Sato Yosuke, Ueda Kento, Takeshige Yuusuke, Kamata Hiroshi, Li Kan, Samuelson Lars, Xu H Q, Matsuo Sadashige, Tarucha Seigo
Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Phys Rev Lett. 2022 May 20;128(20):207001. doi: 10.1103/PhysRevLett.128.207001.
The Josephson junction of a strong spin-orbit material under a magnetic field is a promising Majorana fermion candidate. Supercurrent enhancement by a magnetic field has been observed in the InAs nanowire Josephson junctions and assigned to a topological transition. In this work we observe a similar phenomenon but discuss the nontopological origin by considering the trapping of quasiparticles by vortices that penetrate the superconductor under a finite magnetic field. This assignment is supported by the observed hysteresis of the switching current when sweeping up and down the magnetic field. Our experiment shows the importance of quasiparticles in superconducting devices with a magnetic field, which can provide important insights for the design of qubits using superconductors.
在磁场下强自旋轨道材料的约瑟夫森结是一种很有前景的马约拉纳费米子候选体系。在砷化铟纳米线约瑟夫森结中已观测到磁场导致的超电流增强，并将其归因于拓扑相变。在这项工作中，我们观测到了类似现象，但通过考虑在有限磁场下穿透超导体的涡旋对准粒子的俘获来讨论非拓扑起源。当磁场上下扫描时开关电流的滞后现象支持了这一归因。我们的实验表明了准粒子在有磁场的超导器件中的重要性，这可为利用超导体设计量子比特提供重要见解。
