title: Competing ν = 5/2 fractional quantum Hall states in confined geometry.
abstract: Some theories predict that the filling factor 5/2 fractional quantum Hall state can exhibit non-Abelian statistics, which makes it a candidate for fault-tolerant topological quantum computation. Although the non-Abelian Pfaffian state and its particle-hole conjugate, the anti-Pfaffian state, are the most plausible wave functions for the 5/2 state, there are a number of alternatives with either Abelian or non-Abelian statistics. Recent experiments suggest that the tunneling exponents are more consistent with an Abelian state rather than a non-Abelian state. Here, we present edge-current-tunneling experiments in geometrically confined quantum point contacts, which indicate that Abelian and non-Abelian states compete at filling factor 5/2. Our results are consistent with a transition from an Abelian state to a non-Abelian state in a single quantum point contact when the confinement is tuned. Our observation suggests that there is an intrinsic non-Abelian 5/2 ground state but that the appropriate confinement is necessary to maintain it. This observation is important not only for understanding the physics of the 5/2 state but also for the design of future topological quantum computation devices.
authors: International Center for Quantum Materials, Peking University, Beijing 100871, China.
authors: Hailong
authors: H
authors: Fu
authors: International Center for Quantum Materials, Peking University, Beijing 100871, China.
authors: Pengjie
authors: 0000-0002-1427-6599
authors: P
authors: Wang
authors: International Center for Quantum Materials, Peking University, Beijing 100871, China.
authors: Pujia
authors: P
authors: Shan
authors: International Center for Quantum Materials, Peking University, Beijing 100871, China.
authors: Lin
authors: L
authors: Xiong
authors: Department of Electrical Engineering, Princeton University, Princeton, NJ 08544.
authors: Loren N
authors: LN
authors: Pfeiffer
authors: Department of Electrical Engineering, Princeton University, Princeton, NJ 08544.
authors: Ken
authors: K
authors: West
authors: Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139; mkastner@sciphil.org xilin@pku.edu.cn.|Science Philanthropy Alliance, Palo Alto, CA 94306.
authors: Marc A
authors: MA
authors: Kastner
authors: International Center for Quantum Materials, Peking University, Beijing 100871, China; mkastner@sciphil.org xilin@pku.edu.cn.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors: Xi
authors: X
authors: Lin
keywords: 5/2 fractional quantum Hall state; edge-current tunneling; fractional quantum Hall effect; non-Abelian statistics; quantum point contact