1. State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
2. Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
3. RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
4. Institute for Advanced Study, Tsinghua University, Beijing 100084, China