Zero energy modes in vortex cores: Spectroscopy and Majorana carousel braiding

涡核中的零能量模式：光谱学和马约拉纳旋转木马编织

• 批准号: 2104757
• 负责人: Alexey Bezryadin
• 金额: $ 35.42万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104757&HistoricalAwards=false
• 关键词: Zero; energy; modes; vortex; cores

Nontechnical Abstract: Quantum computers are expected to enable transformative advances in information technology, quantum chemistry, secure communications, material modeling, and in many other applications. Aluminum-based superconducting qubits demonstrate promising characteristics as building blocks for quantum computers. Yet, even with the recent impressive advances in this field, building a fully functional and practically useful quantum computer is still beyond reach, since existing qubits loose quantum information very quickly. The problem can be solved if the theoretically predicted, so-called non-Abelian excitations can be realized in solid-state nanoscale devices. Such hypothetical non-Abelian excitations have a useful and very counterintuitive property. Even though they are identical, if two of them exchange places, they collectively evolve into new quantum states. This property can be used to perform noise-proof quantum computation, which is protected from environmental interference. The PI and the research team are developing nanoscale electronic devices in which non-Abelian phenomena can be demonstrated. The approach is motivated by recent theoretical results suggesting how these excitations can be effectively isolated from perturbations caused the environment. The research team uses traditional superconducting qubits, microwave technology, and quantum tunneling contacts to perform energy measurements and to uncover the hypothetical non-Abelian Majorana modes. A special Corbino disk geometry exploits quantum mechanical behavior of vortices containing these exotic excitations. This research offers modern physics training for graduate and undergraduate students and provides extensive mentoring to the next generation of scientists and engineers.Technical Abstract: Many theoretical models have been suggested in which Majorana zero modes are used for topologically protected quantum computation. Nevertheless, their key property, namely the non-Abelian physics, has not yet been demonstrated experimentally. The traditional approach to study Majorana modes is to employ semiconductor nanowires coupled to superconductors. The present project explores a different route. The PI and his team study Majorana modes in the cores of superconducting vortices in topological superconductors. The goal is to isolate Majorana modes from ordinary electronic states and to demonstrate the hypothetical non-Abelian effects, which, if found, will help to solve key problems of quantum information technology. The PI and the research team perform microwave and tunneling experiments to measure the discrete spectrum of the topological vortex cores. An important obstacle in such experiments is the large number of low-energy non-topological excitations present within vortices. Such electrons can mix with the Majorana modes, making non-Abelian physics undetectable. The research group uses recent theoretical models to design and study novel devices in which the vortex is trapped within a superconducting sample having a circular hole with a topological superconductor or a topological insulator at the bottom. In such devices, the Majorana energy gap is predicted to be sufficiently large to isolate the Majorana modes from non-topological excitations. The research team is also developing the next generation of such devices, in which vortices can move following circular trajectories in Corbino-geometry devices. Such circular motion is used to exchange positions of Majorana modes and to induce nontrivial changes in the quantum state of the system. The Majorana modes are probed and controlled using ordinary qubits.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.

非技术摘要：量子计算机有望在信息技术，量子化学，安全通信，材料建模以及许多其他应用中的变革性进步。基于铝制的超导码头表现出有希望的特征作为量子计算机的基础。然而，即使在该领域的最新进展中，构建功能齐全且实际上有用的量子计算机仍然无法触及，因为现有的量子比特很快就会放松量子信息。如果可以在固态纳米级设备中实现理论上预测的，所谓的非亚洲激发，则可以解决该问题。这种假设的非亚洲激发具有有用且非常违反直觉的特性。即使它们是相同的，如果其中两个交换位置，它们共同演变为新的量子状态。该属性可用于执行防噪量子计算，该计算免受环境干扰。 PI和研究团队正在开发纳米级电子设备，其中可以证明非亚伯现象。该方法是由最近的理论结果激发的，表明如何有效地从扰动中隔离这些激发。研究小组使用传统的超导量子台，微波技术和量子隧道触点来执行能量测量并揭示假设的非亚伯利亚主要主体模式。一种特殊的Corbino磁盘几何形状利用了包含这些异国激发的涡流的量子机械行为。这项研究为研究生和本科生提供了现代的物理培训，并为下一代科学家和工程师提供广泛的指导。技术摘要：已经提出了许多理论模型，其中Majorana零模式用于拓拓保护的量子计算。然而，他们的关键特性，即非亚伯来物理学，尚未在实验中证明。研究主要模式的传统方法是使用与超导体结合的半导体纳米线。本项目探索了另一条路线。 PI和他的团队在拓扑超导体中的超导涡流核心中学习Majorana模式。目的是将Majorana模式与普通电子状态隔离开来，并证明假设的非亚洲效应，如果发现该效应将有助于解决量子信息技术的关键问题。 PI和研究团队执行微波和隧道实验，以测量拓扑涡流核的离散光谱。在此类实验中，重要的障碍是涡流中存在大量的低能性非原始激发。这样的电子可以与主要模式混合，从而使非亚伯物理学无法检测到。研究小组使用最新的理论模型来设计和研究新型设备，其中涡流被困在具有圆形孔的超导样本中，底部具有拓扑超导体或拓扑绝缘子。在这样的设备中，预测Majorana能量差距足够大，可以将Majoraana模式与非人种激励分离。研究团队还正在开发下一代此类设备，在这种设备中，涡流可以在Corbino几何设备中循环轨迹移动。这种循环运动用于交换主要模式的位置，并诱导系统量子状态的非平凡变化。 Majoraana模式是使用普通Qubits进行探测和控制的。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评论标准来评估值得支持的。