Recent advances in physics incorporating topology have revealed new effects and at the same time made possible many device possibilities. Topological transitions have also been used to demonstrate dissipation-less quantum anomalous Hall in magnetic doped topological insulator and to control spin texture. Topological material heterostructures composed of, e.g., TI and antiferromagnets (AFM) or superconductors are shown to offer interesting new physics. In this talk, the topological transitions at the interfaces of the TI/AFM heterostructure can be controlled by applying a small magnetic field. The edge state of the quantum anomalous Hall using a magnetic doped topological insulator has been demonstrated to have millimeter coherent transport lengths. For the heterostructure consisting of a QAH edge state interfaced with a superconductor, new phase topological phase transitions can also occur and a topological superconductor phase is predicted. For such heterostructure, chiral Majorana can be hosted. Majorana has been under intensive pursuit both theoretically and in experiments in the past. In the heterostructure consisting of a QAH insulator and a superconductor, our recent experimental results showed a half-integer and a two-integer of quantized conduction plateaus (0.5 e2 /h and 2 e2 /h), which give the firm signatures of the elusive Majorana fermion for the first time in 80 years. A recent report of different systems using an InSb nanowire interfaced with a superconductor confirmed a similar two-quantized plateau. The contrast of our results with the more recent confirmation using the InSb nanowire with a superconductor mentioned above will also be discussed . More recently, a half quantization of thermal conductance was also confirmed in RuCl3. Using Majorana particles as topological qubits, topological quantum computer may be realized. The findings offer a new direction for robust topological quantum computing to mitigate the de-coherence challenge. Our finding offers a potential for constructing a robust topological approach to mitigate the challenge of decoherence of today’s approaches in quantum computer.
Dr. Kang L. Wang is currently Distinguished Professor and the Raytheon Chair Professor in Physical Science and Electronics in the University of California, Los Angeles (UCLA). He is affiliated with the Departments of ECE, MSE and Physics/Astronomy. He received his MS and PhD degrees from the Massachusetts Institute of Technology and his BS degree from National Cheng Kung University (Taiwan). He is a Guggenheim Fellow, Fellows of American Physical Society and IEEE, a Laureate of Industrial Technology Research Institute of Taiwan and an Academician of Academia Sinica. His awards include the IUPAP Magnetism Award and Néel Medal, the IEEE J.J. Ebers award for electron devices, SRC Technical Excellence Award, the Pan Wen-Yuan Award, Chinese American History Makers Award, and others. He served as the editor-in-chief of IEEE TNANO, editors of Artech House, J of Spins, Science Advances and other publications. His research areas include topological insulators – materials and physics; spintronics and nonvolatile electronics, and nanoscale physics and quantum matters; molecular beam epitaxy.