NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa, Italy.
Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 OFS, UK.
Nat Commun. 2017 Apr 12;8:14984. doi: 10.1038/ncomms14984.
The Josephson effect is a fundamental quantum phenomenon where a dissipationless supercurrent is introduced in a weak link between two superconducting electrodes by Andreev reflections. The physical details and topology of the junction drastically modify the properties of the supercurrent and a strong enhancement of the critical supercurrent is expected to occur when the topology of the junction allows an emergence of Majorana bound states. Here we report charge transport measurements in mesoscopic Josephson junctions formed by InAs nanowires and Ti/Al superconducting leads. Our main observation is a colossal enhancement of the critical supercurrent induced by an external magnetic field applied perpendicular to the substrate. This striking and anomalous supercurrent enhancement cannot be described by any known conventional phenomenon of Josephson junctions. We consider these results in the context of topological superconductivity, and show that the observed critical supercurrent enhancement is compatible with a magnetic field-induced topological transition.
约瑟夫森效应是一种基本的量子现象，通过安德烈夫反射在两个超导电极之间的弱连接中引入无耗散超导电流。结的物理细节和拓扑结构极大地改变了超导电流的性质，当结的拓扑结构允许出现马约拉纳束缚态时，预计会出现临界超导电流的强烈增强。在这里，我们报告了由 InAs 纳米线和 Ti/Al 超导引线形成的介观约瑟夫森结中的电荷输运测量。我们的主要观察结果是，垂直于衬底施加的外磁场引起的临界超导电流的巨大增强。这种显著的反常超导电流增强不能用任何已知的约瑟夫森结的常规现象来描述。我们在拓扑超导的背景下考虑这些结果，并表明观察到的临界超导电流增强与磁场诱导的拓扑转变兼容。
