“Quantum Electronic Transport in Graphene Hybrid Nanostructures”

Dr. GilHo Lee
Department of Physics, POSTECH

Sep. 22 (Fri.), 02:30 PM
E6-2. 1st fl. #1323

Abstract:
Ever since discovered, graphene has brought in high-energy relativistic quantum mechanics to low-energy condensed matter system. Exploiting its unique relativistic characters and electrostatic tunability, ballistic graphene has a great potential leading us to novel electronic optical quantum devices. When electrons tunnel p-n barriers, that is termed by Klein tunneling, they exhibit negative refraction in order to conserve their pseudo-spins. Based on this unique phenomenon, 1) Veselago’s lens was demonstrated in the graphene heterostructure of two sharp p-n barriers. 2) We also demonstrated a quantum switch based on Dirac-fermion optics, where strong angle dependence of Klein tunneling probability enabled collimators and mirrors for electrons. Through systematic measurements, we isolated the net optical contribution and extract a full set of transmission coefficient, demonstrating clear evidences of Dirac fermions’ optical characteristics. Lastly, 3) we firstly induced superconducting correlations in the quantum Hall states in the superconducting heterostructure of high quality graphene. Such heterostructures were suggested to realize emergent excitations of non-Abelian anyons, although its experimental understanding has been lacking so far due to the incompatibility between superconducting and quantum Hall phases. We will discuss this system in terms of a unique platform for realizing universal and scalable topological quantum computers.