1. School of Science, Harbin Institute of Technology, Shenzhen 518055, China
2. Key Laboratory of Micro-Nano Optoelectronic Information System of Ministry of Industry and Information Technology, Harbin Institute of Technology, Shenzhen 518055, China
3. School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, U.K.
4. Department of Physics, Paderborn University, Warburger Straße 100, D-33098 Paderborn, Germany
5. Department of Materials Science and Engineering, Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China