Pezzè Luca, Xhani Klejdja, Daix Cyprien, Grani Nicola, Donelli Beatrice, Scazza Francesco, Hernandez-Rajkov Diego, Kwon Woo Jin, Del Pace Giulia, Roati Giacomo
Istituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche (CNR-INO), Largo Enrico Fermi 6, Firenze, 50125, Italy.
European Laboratory for Nonlinear Spectroscopy (LENS), Via N. Carrara 1, Sesto Fiorentino, 50019, Italy.
Nat Commun. 2024 Jun 6;15(1):4831. doi: 10.1038/s41467-024-47759-7.
Arrays of Josephson junctions are at the forefront of research on quantum circuitry for quantum computing, simulation, and metrology. They provide a testing bed for exploring a variety of fundamental physical effects where macroscopic phase coherence, nonlinearities, and dissipative mechanisms compete. Here we realize finite-circulation states in an atomtronic Josephson junction necklace, consisting of a tunable array of tunneling links in a ring-shaped superfluid. We study the stability diagram of the atomic flow by tuning both the circulation and the number of junctions. We predict theoretically and demonstrate experimentally that the atomic circuit withstands higher circulations (corresponding to higher critical currents) by increasing the number of Josephson links. The increased stability contrasts with the trend of the superfluid fraction - quantified by Leggett's criterion - which instead decreases with the number of junctions and the corresponding density depletion. Our results demonstrate atomic superfluids in mesoscopic structured ring potentials as excellent candidates for atomtronics applications, with prospects towards the observation of non-trivial macroscopic superpositions of current states.
约瑟夫森结阵列处于量子计算、模拟和计量学量子电路研究的前沿。它们为探索各种基本物理效应提供了一个试验平台，在这些效应中，宏观相位相干、非线性和耗散机制相互竞争。在这里，我们在原子超流约瑟夫森结项链中实现了有限环流状态，该项链由环形超流体中可调谐的隧穿链路阵列组成。我们通过调节环流和结的数量来研究原子流的稳定性图。我们从理论上预测并通过实验证明，通过增加约瑟夫森链路的数量，原子电路能够承受更高的环流（对应于更高的临界电流）。增加的稳定性与由莱格特准则量化的超流分数的趋势形成对比，超流分数反而随着结的数量和相应的密度耗尽而降低。我们的结果表明，介观结构环形势中的原子超流体是原子电子学应用的优秀候选者，有望观察到电流状态的非平凡宏观叠加。
