1 State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
2 Frontier Science Center for Quantum Information, Beijing 100084, China
3 School of Information Science and Technology, Tsinghua University, Beijing 100084, China
4 Beijing National Research Center for Information Science and Technology, Beijing 100084, China
5 Beijing Academy of Quantum Information Sciences, Beijing 100193, China
6 e-mail: yinlg@tsinghua.edu.cn
7 e-mail: gllong@tsinghua.edu.cn