- Speaker: Prof. Gil-Ho Lee (POSTECH)
- Date: Wednesday, January 31, 2018, at 17:00
- Place: Jungho Seminar
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, Veselago’s lens was demonstrated in the graphene heterostructure of two sharp p-n barriers. We will also discuss 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 extracted a full set of transmission coefficient, demonstrating clear evidences of Dirac fermions’ optical characteristics. Lastly, we will briefly talk about superconducting correlations induced in the quantum Hall states in the superconducting heterostructure of high quality graphene in terms of a unique platform for realizing universal and scalable topological quantum computers.