1. College of Physics, Center for Marine Observation and Communications, Qingdao University, Qingdao 266071, China
2. Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
3. Institute for Quantum Computing, Department of Electrical and Computer Engineering, University of Waterloo, Waterloo N2L 3G1, Canada
4. School of Physics, Shandong University, Jinan 250100, China
5. Department of Physics, School of Science, Harbin Institute of Technology, Harbin 150001, China