1. School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
2. Department of Physics, State Key Laboratory of Low-dimensional Quantum Physics, Tsinghua University, Beijing, China
3. School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, China
4. School of Physics, Liaoning University, Shenyang, China
5. School of Physical Sciences, and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, China