First and second sound in a strongly interacting Fermi gas

Abstract

Using a variational approach, we solve the equations of two-fluid hydrodynamics for a uniform and trapped Fermi gas at unitarity. In the uniform case, we find that the first and second sound modes are remarkably similar to those in superfluid Helium, a consequence of strong interactions. In the presence of harmonic trapping, first and second sound become degenerate at certain temperatures. At these points, second sound hybridizes with first sound and is strongly coupled with density fluctuations, giving a promising way of observing second sound. We also discuss the possibility of exciting second sound by generating local heat perturbations.

Published version. 7 pages, 4 figures

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• Apparent low-energy scale invariance in two-dimensional Fermi gases
• Collective Modes in a Unitary Fermi Gas across the Superfluid Phase Transition
• Tunneling transport of unitary fermions across the superfluid transition
• Thermal Conductivity and Sound Attenuation in Dilute Atomic Fermi Gases
• Scale breaking and fluid dynamics in a dilute two-dimensional Fermi gas
• Reduced quantum anomaly in a quasi-2D Fermi superfluid: The significance of the confinement-induced effective range of interactions
• Thermography of the superfluid transition in a strongly interacting Fermi gas
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• From a complex scalar field to the two-fluid picture of superfluidity
• Second sound and the density response function in uniform superfluid atomic gases
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• Predicting Energies of Small Clusters from the Inhomogeneous Unitary Fermi Gas
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• Collective modes of a one-dimensional trapped atomic Bose gas at finite temperatures
• Hydrodynamic VS collisionless dynamics of a 1D harmonically trapped Bose gas
• Phononic collective excitations in superfluid Fermi gases at nonzero temperatures
• Collective excitations of a trapped Fermi gas at finite temperature
• Pair excitations and parameters of state of imbalanced Fermi gases at finite temperatures
• Hybridization of first and second sound in a weakly-interacting Bose gas
• Collective modes of a two-dimensional Fermi gas at finite temperature
• Role reversal in first and second sound in a relativistic superfluid
• Hydrodynamic Modes of a holographic $p-$ wave superfluid
• Few-body perspective of a quantum anomaly in two-dimensional Fermi gases
• Second sound with ultracold atoms: A brief historical account
• Berezinskii-Kosterlitz-Thouless phase transition with Rabi-coupled bosons
• Sound modes in collisional superfluid Bose gases
• Two-fluid theory for superfluid system with anisotropic effective masses
• Dynamical Kosterlitz-Thouless Theory for Two-Dimensional Ultracold Atomic Gases
• Thermodynamic measurement of the sound velocity of a Bose gas across the transition to Bose-Einstein condensation
• First and second sound in a two-dimensional dilute Bose gas across the Berezinskii-Kosterlitz-Thouless transition
• Probing an effective-range-induced super fermionic Tonks-Girardeau gas with ultracold atoms in one-dimensional harmonic traps
• Superfluid density reduction and spin-imbalanced pairing in a fermionic superfluid due to dynamical boson exchange
• Second sound in the BEC-BCS crossover
• Probing the critical exponent of superfluid fraction in a strongly interacting Fermi gas
• First and second sound of a unitary Fermi gas in highly elongated harmonic traps