Creating, manipulating, and detecting Majorana fermion states in hybrid superconductor-topological insulator Josephson devices

摘要：该奖项支持旨在理解新发现的一类材料和实现未来先进电子设备的实验研究。这项研究的重点是拓扑材料，之所以称为“拓扑”，是因为它们的性质主要取决于其电子结构的拓扑或几何形状。通过制造和测量一系列将这些拓扑材料与超导体结合在一起的先进设备，将探索这一快速新兴领域的能力和局限性。除了它们可能的技术应用之外，这些独特的材料可以在电子电路中实现，以创建一种新型的计算机平台，在这种平台中，信息被存储在免受环境有害影响的状态下。这是拓扑设备的一个独特特征，它有可能极大地扩展大型计算机的速度和能力。除了该项目可能产生的新科学和应用之外，该研究项目还为博士后研究人员、研究生和本科生提供了与新材料和新现象的开发和应用相关的科学问题和实验技术。这种材料科学和器件物理结合的培训已被证明在高科技领域的科学家和工程师的职业生涯中是非常有效的。技术摘要：在超导体-拓扑绝缘体的杂化系统中，预计会出现令人兴奋的新现象，在这种系统中，对相关诱导出一个有效的复杂超导序参量，表现出手性边缘态、拓扑保护表面态和马约拉纳费米子（它们本身就是反粒子的奇异激发）。本项目重点研究如何使这些奇异的激励成核，并以可控的方式对其进行操纵，以验证它们的存在，并探索它们的稳定性和动力学。一系列特定的实验旨在揭示其独特的非阿贝尔统计，并开发功能方法来成像，操纵，读取编码其关键相位信息的宇称，并将其编织以执行逻辑运算，所有关键步骤都是为了理解这些新状态的潜在物理，并为量子信息处理，量子计量和量子模拟/计算技术制作技术。关键实验分为四个相互交织的类别：(1)通过光谱和成像绘制马约拉纳费米子的位置，寻找作为这些独特状态特征的间隙中的零能态；(2)通过相敏Josephson干涉法探测马约拉纳费米子的动力学，寻找作为马约拉纳费米子状态特征特征的周期性电流-相位关系；(3)操纵和检测马约拉纳费米子的奇偶性。探索使用约瑟夫森电子学通过直接测量超电流的特定分量来测量奇偶性的方法，以及(4)验证和使用马约拉纳费米子的非阿贝尔统计量，这是马约拉纳费米子模式最具特色和最有趣的方面，也是使它们对量子信息处理和计算具有高度吸引力的特性。拓扑物理学是一个非常新的领域，全世界的研究人员都刚刚开始探索材料、测量和理论概念，这些对于理解马约拉纳费米子以及如何在电子电路中利用它们非常重要。本项目探索了该领域尚未解决的关键问题，以及在理解外来马约拉纳费米子的性质并将其应用于功能超导体电路方面取得重大进展的途径。它还提供了在该领域的科学和技术方面培训学生的机会，预计在未来几年将有所增长。

Non-Technical Abstract: This award supports experimental research aimed at understanding a newly-discovered class of materials and enabling future advanced electronic devices. The research focuses on topological materials, called "topological" because their properties depends primarily on the topology, or geometry, of their electronic structure. By fabricating and measuring a series of advanced devices that integrate these topological materials with superconductors, the capabilities and limitations of this rapidly emerging field will be explored. In addition to their possible technological applications, these unique materials can be implemented in electronic circuits to create a new type of computer platform in which the information is stored in states protected from the detrimental effects of the environment. This is a unique feature of topological devices that has the potential to extend dramatically the speed and capability of large-scale computers. In addition to the new science and applications that may arise from this project, this research program exposes a diverse cadre of postdoctoral researchers, graduate research students, and undergraduate students to scientific issues and experimental techniques relevant to the development and applications of new materials and phenomena. This training at the interface of materials science and device physics has been demonstrated to be highly effective in launching the careers of scientists and engineers in high technology fields.Technical Abstract: Exciting new phenomena have been predicted to arise in hybrid superconductor-topological insulator systems in which pair correlations induce an effective complex superconducting order parameter exhibiting chiral edge states, topologically-protected surface states, and Majorana fermions, exotic excitations that are their own antiparticles. This project focuses on schemes to nucleate these exotic excitations and manipulate them in controllable ways to verify their existence and explore their stability and dynamics. A series of specific experiments are designed to reveal their unique non-Abelian statistics and to develop functional approaches to image, manipulate, readout the parity that encodes their critical phase information, and braid them to perform logical operations, all critical steps toward understanding the underlying physics of these novel states and crafting a technology for quantum information processing, quantum metrology, and quantum simulation/computing. Key experiments fall into four interwoven categories: (1) mapping the location of Majorana fermions via spectroscopy and imaging, looking for the zero-energy states in the gap that are signatures of these unique states, (2) probing the dynamics of Majorana fermions by phase-sensitive Josephson interferometry, searching for the periodic current-phase relation that is a characteristic signature of the Majorana fermions states, (3) manipulating and detecting the parity of Majorana fermions, exploring ways to measuring the parity via direct measurements of specific components of the supercurrent using Josephson electronics, and (4) verifying and using the non-Abelian statistics of Majorana fermions, the most characteristic and intriguing aspect of Majorana fermion modes and the property that makes them highly attractive for quantum information processing and computing. The field of topological physics is very new and researchers worldwide are collectively just starting to explore the materials, measurements, and theoretical concepts that will be important in achieving an understanding of Majorana fermions and how to exploit them in electronic circuits. This project explores the key unsolved problems in this field and paths for making significant advances in understanding the nature of exotic Majorana fermions and implementing them in functional superconductor circuits. It also provides opportunities to train students in the science and technology of this field that is anticipated to grow in the coming years.