Mutual friction and vortex Hall angle in a strongly interacting Fermi superfluid

Year: 2025

Authors: Grani N., Hernandez-Rajkov D., Daix C., Pieri P., Pini M., Magierski P., Wlazlowski G., Fernandez MF., Scazza F., Del Pace G., Roati G.

Autors Affiliation: Univ Florence, Dept Phys, Sesto Fiorentino, Italy; Univ Florence, European Lab Nonlinear Spect LENS, Sesto Fiorentino, Italy; CNR, Ist Nazl Ott, INO, LENS, Sesto Fiorentino, Italy; INFN, Sez Firenze, Sesto Fiorentino, Italy; Univ Bologna, Dept Phys & Astron, Bologna, Italy; INFN, Sez Bologna, Bologna, Italy; Univ Augsburg, Inst Phys, Ctr Elect Correlat & Magnetism, Theoret Phys 3, Augsburg, Germany; Max Planck Inst Phys Komplexer Syst, Dresden, Germany; Warsaw Univ Technol, Fac Phys, Warsaw, Poland; Univ Washington, Dept Phys, Seattle, WA USA; CNR, Ist Nazl Ott, INO, Trieste, Italy; Univ Trieste, Dept Phys, I-34127 Trieste, Italy; Sorbonne Univ, Univ PSL, Coll France, CNRS,ENS,Lab Kastler Brossel, 24 Rue Lhomond, Paris, France.

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 Re alpha 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.

Journal/Review: NATURE COMMUNICATIONS

Volume: 16 (1)      Pages from: 10245-1  to: 10245-11

More Information: We thank B. Haskell, M. Antonelli, and S. Autti for the discussions. We thank M. Inguscio, J. Makinen and D. Galli for careful reading of the manuscript, and W.J. Kwon for participating in the initial setting of the experiment. G.R., G.D.P., and P.P. acknowledge financial support from the PNRR MUR project PE0000023-NQSTI. G.R. acknowledges funding from the Italian Ministry of University and Research under the PRIN2017 project CEnTraL and the Project CNR-FOE-LENS-2024. The authors acknowledge funding from INFN through the RELAQS project. The authors acknowledge support from the European Union – NextGenerationEU for the Integrated Infrastructure initiative in Photonics and Quantum Sciences – I-PHOQS [IR0000016, ID D2B8D520, CUP B53C22001750006]. This publication has received funding under the Horizon Europe program HORIZON-CL4-2022-QUANTUM-02-SGA via project 101113690 (PASQuanS2.1) and by the European Community’s Horizon 2020 research and innovation program under grant agreement n degrees 871124. This work was financially supported by the (Polish) National Science Center Grants No. 2022/45/B/ST2/00358 (G.W.) and 2021/43/B/ST2/01191 (P.M.). P.P. acknowledges funding from the Italian Ministry of University and Research (MUR) under project PRIN2022, Contract No. 2022523NA7 and from the European Union – Next Generation EU through MUR project PNRR – M4C2 – I1.4 Contract No. CN00000013. F.S. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant agreement No. 949438). We acknowledge Polish high-performance computing infrastructure PLGrid for awarding this project access to the LUMI supercomputer, owned by the EuroHPC Joint Undertaking, hosted by CSC (Finland) and the LUMI consortium through PLL/2024/07/017603.
KeyWords: Liquid-helium; Vortices; Dynamics; Sound; Superconductors; Transition; He-3-b; States; Force; Line
DOI: 10.1038/s41467-025-64992-w