1. State Key Laboratory of Information Photonics and Optical CommunicationsSchool of ScienceBeijing University of Posts and Telecommunications P.O. Box 91 Beijing 100876 China
2. Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
3. State Key Laboratory of Superlattices and MicrostructuresInstitute of SemiconductorsChinese Academy of Sciences & Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100083 China
4. Beijing Academy of Quantum Information Sciences Beijing 100193 China