case of a classical ideal gas.

4 pages, 2 figures. Published version in Phys. Rev. Lett

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• Heavy Solitons in a Fermionic Superfluid
• Observation of shock waves in a strongly interacting Fermi gas
• The critical velocity in the BEC-BCS crossover
• Universal Sound Diffusion in a Strongly Interacting Fermi Gas
• Collective Modes in a Unitary Fermi Gas across the Superfluid Phase Transition
• From a complex scalar field to the two-fluid picture of superfluidity
• First and second sound in a highly elongated Fermi gas at unitarity
• Scaling solutions of the two fluid hydrodynamic equations in a harmonically trapped gas at unitarity
• Reversible Dissipative Processes, Conformal Motions and Landau Damping
• Second sound with ultracold atoms: A brief historical account
• First and second sound of a unitary Fermi gas in highly oblate harmonic traps
• Mean-field description of pairing effects, BKT physics, and superfluidity in 2D Bose gases
• First and second sound in a two-dimensional dilute Bose gas across the Berezinskii-Kosterlitz-Thouless transition
• First and second sound of a unitary Fermi gas in highly elongated harmonic traps
• Extreme dynamics and relaxation of quantum gases: A hydrodynamic approach