1. Institute of Physics and Electronic Engineering, Sichuan University of Science and Engineering, Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education, Zigong 643000, China
2. Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of Education, College of Physics and Information Science, Hunan Normal University, Changsha 410081, China
3. Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824, USA