About the Authors

Zedong Bi

Affiliation State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China

Hai-Jun Zhou

zhouhj@itp.ac.cn

Affiliation State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: HJZ. Performed the experiments: ZB HJZ. Analyzed the data: ZB HJZ. Contributed reagents/materials/analysis tools: HJZ. Wrote the paper: HJZ.