Manipulating Majorana bound states in S-TI-S Josephson junction networks: braiding, fusion, and parity dynamics

非技术摘要：该奖项结合了实验凝聚态物理和量子信息科学研究，旨在了解一类新发现的材料，并开发将它们整合到用于量子计算的先进电子设备中的方案。重点是拓扑材料，其性质取决于其电子结构的拓扑或几何，使新的电子态能够以独特的方式携带和控制电流。制造和测量一系列先进的混合器件，将这些拓扑材料与超导体集成在一起，将使人们能够探索这种方法的能力和局限性，这种方法被预测将展示新的物理现象和电子性质。除了它们的科学价值外，这些独特的材料还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，信息存储在量子状态中，不受环境的有害影响，这是拓扑设备的一个独特特征，有可能大幅扩展大型计算机的速度和能力。通过这个项目可能产生的新的科学和应用，这个研究计划使不同的博士后研究人员、研究生和本科生接触到与新材料和现象的开发和应用相关的科学问题和实验技术。在材料科学和器件物理的界面上的这种培训已经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：在混合超导体-拓扑绝缘体系统中，已经预测到令人兴奋的新现象，其中对关联产生有效的复杂的超导序参数，表现为手征边缘态，拓扑保护的表面态，以及作为它们自己的反粒子的奇异激发的Majorana费米子。这个项目的重点是核化这些奇异的激发，并以可控的方式操纵它们，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它们独特的非阿贝尔统计，并开发功能方法来成像、操作、读出编码其关键相位信息的宇称，并编织它们执行逻辑运算，所有这些关键步骤都是理解这些新状态的基本物理并为量子信息处理、量子计量学和量子模拟/计算创造技术的关键步骤。主要实验分为两类：(1)研究和表征S-TI-S约瑟夫森结中Majorana态的宇称动力学并确定影响它的材料和器件属性-这包括观察和表征宇称涨落的实验，约瑟夫森相动力学和宇称跃迁相互作用的建模，以及提高宇称寿命的方法，(2)在S-TI-S平台上开发用于编织、融合和读出Majorana模的方案，这是实施方案所需的所有重要能力。拓扑物理领域是一个非常新的领域，世界各地的研究人员刚刚开始集体探索材料、测量和理论概念，这些概念对于理解Majorana费米子以及如何在电子电路中利用它们将是重要的。该项目探索了这一领域中尚未解决的关键问题，以及在理解奇异的Majorana费米子的性质和在功能超导电路中实施它们方面取得重大进展的途径。该奖项反映了NSF的法定使命，通过使用基金会的学术价值和更广泛的影响审查标准进行评估，被认为是值得支持的。

Non-Technical Abstract:This award combines experimental condensed matter physics and quantum information science research aimed at understanding a newly-discovered class of materials and developing schemes for incorporating them into advanced electronic devices for quantum computing. The focus is on topological materials whose properties depend on the topology, or geometry, of their electronic structure, enabling novel electronic states that can carry and control currents in unique ways. Fabricating and measuring a series of advanced hybrid devices that integrate these topological materials with superconductors will enable exploration of the capabilities and limitations of this approach that has been predicted to exhibit new physical phenomena and electronic properties. In addition to their scientific interest, these unique materials can be implemented in electronic circuits to create a new type of computer platform in which the information is stored in quantum states protected from the detrimental effects of the environment, a unique feature of topological devices that has the potential to extend dramatically the speed and capability of large-scale computers. Through 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 two categories: (1) investigation and characterization of the parity dynamics of Majorana states in S-TI-S Josephson junctions and determine the materials and device properties that affect it --- this includes experiments to observe and characterize parity fluctuations, modeling of the interplay of Josephson phase dynamics and parity transitions, and ways to improve parity lifetimes, (2) development of schemes for braiding, fusion, and parity readout of Majorana modes in the S-TI-S platform, all important capabilities required to implement scheme. 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.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.