作者机构:[1]School of Physical Science and Technology, Southwest University, Chongqing 400715, China, [2]Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
相关基金:Supported by National Nature Science Foundation of China (No.10205019, 10475098), Doctoral Foundation of Southwest University (No. SWNUB2005028) and Hundred Talent Project of CAS (0501080BR0)