1. Department of Engineering Physics, Tsinghua University, Beijing 100084, China
2. Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
3. Center for Applied Physics and Technology, HEDPS, and College of Engineering, Peking University, Beijing 100871, China
4. Center for Applied Physics and Technology, HEDPS, School of Physics, and College of Engineering, Peking University, Beijing 100871, China
5. Graduate School, China Academy of Engineering Physics, Beijing 100088, China