1. State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China
2. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China
3. Department of Physics Beijing Technology and Business University Beijing 100048 China
4. Center for Excellence in Topological Quantum Computation University of Chinese Academy of Science Beijing 100049 China