1. State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, China.
2. Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
3. Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
4. Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
5. The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK.
6. Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, UK.
7. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.