作者机构:[1]College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China, [2]Institute of Modern Physics, the Chinese Academy of sciences, Lanzhou 730000, China
相关基金:supported by National Natural Science Foundation of China (Nos. 10774122, 10876028), the specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20070736001) and the Foundation of Northwest Normal University of China (NWNU-KJCXGC-03-21)