Probing non-Abelian Quasiparticles with Johnson Noise Limited Measurements

Purdue University, West Lafayette IN

Investigators

Abstract

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.