Year: 2025
Type: article
Abstract: We investigate the two-dimensional motion of a single vortex orbiting a pinned anti-vortex in a unitary Fermi superfluid. By analyzing its trajectory, we measure the yet-unknown longitudinal and transverse mutual friction coefficients, which quantify the vortex-mediated coupling between the normal and superfluid components. Both coefficients increase while approaching the superfluid transition. They provide access to the vortex Hall angle, which is linked to the relaxation time of the localized quasiparticles occupying Andreev bound states within the vortex core, and to the vortex Reynolds number Reα associated with the transition from laminar to quantum turbulent flows. We compare our results with numerical simulations and an analytic model originally formulated for superfluid 3He, finding good agreement. Our work suggests that vortex dynamics in unitary Fermi superfluids is essentially affected by the interplay between delocalized thermal excitations and vortex-bound quasiparticles. Further, it provides a novel testbed for studying vortex dynamics at finite temperatures. Vortex dynamics and mutual friction in quantum fluids are intimately connected to the fundamental properties of superfluids. Here, the authors reveal previously unexplored mechanisms underlying the mutual friction coefficients in ultracold Fermi superfluids in the unitary limit, suggesting bound quasiparticles within the vortex core play a significant role.
Source: Nature Communications
Institutions: European Laboratory for Non-Linear Spectroscopy, National Institute of Optics, Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, University of Florence, Centre National de la Recherche Scientifique, Collège de France, Université Paris Sciences et Lettres, Laboratoire Kastler Brossel, École Normale Supérieure - PSL, Sorbonne Université, Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, University of Bologna, University of Augsburg, Max Planck Institute for the Physics of Complex Systems, Warsaw University of Technology, University of Washington, University of Trieste, National Research Council
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $6,990
Awards: G1605908383, G1848969253, Programmable Atomic Large-scale Quantum Simulation 2 - SGA1, G2460755258, G3022749744, G3237164968, G3269556148, G3514304032, The Integrated Initiative of European Laser Research Infrastructures, G3976037732, G4129145046, G434337789, G4856404060, G526456201, G5356239126, G5443090575, G5987792135, G7249932416, G7455520032, G7621391830, G777498305, G7919348612, G8597630144, G8959349008, G972786147
OpenAlex ID: W4416466413