1. Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai 200438, China.
2. National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China.
3. School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
4. Department of Physics, University of Science and Technology of China, Hefei 230026, China.
5. Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
6. Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
7. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China.