1. National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University 1 , Nanjing 210093, China
2. Atom Manufacture Institute (AMI) 2 , Nanjing 211805, China
3. Department of Physics, Nanjing Tech University 3 , Nanjing 211816, China
4. National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University 4 , 210093 Nanjing, China