QuTech, Delft University of Technology , 2600 GA Delft, The Netherlands.
Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands.
Nano Lett. 2017 Apr 12;17(4):2690-2696. doi: 10.1021/acs.nanolett.7b00540. Epub 2017 Apr 3.
Topological superconductivity is a state of matter that can host Majorana modes, the building blocks of a topological quantum computer. Many experimental platforms predicted to show such a topological state rely on proximity-induced superconductivity. However, accessing the topological properties requires an induced hard superconducting gap, which is challenging to achieve for most material systems. We have systematically studied how the interface between an InSb semiconductor nanowire and a NbTiN superconductor affects the induced superconducting properties. Step by step, we improve the homogeneity of the interface while ensuring a barrier-free electrical contact to the superconductor and obtain a hard gap in the InSb nanowire. The magnetic field stability of NbTiN allows the InSb nanowire to maintain a hard gap and a supercurrent in the presence of magnetic fields (∼0.5 T), a requirement for topological superconductivity in one-dimensional systems. Our study provides a guideline to induce superconductivity in various experimental platforms such as semiconductor nanowires, two-dimensional electron gases, and topological insulators and holds relevance for topological superconductivity and quantum computation.
拓扑超导是一种物质状态，能够承载马约拉纳模式，而马约拉纳模式是拓扑量子计算机的构建模块。许多被预测可以展示这种拓扑状态的实验平台都依赖于近邻诱导超导性。然而，要获得拓扑性质需要一个诱导的硬超导能隙，这对于大多数材料系统来说都是具有挑战性的。我们已经系统地研究了 InSb 半导体纳米线和 NbTiN 超导体之间的界面如何影响诱导超导性质。我们逐步提高界面的均匀性，同时确保与超导体的无阻碍电接触，并在 InSb 纳米线中获得硬能隙。NbTiN 的磁场稳定性允许 InSb 纳米线在磁场（约 0.5T）存在的情况下保持硬能隙和超导电流，这是一维系统中拓扑超导的要求。我们的研究为在半导体纳米线、二维电子气和拓扑绝缘体等各种实验平台中诱导超导提供了指导，并与拓扑超导和量子计算相关。
