Imprinting Persistent Currents in Tunable Fermionic Rings

Year: 2022

Authors: Del Pace G., Xhani K., Falconi AM., Fedrizzi M., Grani N., Rajkov DH., Inguscio M., Scazza F., Kwon WJ., Roati G.

Autors Affiliation: Univ Florence, Consiglio Nazl Ric, CNR, Ist Nazl Ott,INO, I-50019 Sesto Fiorentino, Italy; Univ Florence, European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy; Univ Trieste, Dept Phys, I-34127 Trieste, Italy; Univ Florence, Dept Phys & Astron, I-50019 Sesto Fiorentino, Italy; Campus Biomed Univ Rome, Dept Engn, I-00128 Rome, Italy; Ecole Polytech Fed Lausanne, Inst Phys, CH-1015 Lausanne, Switzerland; Ulsan Natl Inst Sci & Technol UNIST, Dept Phys, Ulsan 44919, South Korea.

Abstract: Persistent currents in annular geometries have played an important role in disclosing the quantum phase coherence of superconductors and mesoscopic electronic systems. Ultracold atomic gases in multiply connected traps also exhibit long-lived supercurrents and have attracted much interest both for fundamental studies of superfluid dynamics and as prototypes for atomtronics circuits. Here, we report on the realization of supercurrents in homogeneous, tunable fermionic rings. We gain exquisite, rapid control over quantized persistent currents in all regimes of the BCS-BEC crossover through a universal phase-imprinting technique, attaining on-demand circulations w as high as 9. High-fidelity readout of the superfluid circulation state is achieved by exploiting an interferometric protocol, which also yields local information about the superfluid phase around the ring. In the absence of externally introduced perturbations, we find the induced metastable supercurrents to be as long-lived as the atomic sample. Conversely, we trigger and inspect the supercurrent decay by inserting a single small obstacle within the ring. For circulations higher than a critical value, the quantized current is observed to dissipate via the emission of vortices, i.e., quantized phase slips, which we directly image, in good agreement with numerical simulations. The critical circulation at which the superflow becomes unstable is found to depend starkly on the interaction strength, taking its maximum value for the unitary Fermi gas. Our results demonstrate fast and accurate control of quantized collective excitations in a macroscopic quantum system and establish strongly interacting fermionic superfluids as excellent candidates for atomtronics applications.

Journal/Review: PHYSICAL REVIEW X

Volume: 12 (4)      Pages from: 41037-1  to: 41037-16

More Information: We thank L. Amico, T. Giamarchi, A. Minguzzi, L. Pezze, and the Quantum Gases group at LENS for fruitful discussions. This work was supported by the European Research Council under Grant Agreement No. 307032, the Italian Ministry of University and Research under the PRIN2017 project CEnTraL, and European Union’s Horizon 2020 research and innovation program under the Qombs project FET Flagship on Quantum Technologies Grant Agreement No. 820419 and Marie Skodowska-Curie Grant Agreement No. 843303.
KeyWords: Magnetic Flux; Order; Solitons
DOI: 10.1103/PhysRevX.12.041037

Citations: 36
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