Decay of Persistent Currents in Annular Atomic Superfluids

Anno: 2023

Autori: Xhani K., Del Pace G., Scazza F., Roati G.

Affiliazione autori: Ist Nazl Ott Consiglio Nazl Ric CNR INO LENS, I-50019 Sesto Fiorentino, Italy; Univ Florence, Dept Phys, 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.

Abstract: We investigate the role of vortices in the decay of persistent current states of annular atomic superfluids by solving numerically the Gross-Pitaevskii equation, and we directly compare our results with the Li-6 experiment at LENS data. We theoretically model the optical phase-imprinting technique employed to experimentally excite finite-circulation states in the Bose-Einstein condensation regime, accounting for imperfections of the optical gradient imprinting profile. By comparing simulations of this realistic protocol to an ideal imprinting, we show that the introduced density excitations arising from imperfect imprinting are mainly responsible for limiting the maximum reachable winding number w(max) in the superfluid ring. We also investigate the effect of a point-like obstacle with variable potential height V-0 on the decay of circulating supercurrents. For a given obstacle height, a critical circulation w(c) exists, such that for an initial circulation w(0) larger than w(c) the supercurrent decays through the emission of vortices, which cross the superflow and thus induce phase slippage. Higher values of the obstacle height V-0 further favor the entrance of vortices, thus leading to lower values of w(c). Furthermore, the stronger vortex-defect interaction at higher V-0 leads to vortices that propagate closer to the center of the ring condensate. The combination of both these effects leads to an increase in the supercurrent decay rate for increasing w(0), in agreement with experimental observations.

Giornale/Rivista: ATOMS

Volume: 11 (8)      Da Pagina: 109-1  A: 109-12

Maggiori informazioni: The authors acknowledge the LiLab experimental team at LENS, and especially Nicola Grani and Diego Hernandez-Rajkov, for providing data of the spurious vortices number, and Woo Jin Kwon, for stimulating discussions.
Parole chiavi: Bose-Einstein condensates; persistent currents; superfluids; vortices; phase-slippage; solitons
DOI: 10.3390/atoms11080109

Citazioni: 7
dati da “WEB OF SCIENCE” (of Thomson Reuters) aggiornati al: 2025-06-15
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