EAGER: BRAIDING: Majorana modes in monolayer topological insulator WTe2

渴望：编织：单层拓扑绝缘体 WTe2 中的马约拉纳模式

• 批准号: 1836697
• 负责人: David Cobden
• 金额: $ 29.9万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-15 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1836697&HistoricalAwards=false
• 关键词: EAGER; BRAIDING; Majorana; modes; monolayer

Nontechnical Abstract: Finding alternative paths to quantum computing is paramount at this time, and current approaches face many hurdles. The biggest is decoherence of the qubits, meaning that the quantum information content decays exponentially with time. In principle, decoherence can be avoided using "topological protection". The only realistic known scheme for topological protection is based on creating the qubits from so-called Majorana modes, which are peculiar states that occur at the ends of certain types of quantum wires. One way to make Majoranas is using the special quantum wire that exists at the edge of a topological insulator. The PI, an experimentalist, recently discovered the first natural monolayer two-dimensional (2D) topological insulator, suggesting the possibility to create and manipulate Majoranas in 2D materials. The co-PI is a theorist and expert on topological phenomena; in this project they collaborate to find the simplest way to create and detect Majoranas in this system. The work supports graduate students in topical interdisciplinary work where theory and experiment go hand in hand, and which could conceivably give birth to the next information revolution. The project forms a bridge between the University of Washington, which has a leading research effort in 2D materials, and local industry (including Microsoft) which is investing heavily in applications of quantum computers.Technical: This project aims to establish the viability of the 2D materials platform for creating Majorana zero modes that could be used for topological quantum processing. The team employs monolayer WTe2 as a 2D topological insulator, combined with a 2D superconductor (NbSe2 or FeSe) and a 2D magnet (CrI3 or CrBr3). These materials are stacked into a van der Waals heterostructure along with electrical contacts and tunnel barriers. At the point where the three materials meet a Majorana mode may appear at low temperatures and can be probed by tunneling measurements. This 2D platform offers advantages compared with other Majorana systems including that no magnetic field is required to produce the helical mode, and the possibility to avoid delicate tuning of the chemical potential. The complexity of the many-electron and topological physics involved, and the novelty of the system, calls for close cooperation between experiment and theory. Specific goals are to induce and understand a superconducting proximity gap in the helical edge of WTe2, and to design and test the simplest 2D possible heterostructure devices in which Majoranas may occur and be detected.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：此时寻找量子计算的替代路径至关重要，而当前的方法面临许多障碍。最大的问题是量子位的退相干，这意味着量子信息内容随着时间呈指数衰减。原则上，可以使用“拓扑保护”来避免退相干。唯一现实的已知拓扑保护方案是基于从所谓的马约拉纳模式创建量子位，马约拉纳模式是发生在某些类型的量子线末端的特殊状态。制造马约拉纳的一种方法是使用存在于拓扑绝缘体边缘的特殊量子线。实验学家 PI 最近发现了第一个天然单层二维 (2D) 拓扑绝缘体，这表明了在 2D 材料中创建和操纵马约拉纳的可能性。联合PI是拓扑现象理论家和专家；在这个项目中，他们合作寻找在该系统中创建和检测马约拉纳的最简单方法。这项工作支持研究生进行专题跨学科工作，理论和实验齐头并进，可以想象，这可能会催生下一次信息革命。该项目在 2D 材料领域拥有领先研究成果的华盛顿大学和大力投资量子计算机应用的当地企业（包括微软）之间架起了一座桥梁。 技术：该项目旨在建立 2D 材料的可行性用于创建可用于拓扑量子处理的马约拉纳零模式的材料平台。该团队采用单层 WTe2 作为二维拓扑绝缘体，并结合二维超导体（NbSe2 或 FeSe）和二维磁体（CrI3 或 CrBr3）。这些材料与电接触和隧道势垒一起堆叠成范德华异质结构。在三种材料相遇的点处，马约拉纳模式可能在低温下出现，并且可以通过隧道测量来探测。与其他马约拉纳系统相比，该 2D 平台具有优势，包括不需要磁场来产生螺旋模式，并且可以避免化学势的精细调整。所涉及的多电子和拓扑物理的复杂性以及系统的新颖性要求实验和理论之间的密切合作。具体目标是诱导和理解 WTe2 螺旋边缘中的超导邻近间隙，并设计和测试最简单的二维可能异质结构器件，其中马约拉纳可能发生并被检测到。该奖项反映了 NSF 的法定使命，并被认为是值得的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来提供支持。

项目成果

Determination of the Spin Axis in Quantum Spin Hall Insulator Candidate Monolayer WTe2

• DOI: 10.1103/physrevx.11.041034
• 发表时间: 2020-10
• 期刊: Physical Review X
• 影响因子: 12.5
• 作者: Wenxuan Zhao;E. Runburg;Z. Fei;J. Mutch;P. Malinowski;Bosong Sun;Xiong Huang;D. Pesin

Magnetic proximity and nonreciprocal current switching in a monolayer WTe2 helical edge

• DOI: 10.1038/s41563-020-0620-0
• 发表时间: 2020-01
• 期刊: Nature Materials
• 影响因子: 41.2
• 作者: Wenjin Zhao;Z. Fei;Tiancheng Song;Han Kyou Choi;T. Palomaki;Bosong Sun;P. Malinowski;M. McGuire;J. Chu;Xiaodong Xu;D. Cobden

Evidence for equilibrium exciton condensation in monolayer WTe2

• DOI: 10.1038/s41567-021-01427-5
• 发表时间: 2021-12-23
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Sun, Bosong;Zhao, Wenjin;Cobden, David H.
• 通讯作者: Cobden, David H.