Interference effects in superconductor-quantum Hall hybrid structures

摘要：目前的电子设备依赖于带电电子和空穴的流动。然而，其他类型的准粒子，具有完全不同的电子特性，可以人为地创造和控制。这些准粒子，包括所谓的“马约拉纳费米子”，具有保护它们免受环境扰动的拓扑特性。在过去的几年中，凝聚态物质社区在理解和实际实施拓扑激发方面取得了巨大进展，这有望彻底改变电子学并使量子计算更接近现实。本研究探索在两种典型量子态之间的界面上形成的拓扑状态和激发：整数量子霍尔和超导体。该项目非常强调指导和教育；它涉及从高中到研究生院各个教育阶段的学生。学生们接受了与工业和学术事业相关的测量和纳米制造方法的培训。技术摘要：量子霍尔（QH）效应和超导性的相互作用有望产生新的量子态和激发，如马约拉纳费米子和对偶费米子。本研究使用磁输运方法探索在量子霍尔态和超导体之间的一维界面上形成的量子态。具体而言，本项目主要关注以下几个主要方向：1)研究手性Andreev边缘态及其相干性和干涉特性，以及它们与Majorana费米子的关系。2)研究由具有超导接触的“扭曲双层石墨烯”制成的约瑟夫森结，以寻找马约拉纳零模式和对偶子。超导量子霍尔系统中拓扑激发的物理学表现出根本性的兴趣，并可能使拓扑量子计算更接近现实。该项目涉及研究生、本科生和高中学生，他们接受过与工业和学术事业相关的测量和纳米制造方法的培训。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。

Non-technical Abstract:Present day electronic devices rely on the flow of charged electrons and holes. However, other types of quasiparticles, with entirely different electronic properties, can be artificially created and controlled. These quasiparticles, which include the so called “Majorana fermions”, have topological properties that protect them against perturbations from their environment. Over the past few years, the condensed matter community achieved dramatic progress in understanding and practical implementation of topological excitations, which promise to revolutionize electronics and to bring quantum computing closer to reality. This research explores topological states and excitations formed at the interfaces between two quintessential quantum states: the integer quantum Hall and superconductor. The project strongly emphasizes mentoring and education; it involves students across educational stages from high to graduate school. The students are trained in measurement and nanofabrication methods relevant for both industrial and academic careers. Technical Abstract:The interplay of the quantum Hall (QH) effect and superconductivity is expected to result in novel quantum states and excitations, such as Majorana fermions and parafermions. This research uses magneto-transport methods to explore quantum states formed at the 1D interfaces between quantum Hall states and a superconductor. Specifically, the project focuses on the following major directions: 1) investigation of chiral Andreev edge states, their coherence and interference properties, and their relation to Majorana fermions. 2) the study of Josephson junctions made of “twisted bilayer graphene” with superconducting contacts, in a search for Majorana zero modes and parafermions. The physics of topological excitations in superconducting quantum Hall systems presents fundamental interest and may bring topological quantum computation closer to reality. The project involves graduate, undergraduate, and high school students who are trained in measurement and nanofabrication methods relevant for both industrial and academic careers.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.