EAGER: BRAIDING: Transport studies of the anyon braiding

摘要：量子计算是近年来备受关注的一个重要研究课题。量子计算的实现是建立在量子比特的产生和操作的基础上的。虽然这个改变范式的想法已经被知道了30多年，但量子计算机的实现仍处于非常早期的阶段。一个主要的挑战是最小化量子退相干，起源于各种因素，如量子系统和环境之间的相互作用。面对这一挑战，一个潜在的解决方案是拓扑量子计算，它利用相干性受到保护的量子比特。本文提出的工作旨在通过研究电荷输运特征来实验实现拓扑量子计算的基础。所提出的工作结合了理论和实验的努力。该结果可能为未来如何控制单个拓扑激励的研究提供直接指导，可能导致拓扑量子计算新量子比特的发展取得突破。该项目的研究将材料科学（纳米材料）、纳米技术、电子学、低温学、理论凝聚态物理和量子信息科学结合起来。此外，面向公众的外展活动，包括石溪大学西蒙斯夏季研究项目和物理与天文学系周五晚上的物理世界讲座。技术摘要：基于任意子准粒子编织的拓扑量子计算概念有可能为量子计算中的退相干挑战提供解决方案。本研究的目的是研究在不需要时间相关控制的情况下，通过一种设置来操纵拓扑状态的可能性，在这种设置中，任意离子激励的编织作为传输过程的一部分自动实现。该装置由一个三点结构组成，其输运特性体现了任意子激发通过点间隧穿的编织统计。在两种材料体系中对该方案进行了研究。1)具有支持分数量子霍尔态和任意带电准粒子的“反点”的2DEG；2)支持Majorana模式的拓扑绝缘体/s波超导异质结。在这两个系统中，源漏电流的测量提供了准粒子任意子统计信息。所提出的工作绕过了对单个拓扑激励进行随时间控制的困难，直接研究了拓扑编织的基础：准粒子交换统计量及其输运签名。了解任意子激发的量子干涉和拓扑编织对任意子统计的影响，是拓扑量子计算的科学基础。本文提出的技术方法将直接回答拓扑编织如何影响电荷输运特性，以及包括温度和无序在内的各种参数如何影响量子相干性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Abstract: Quantum computing has been a major research topic of interest in recent years. The realization of quantum computing is based on creation and manipulation of quantum bits (qubits). While this paradigm-changing idea has been known for over 30 years, the realization of quantum computers is still at the very early stage. A major challenge is to minimize quantum decoherence, originated from various factors such as the interaction between a quantum system and the environment. Towards this challenge, a potential solution is topological quantum computing which utilizes qubits whose coherence is protected. The proposed work here aims to experimentally realize the very foundation of topological quantum computing, by studying the charge transport signatures. The proposed work combines theoretical and experimental efforts. The outcome may provide direct guidance for future research on how to control individual topological excitations, potentially leading to breakthroughs in the development of novel qubits for topological quantum computing. The proposed research brings a combination of material science (nanomaterials), nanotechnology, electronics, cryogenics, theoretical condensed matter physics and quantum information science to students involved in the project. In addition, outreach activities, including Stony Brook University Simons summer research program and Department of Physics and Astronomy's World of Physics Friday evening lectures will be carried out to the general public. Technical Abstract: The concept of topological quantum computing, based on anyonic quasiparticle braiding, potentially offers a solution to the decoherence challenge in quantum computing. The objective of the proposed research is to investigate the possibility to manipulate the topological states with a set-up in which the braiding of anyonic excitations is achieved automatically as a part of the transport process without the need for the time-dependent control. The set-up consists of a triple-dot structure, whose transport characteristics manifest the braiding statistics of the anyonic excitation through inter-dot tunneling. Such scheme is studied in two types of material systems. 1) 2DEG with 'antidots' which support fractional quantum Hall states and anyonic charged quasiparticles; 2) topological insulator/s-wave superconductor heterojunctions which support Majorana modes. In both systems, measurements of the source-drain current provide information on the quasiparticle anyon statistics. The proposed work bypasses the difficulty in time-dependent controlling over the individual topological excitations and directly investigate the basis for the topological braiding: the quasiparticle exchange statistics and its transport signature. Understanding the quantum interference of the anyonic excitations and the impact of topological braiding on the anyonic statistics lays the scientific foundation of topological quantum computing. The technical approach proposed here will provide direct answers to how topological braiding impacts on the charge transport characteristics, and how various parameters including temperature and disorder affect quantum coherence.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.