1. State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
2. Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100084, China
3. Department of Physics, Beijing Normal University, Beijing 100875, China
4. Frontier Science Center for Quantum Information, Beijing 100084, China
5. Beijing Advanced Innovation Center for Future Chips, Beijing 100084, China