1. Synergetic Innovation Center for Quantum Effects and Application, Key Laboratory of Low‐dimensional Quantum Structures and Quantum Control of Ministry of Education, Key Laboratory for Matter Microstructure and Function of Hunan Province, School of Physics and Electronics Hunan Normal University Changsha 410081 P. R. China
2. Department of Applied Physics The Hong Kong Polytechnic University Hong Kong 999077 P. R. China