Since the notion of topological insulator (TI) was envisioned about a decade ago, topology has become a new paradigm in condensed matter physics. Realization of topology as a generic property of materials has led to numerous predictions of unprecedented phenomena such as magnetic dipoles, axion electrodynamics, resistance-free conduction etc. However, only a very small subset of these predictions have been materialized in real materials, especially in the quantum regime. Here, I will show that defects have been the major culprit behind this slow progress. Once we suppress these defects using various thin film engineering tricks, a series of topological quantum effects such as quantized Faraday/Kerr rotations, quantum Hall effects, topological quantum phase transitions, zeroth Landau level physics etc. start to emerge above otherwise murky ocean of classical topological effects. We are now entering the age of topological quantum materials, but only as far as we can control the defects.
Seongshik Oh has got his BS and MS from Seoul National University in 1992 and 1994 respectively. After serving in Korean Air Force for three years as a meteorologist, he came to University of Illinois, Urbana-Champaign, in 1997 and got his PhD in 2003 on atomically-engineered complex oxides and high Tc cuprate superconductors. Then he joined the quantum computing team (then led by John Martinis, the current leader of the Google Quantum Computing program) at NIST, Boulder, CO, worked on materials problems of superconducting qubits, and developed the first epitaxial qubit. He then joined Rutgers University in 2007 as an assistant professor, and was promoted to an associated professor in 2013 and to a professor in 2018. He is the recipient of a NSF CAREER award in 2009 and since 2014, has been one of the twelve nation-wide EPiQS materials synthesis investigators selected by Gordon and Betty Moore Foundation. Currently, he is one of the internationally-recognized leaders in thin film topological materials.