EAGER BRAIDING: Transport Studies of the Anyon Braiding

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.