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arXiv 1902.07804cond-mat.mes-hallcond-mat.supr-con
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InAs纳米线约瑟夫森结的电流-相位关系:从相互作用到多模区

Current-phase relations of InAs nanowire Josephson junctions: from interacting to multi-mode regimes

Sean Hart, Zheng Cui, Gerbold Menard, Mingtang Deng, Andrey Antipov, Roman M. Lutchyn, Peter Krogstrup, Charles M. Marcus, Kathryn A. Moler

摘要:

具有超导引线的门可调谐超导体纳米线形成奇异的约瑟夫森结,这是两种类型的量子比特的非常理想的平台:具有拓扑超导性的量子比特(马约拉纳量子比特)和基于可调谐非谐性的量子比特(门控量子比特)。然而,控制它们的行为需要了解它们的静电环境和电子结构。在这里,我们研究门InAs纳米线与外延铝壳。通过测量电流-相位关系(CPR),并将其与分析和数值计算进行比较,我们表明,我们可以调整模式的数量,确定每个模式的透明度,并调整到电子-电子相互作用明显的制度,表明存在一个量子点。考虑到静电和几何效应,我们进行微观自洽薛定谔-泊松数值模拟,揭示了结中的Andreev态的能谱以及它们的空间分布。我们的工作系统地展示了器件几何形状,栅极电压和相位偏置对模式行为的影响,为正在进行的实验工作和预测器件设计提供了新的见解。

英文摘要:

Gate-tunable semiconductor-superconductor nanowires with superconducting leads form exotic Josephson junctions that are a highly desirable platform for two types of qubits: those with topological superconductivity (Majorana qubits) and those based on tunable anharmonicity (gatemon qubits). Controlling their behavior, however, requires understanding their electrostatic environment and electronic structure. Here we study gated InAs nanowires with epitaxial aluminum shells. By measuring current-phase relations (CPR) and comparing them with analytical and numerical calculations, we show that we can tune the number of modes, determine the transparency of each mode, and tune into regimes in which electron-electron interactions are apparent, indicating the presence of a quantum dot. To take into account electrostatic and geometrical effects, we perform microscopic self-consistent Schrodinger-Poisson numerical simulations, revealing the energy spectrum of Andreev states in the junction as well as their spatial distribution. Our work systematically demonstrates the effect of device geometry, gate voltage and phase bias on mode behavior, providing new insights into ongoing experimental efforts and predictive device design.

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