Funding for this research was provided by:
Julian Schwinger Foundation for Physics Research (15-07-0000)
National Natural Science Foundation of China (11705162)
Natural Science Foundation of Jiangsu Province (BK20170479)
Postdoctoral Research Foundation of China (17Z102060070)
Article History
Received: 1 March 2019
Accepted: 11 July 2019
First Online: 16 July 2019