1. Department of Engineering Physics, Tsinghua University, Beijing 100084, China
2. State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
3. Microsystem and Terahertz Research Center, China Academy of Engineering Physics, Chengdu 610200, China
4. Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
5. Advanced Micro-Fabrication Equipment Inc., Shanghai 201201, China
6. Collaborative Innovation Center of Quantum Matter, Beijing 100871, China