Xiaotong Lu,1,2 Chihua Zhou,1,2 Ting Li,1,2 Yebing Wang,1 and Hong Chang 1,2,a) 1 National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, People’s Republic of China 2 University of Chinese Academy of Science, Beijing 100049, People’s Republic of China a)Author to whom correspondence should be addressed: changhong@ntsc.ac.cn ABSTRACT: We present a synchronous frequency comparison method based on one cold-atom ensemble by using the dual-excitation spectrum technique, which can simultaneously detect the probabilities of two different clock transitions. We experimentally verify this synchronous frequency comparison method between |mF|=9/2|mF|=9/2 and |mF|=7/2|mF|=7/2 in a one-dimensional 87Sr optical lattice clock and the comparison instability is well below the Dick limit. We also extend the dual-excitation spectrum method to shorten the clock feedback cycle by a half in optical lattice clocks and experimentally demonstrate that the interleaved self-comparison instability is 1.4 times lower than that of the traditional operation method. This research was supported by the National Natural Science Foundation of China (No. 61775220), the Key Research Project of Frontier Science of the Chinese Academy of Sciences (Grant No. QYZDB-SSW-JSC004), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB21030100). |
