EAGER: BRAIDING: Materials to enable voltage-gateable Majorana systems in silicon using top-down fabrication techniques

非技术摘要：现代最先进的单芯片处理器进入我们的日常电子设备，如手机，包含数十亿个晶体管。自1971年以来，这一数字一直在翻一番，大约每两年一次，遵循摩尔定律。我们现在正处于极限产能的门槛，这促使人们寻找新的集成电路。这个迫切的项目是一项新颖的探索性工作，其最终目标是创造和操纵硅基超导异质结构，以便为拓扑量子晶体管提供基础。这个项目建立在最近的实验进展的基础上，证明了掺杂的共价半导体中存在超导电性，使用硅是因为这种材料是现代微电子工业中最常见的半导体，所以具有吸引力。因此，探索一种方法，在这种方法中，可以将高度可扩展的半导体门控制整合到超导设备中，用于量子计算，这是一种激励人心的方法。这可以通过使用金属顶门来定义超导半导体量子电路来实现，这一技术类似于目前大规模微电子中使用的技术。在某些条件下，这些电路具有由Majorana模式编码的非常特殊的属性，Majorana模式是能够实现受拓扑原理保护的操作的激励。因此，这些系统对各种消相干源具有潜在的高度抵抗力，这是非拓扑量子处理器的主要问题。实现拓扑量子计算是一个巨大的挑战，具有潜在的社会变革意义。该项目的工作将通过培训研究生和其他初级科学家在量子信息、纳米制造、量子比特和材料的表征、理论模拟和计算以及实验设计和实践方面对人力资源的开发产生影响。技术摘要：这个渴望新工作的项目是探索一种方法，即高度可扩展的半导体门控制可以结合到用于量子计算的超导器件中。这项拟议的研究旨在利用金属顶门来表征和开发支持Majorana费米子态的超导半导体量子电路，这一技术类似于目前大规模微电子中使用的技术。该项目在威斯康星大学麦迪逊分校物理系的实验和理论之间取得了平衡。实验目标包括：(I)开发富含镓的硅中可光刻图案和可电压门控的超导层；(Ii)实现全硅超导半导体约瑟夫森场效应晶体管；(Iii)测量约瑟夫森结的各种输运特性，如电流-电压特性、电流-相位关系和夫琅和费干涉图案。理论上的努力包括探索超导硅通道内的可形成图案的微磁体配置，从而能够形成健壮的Majorana模式。理论工作还包括在存在掺杂诱导的不均匀时计算硅镓超导体的基本参数，对所提出的器件的输运特性进行建模，以及根据实验上可控制的真实参数来确定包含拓扑非平凡状态的相图。

Non-technical Abstract: Modern state of the art single-chip processors that go into our everyday electronic devices, such as cellphones, contain billions of transistors. This number has been doubling ever since 1971 approximately every two years following the trend of Moore's law. Weare now at the threshold of ultimate capacity, which motivates the search for new integrated circuits. This EAGER project is for novel exploratory work whose eventual goal is to create and manipulate silicon-based superconducting heterostructures in order to provide a foundation for topological quantum transistors. This project builds on recent experimental progress demonstrating that superconductivity arises in doped covalent semiconductors, and the use of Si is attractive because this material is the most common semiconductor in the modern microelectronics industry. It is therefore motivating to explore an approach where highly scalable gate control of semiconductors can be incorporated into superconducting devices for quantum computing purposes. This could be achieved by defining superconducting-semiconductor quantum circuits using metal top gates, a technology similar to that currently employed in large scale microelectronics. Under certain conditions these circuits have very special properties encoded by Majorana modes, which are excitations that enable operations that are protected by topological principles. Thus, these systems are potentially highly resistant to various sources ofdecoherence, which is the main problem in non-topological quantum processors. Implementing topological quantum computation is a grand challenge with potentially transformative societal implications. The work on the project will have an impact on development of human resources by training of graduate students and other junior scientists in quantum information, nanofabrication, characterization of qubits and materials, theoretical simulation and calculation, and experimental design and practice.Technical Abstract: This EAGER project is for novel work to explore an approach where highly scalable gate control of semiconductors can be incorporated into superconducting devices for quantum computing purposes. The proposed research aims to characterize and develop superconducting semiconductor quantum circuits supporting Majorana fermion states using metal top gates, a technology similar to that currently employed in large-scale microelectronics. The project is balanced between the experiment and theory in the Physics Department of the University of Wisconsin-Madison. Experimental goals include: (i) development of lithographically patternable and voltage-gateable superconducting layers in silicon enriched by gallium; (ii) realization of all-silicon superconducting semiconductor Josephson field effect transistors; (iii) measurements of various transport characteristics of Josephson junctions such as current voltage characteristics, current-phase relationships, and Fraunhofer interference patterns. Theoretical efforts include exploration of patternable micromagnet configurations within the superconducting silicon channel that enable formation of robust Majorana modes. Theory work additionally includes computation of essential parameters for the silicon-gallium superconductor in the presence of doping-induced inhomogeneities, modeling transport characteristics of proposed devices, and determination of the phase diagram that hosts topologically nontrivial states in terms of realistic parameters that are controllable experimentally.