1. School of Microelectronics and Control Engineering, Changzhou University, Changzhou, China
2. Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, China
3. Department of Physics, Yale University, New Haven, CT, USA
4. Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich, Switzerland