Majorana Fermions

目前，围绕拓扑超导网络中的马约拉纳零模（MZM）的研究非常令人兴奋：这是实现全固态量子处理器的一条可能的技术路线。最近，关于半导体纳米线的重要工作为MZM的存在提供了初步证据，理论预测MZM是可以用于量子处理的稳健量子态，但与其他演示量子技术不同的是，MZM有可能在熟悉的固态技术中实现。然而，现在有相当大的争论，在文献中的确定性，这些意见，和必要的扩展到更可利用的平面（2DEG）技术是难以捉摸的。状态发生在具有强自旋轨道耦合（SOC）的一维（1D）半导体与邻近超导体之间的界面处。通过电学研究，本项目将探索最先进的基于锑化铟（InSb）的量子阱异质结构，该异质结构具有所有化合物半导体中最大的SOC，并研究与超导材料界面处的MZM形成。我们将利用我们在谢菲尔德大学的长期合作伙伴生长的材料（EPSRC英国国家外延设施），与沃里克大学，以及一个新的合作与克里斯Palmstrom集团在加州大学圣巴巴拉（UCSB）。材料将在表面上生长超导铝，或在研究不同磺化表面制备的同时沉积超导材料，以实现超导体与半导体界面的不同能带对准。该项目将涉及在化合物半导体研究所（ICS）洁净室设施内使用照片和电子束光刻进行器件制造，与工艺工程师一起工作，以现有的工艺技术为基础，研究半导体材料中的邻近感应超导，低泄漏表面门控，以创建隧道势垒，并最终明确观察马约拉纳费米子。这些器械将在低温（可能低至15 mK）下进行高灵敏度电导率测量，并在适当情况下进行高磁场测量。

There is currently great excitement surrounding the investigation of Majorana zero modes (MZMs) in topological superconducting networks: A possible technology route to an all solid state quantum processor. Recently, significant work on semiconductor nanowires has offered tentative evidence for the existence of MZMs, which are predicted by theory to be robust quantum states that can be exploited for quantum processing, and yet unlike other demonstrator quantum technologies are potentially realisable in familiar solid state technology. However there is now considerable debate in the literature about the certainty of these observations, and the necessary extension to more exploitable planar (2DEG) technology is elusive. States occur at the interface between a one-dimensional (1D) semiconductor that has strong spin-orbit coupling (SOC), and a proximity superconductor. Through electrical study this project will explore state-of-the-art Indium Antimonide (InSb) based quantum well heterostructures that have the largest SOC of all the compound semiconductors, and investigate MZM formation at the interface with superconducting material.We will exploit material grown at our long standing collaborators at the University of Sheffield (EPSRC UK National epitaxy facility), together with Warwick University, and a new collaboration with the group of Chris Palmstrom at the University of California Santa Barbara (UCSB). Material will be both grown with superconducting Al on the surface, or have superconducting material deposited whilst investigating different sulfonation surface preparations to achieve different band alignments of the superconductor to semiconductor interface.The project will involve device fabrication within the Institute for Compound Semiconductors (ICS) cleanroom facility, using both photo and electron beam lithography, working alongside process engineers to build on existing process technology to investigate proximity induced superconduction in the semiconductor material, low leakage surface gating to enable the creation of tunnel barriers, and ultimately the unambiguous observation of Majorana Fermions. These devices will be measured at low temperature (potentially down to 15mK) with high sensitivity electrical conductivity measurement, and where appropriate high magnetic field.