作者机构:[1]School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China, [2]Department of Physics, Tsinghua University, Beijing 100084, China
相关基金:Supported by the National Fundamental Research Program under Grant No. 2010CB923202, Specialized Research Fund for the Doctoral Program of Education Ministry of China under Grant No. 20090005120008, the Fundamental Research Funds for the Central Universities under Grunt No. BUPT2009RC0710, China National Natural Science Foundation under Grant Nos. 60871082, 60937003 and 10947151