通过减小碰撞导致的退相干和谱线增宽提高光晶格钟稳定度  

Stability Improvement of Optical Lattice Clocks by Reducing Collision-Induced Decoherence and Broadening Spectrum Line

作　　者：周驰华 卢晓同 郭峰 王叶兵[1,2] 梁婷 常宏 Zhou Chihua;Lu Xiaotong;Guo Feng;Wang Yebing;Liang Ting;Chang Hong(Key Laboratory of Time and Frequency Primary Standards of Chinese Academy of Sciences,National Time Service Center,Chinese Academy of Sciences,Xi'an 710600,Shaanxi,China;School of Astronomy and Space Science,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院国家授时中心时间频率基准重点实验室,陕西西安710600 [2]中国科学院大学天文与空间科学学院,北京100049

出　　处：《光学学报》2023年第9期1-8,共8页Acta Optica Sinica

基　　金：国家自然科学基金(11803042,11474282,61775220);中国科学院前沿科学重点研究项目(QYZBD-SSW-JSC004);中国科学院青年创新促进会专项(2019400);陕西省青年科技新星项目(2021KJXX-58)。

摘　　要：在87Sr空间光晶格钟原理样机上实验观测了原子碰撞对谱线激发率抑制以及对谱线的展宽,并观测到由非弹性碰撞导致的原子损耗。通过简单地将原子数从6000减小至2000,实现了线宽为1.9 Hz的钟跃迁谱线,并将空间光晶格钟原理样机的稳定度提升至1×10^(-15)(τ/s)^(-0.5)。相关实验结果对研究光晶格的多体相互作用对钟跃迁谱线的影响具有重要意义。Objective System stability and uncertainty are the two most important indicators of a clock,which represent the fluctuation of the clock output frequency in the time domain and the possible deviation between the clock output frequency and the absolute frequency,respectively.Stability improvement can reduce the measurement error of system frequency shifts and thus decrease systematic uncertainty.At present,the factors that limit the stability of an optical lattice clock mainly include quantum projection noise and Dick noise.By extending the optical probing time(τ_(p)),the effective operating rate of the clock can be improved,and the quantum projection noise and Dick noise can be reduced at the same time.However,compared with those of a case having smallerτ_(p)(such as 100 ms),the collisional frequency shifts are in the same order of magnitude as the Rabi frequency,and the loss of particles in the excited state due to inelastic scattering is enhanced when bothτ_(p) and the number of atoms are large(e.g.,τ_(p)=500 ms,N=6000).At the same time,the difference in Rabi frequency between the atoms in different external states and different lattice sites also rises(inhomogeneous excitation induced by atomic temperature,atomic interactions,clock laser frequency noise,and the detuning angle between the clock laser and the lattice light).All these factors make the excitation fraction of the clock transition spectrum line decrease and the linewidth widen whenτ_(p) is large and eventually lead to the stability of the clock below the corresponding Dick limit.Methods In this paper,based on the prototype of the ^(87)Sr one-dimensional space optical lattice clock,we experimentally observe the influence of atomic interactions on spectral linewidth and excitation fraction and even the corresponding influence on system stability.In the experiment,we measure the Rabi spectrum of clock transition at 6000 and 2000 atoms.In the measurements,the atomic temperature is kept at 3μK(for T is constant,the number of atoms is proportional t

关 键 词：原子与分子物理学 空间光晶格钟 钟跃迁谱线 相互作用 自比对稳定度 

分 类 号：O562.5[理学—原子与分子物理]