1. State Key Laboratory of Low‐Dimensional Quantum Physics Department of Physics Tsinghua University Beijing 100084 China
2. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China
3. Department of Physics Stanford University Stanford CA 94305‐4045 USA
4. State Key Laboratory of Surface Physics Department of Physics Fudan University Shanghai 200433 China
5. Collaborative Innovation Center of Quantum Matter Beijing 100084 China