Probing non-Abelian Quasiparticles with Johnson Noise Limited Measurements

非技术描述：直到不久以前，人们还认为，在凝聚态物质系统中观察到的大量相有一个统一的相理论。然而，在20世纪80年代后期，所谓的拓扑有序相显然超出了这种传统的理解。由于新的基础物理学及其在新型量子存储器和量子计算中的应用，非阿贝尔拓扑相引起了人们的广泛关注。然而，尽管有广泛的理论工作和持续的测量努力，对这种非阿贝尔粒子的观测仍然是难以捉摸的。这个项目的目标是寻找非阿贝尔粒子的实验特征，非阿贝尔相的新粒子，使用灵敏度最高的电子检测。本项目为培养研究生和本科生在现代电子物理、半导体纳米制造、低温学和量子计算入门等方面的技能提供了极好的机会，这些技能对科学技术的成功载体有用。PI已经参与并将继续与来自代表性不足群体的学生合作。此外，整个印第安纳州的初高中学生将通过发展示范和基于探究的活动，希望激励他们走上科学和工程的职业生涯。技术描述：拓扑有序量子相的研究已成为凝聚态物理学中最令人兴奋的课题之一。一种特殊类型的拓扑量子相可能包含非阿贝尔准粒子，这是一种全新的粒子。非阿贝尔准粒子与众所周知的玻色子和费米子有很大的不同，因为它们具有电子的一小部分电荷，并且被预测服从非阿贝尔统计。尽管有完善的理论和持续的实验努力，但在明确探测这些非阿贝尔准粒子方面进展甚微。PI提出了实验研究和教育，以解决GaAs/AlGaAs量子阱中二维电子气体中实现的非阿贝尔相性质的突出问题，特别是非阿贝尔分数量子霍尔态。使用我们新开发的基于squid的放大器，我们将执行接近约翰逊噪声极限的精确测量。我们的实验提供了一个难得的机会，证明了一种具有非阿贝尔统计的新粒子的存在，并将有助于更好地理解超导体-半导体混合结构，拓扑超流体和超导体，拓扑绝缘体和奇异原子凝聚体中其他被广泛研究的拓扑相。

Nontechnical description:Until not long ago, it was thought that the large number of phases observed in condensed matter systems has a unifying underlining theory of phases. In the late 1980's it became apparent, however, that the so called topologically ordered phases are beyond this conventional understanding. Because of new fundamental physics and applications to novel types of quantum memories and to quantum computing, the non-Abelian topological phases have generated a lot of excitement. Nonetheless, the observation of such non-Abelian particles remains elusive in spite of extensive theoretical work and sustained efforts in measurements. The goal of this project is to look for experimental signatures of non-Abelian particles, novel particles harbored by non-Abelian phases, using electronic detection of the highest sensitivity. This project offers an excellent opportunity to train graduate and undergraduate students in modern electron physics, semiconductor nanofabrication, cryogenics, and introductory quantum computing, skills which are useful for a successful carrier in science and technology. The PI has involved and will continue to work with students from underrepresented groups. Furthermore, middle and high school students throughout the state of Indiana will be reached through the development of demonstrations and inquiry based activities with the hope of inspiring them to embark on a career in the sciences and engineering.Technical description:The study of the quantum phases with topological order has become one of the most exciting topics in condensed matter physics. One special type of topological quantum phase may harbor non-Abelian quasiparticles, a fundamentally new type of particles. Non-Abelian quasiparticles differ significantly from the well-known bosons and fermions since they have a fraction of the electron's charge and are predicted to obey non-Abelian statistics. In spite of a well-developed theory and sustained efforts in experiment, there is little progress towards an unambiguous detection of such non-Abelian quasiparticles. The PI proposes experimental research and education addressing outstanding questions on the nature of non-Abelian phases realized in the two-dimensional electron gas hosted in GaAs/AlGaAs quantum wells, specifically on the non-Abelian fractional quantum Hall states. Using our newly developed SQUID-based amplifier we will perform incisive measurements close to the Johnson noise limit. Our experiments offer a rare chance of demonstrating the existence of a new breed of particles with non-Abelian statistics and will contribute to a better understanding of other intensely studied topological phases realized in superconductor-semiconductor hybrid structures, topological superfluids and superconductors, topological insulators, and exotic atomic condensates.