Propagation of first and second sound in a two-dimensional Fermi superfluid

• Verfasst von: Tononi, Andrea [VerfasserIn]
• Verfasst von: Cappellaro, A. [VerfasserIn]
• Verfasst von: Bighin, Giacomo [VerfasserIn]
• Verfasst von: Salasnich, L. [VerfasserIn]
• Titel: Propagation of first and second sound in a two-dimensional Fermi superfluid
• Verf.angabe: A. Tononi, A. Cappellaro, G. Bighin, and L. Salasnich
• E-Jahr: 2021
• Jahr: 14 June 2021
• Umfang: 6 S.
• Teil: volume:103
• Teil: year:2021
• Teil: number:6
• Teil: elocationid:L061303
• Teil: pages:1-6
• Teil: extent:6
• Fussnoten: Gesehen am 13.08.2021
• Titel Quelle: Enthalten in: Physical review
• Ort Quelle: Woodbury, NY : Inst., 2016
• Jahr Quelle: 2021
• Band/Heft Quelle: 103(2021), 6, Artikel-ID L061303, Seite 1-6
• ISSN Quelle: 2469-9934
• DOI: doi:10.1103/PhysRevA.103.L061303
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1766795722

Abstract

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.