1 Center for Brain Inspired Computing Research, Department of Precision Instrument, Tsinghua University, Beijing, P. R. China. liguoqi@mail.tsinghua.edu.cn.
2 Beijing Innovation Center for Future Chip, Tsinghua University, Beijing, P. R. China. liguoqi@mail.tsinghua.edu.cn.
3 Center for Brain Inspired Computing Research, Department of Precision Instrument, Tsinghua University, Beijing, P. R. China.
4 Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA, USA.
5 School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore. egxxiao@ntu.edu.sg.
6 Beijing Innovation Center for Future Chip, Tsinghua University, Beijing, P. R. China.
7 School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
8 Center for Brain Inspired Computing Research, Department of Precision Instrument, Tsinghua University, Beijing, P. R. China. lpshi@mail.tsinghua.edu.cn.
9 Beijing Innovation Center for Future Chip, Tsinghua University, Beijing, P. R. China. lpshi@mail.tsinghua.edu.cn.
10 Center for Polymer Studies, Department of Physics, Boston University, Boston, USA.