Propagation of first and second sound in a two-dimensional Fermi superfluid
Sound propagation is a macroscopic manifestation of the interplay between the equilibrium thermodynamics and the dynamical transport properties of fluids. Here, for a two-dimensional system of ultracold fermions, we calculate the first and second sound velocities across the whole BCS-BEC crossover,...
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| Main Authors: | , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
14 June 2021
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| In: |
Physical review
Year: 2021, Volume: 103, Issue: 6, Pages: 1-6 |
| ISSN: | 2469-9934 |
| DOI: | 10.1103/PhysRevA.103.L061303 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1103/PhysRevA.103.L061303 Verlag, lizenzpflichtig, Volltext: https://link.aps.org/doi/10.1103/PhysRevA.103.L061303 
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| Author Notes: | A. Tononi, A. Cappellaro, G. Bighin, and L. Salasnich |
| Summary: | Sound propagation is a macroscopic manifestation of the interplay between the equilibrium thermodynamics and the dynamical transport properties of fluids. Here, for a two-dimensional system of ultracold fermions, we calculate the first and second sound velocities across the whole BCS-BEC crossover, and we analyze the system response to an external perturbation. In the low-temperature regime we reproduce the recent measurements [Phys. Rev. Lett. 124, 240403 (2020)] of the first sound velocity, which, due to the decoupling of density and entropy fluctuations, is the sole mode excited by a density probe. Conversely, a heat perturbation excites only the second sound, which, being sensitive to the superfluid depletion, vanishes in the deep BCS regime and jumps discontinuously to zero at the Berezinskii-Kosterlitz-Thouless superfluid transition. A mixing between the modes occurs only in the finite-temperature BEC regime, where our theory converges to the purely bosonic results. |
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| Item Description: | Gesehen am 13.08.2021 |
| Physical Description: | Online Resource |
| ISSN: | 2469-9934 |
| DOI: | 10.1103/PhysRevA.103.L061303 |