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

摘要：现代最先进的单芯片处理器应用于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，这个数字大约每两年翻一番，遵循摩尔定律的趋势。我们现在正处于极限容量的门槛，这促使我们寻找新的集成电路。这个EAGER项目是一个新颖的探索性工作，其最终目标是创建和操纵硅基超导异质结构，为拓扑量子晶体管提供基础。该项目建立在最近的实验进展的基础上，证明了超导性出现在掺杂共价半导体中，硅的使用是有吸引力的，因为这种材料是现代微电子工业中最常见的半导体。因此，探索一种方法是激励的，这种方法可以将半导体的高度可扩展门控制集成到超导器件中，用于量子计算目的。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，这种技术类似于目前大规模微电子技术中使用的技术。在某些条件下，这些电路具有由马约拉纳模式编码的非常特殊的性质，这是一种激励，使操作受到拓扑原理的保护。因此，这些系统具有潜在的高度抵抗各种退相干源的能力，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项具有潜在变革性社会影响的巨大挑战。该项目的工作将通过培养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的人力资源发展产生影响。技术摘要：这个EAGER项目旨在探索一种新的方法，该方法可以将半导体的高度可扩展门控制集成到用于量子计算目的的超导器件中。提出的研究旨在表征和开发超导半导体量子电路，使用金属顶门支持马约拉纳费米子态，这是一种类似于目前在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进行平衡。实验目标包括：(i)在富含镓的硅中开发可光刻图案化和可电压门控的超导层；（二）全硅超导半导体约瑟夫森场效应晶体管的实现；（iii）测量约瑟夫森结的各种输运特性，如电流电压特性、电流相位关系和弗劳恩霍夫干涉图。理论上的努力包括在超导硅通道中探索可模式化的微磁体结构，从而形成稳健的马约拉纳模式。理论工作还包括在掺杂诱导非均匀性存在的情况下计算硅镓超导体的基本参数，模拟所提出器件的输运特性，以及根据实验可控的实际参数确定承载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.