1 School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009, China
2 State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
3 Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025, USA
4 State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
5 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
6 Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, UK
7 e-mail: meifeng@sxu.edu.cn
8 e-mail: nyxu@hfut.edu.cn
9 e-mail: hengshen@nbi.dk