1. Department of Instrument Science and Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
2. National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai 200240, China
3. School of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), and National Demonstration Center for Experimental Physics Education, Shanghai Jiao Tong University, Shanghai 200240, China