基于二维半导体面内异质结构建拓扑量子计算器件的实验探索

构造强自旋轨道耦合的低维半导体与超导材料的异质结是当前实现马约拉纳零能模的主流方案之一。然而，由于界面上多种物理机制和缺陷效应共同作用带来的复杂性，在马约拉纳零能模的判据、零能模的稳定性等方面，目前基于非原位器件制备方法的实验研究仍然存在诸多问题。本项目拟利用面内分子束外延方法，在超高真空环境中原位生长IV-VI族或过渡金属硫族化合物二维半导体面内异质结，进而制备原子级平整的纳米线结构并得到一维金属态，并在此基础上进一步原位外延二维超导材料，通过超导近邻效应实现马约拉纳零能模。同时，本项目将利用原子级精确的扫描隧道显微学方法，结合矢量磁场和原位电场调控等技术对异质结中的局域电子结构进行表征和调控，以寻求对马约拉纳零能模的可靠判据。本项目将力求得到一套高可靠性和可重复性的马约拉纳零能模制备和表征方法，从而为未来基于二维材料面内异质结设计拓扑量子比特的技术路线奠定基础。

Building the heterostructures between a low-dimensional semiconductor with strong spin-orbital coupling and a superconductor is one of the mainstream strategies for realizing Majorana zero modes (MZM) nowadays. However, because of the complexity introduced by the multiple physical mechanisms happening at the interface and possible influence of defects, the current experiments based on ex situ device fabrication are still suffering from many problems in the criteria of MZM, the stability of MZM, etc. In this proposal, we plan to grow the in-plane heterostructures between two-dimensional semiconductors, such as group-IV monochalcogenides or transition metal dichalcogenides, by the in-plane molecular beam epitaxy technique, from which atomically sharp nanowire structures with one-dimensional metallic states can be obtained. By the further in situ epitaxy of two-dimensional superconducting materials, MZMs are expected to form due to superconducting proximity effect. Furthermore, we will characterize and tune the MZM states by applying atomically precise scanning tunneling microscopy methods with tunable vector magnetic fields and electric fields, in order to pursue reliable criteria for distinguishing MZMs from complex electronic states. This program will offer highly repeatable and robust methods for fabricating and characterizing MZMs for the future design of topological qubits based on two-dimensional material in-plane heterostructures.