1. Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
2. School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
3. Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543