1. Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
2. Department of Physics, Hong Kong University of Science and Technology, Hong Kong 999077, China.
3. State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
4. Frontier Science Center for Quantum Information, Beijing 100084, China.
5. Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
6. Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA.
7. Min H. Kao Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN 37996, USA.