1. State Key
Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
2. National Center for Nanoscience and Technology, No. 11 Beiyitiao, Zhongguancun, Beijing 100190, China
3. The MOE Key Laboratory of Weak-Light Nonlinear Photonics,
TEDA Applied Physics School and School of Physics, Nankai University, Tianjin 300457, China
4. Department
of Physics, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerpen, Belgium
5. Synergetic Innovation Center of Quantum Information and
Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
6. School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States