双电子的原子相干及其在光频标中的应用

项目名称： 双电子的原子相干及其在光频标中的应用

项目编号： No.11474282

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 常宏

作者单位： 中国科学院国家授时中心

项目金额： 91万元

中文摘要： 碱土金属最外层为双价电子的原子系统中，原子能级具有单态和三重态。理论研究表明利用单态和三重态间的偶极禁戒跃迁可以实现双电子的原子相干。对于这种由电子-电子相互作用导致的原子相干谱，谱线线宽可突破探测激光线宽对跃迁谱直接测量的限制，可达禁戒跃迁自然线宽量级（mHz）。这将在光频标和高分辨率光谱等领域有重要的应用潜力。 本项目计划开展双电子系统中的原子相干效应的实验研究，利用超稳、超窄线宽激光光源实现相位严格相关的耦合光场和探测光场。 通过外光场耦合锶原子5s5s1S0-5s5p3P0偶极禁戒跃迁，在考虑由LS耦合导致自旋对称性破缺和核自旋的情况下的能级简并，在加入ss耦合作用下，可以构成双电子Λ型原子相干。实验研究这种双电子系统原子相干谱，测量多光子共振处外探测光场的频率，实现对锶原子钟频率的精确测量。利用这种钟频测量实现的锶原子光频标有望实现10-18量级。

中文关键词： 原子分子物理；激光光谱；原子频标

英文摘要： The atoms with two valance electrons, e.g. alkaline earth metals, the energy structures of these elements consistent of single state and triplet states. From the analysis forbidden transition of 1S0-3P0 of these two electrons systems, driven by the laser fields need for atomic coherence a conceptually new kind of atomic coherence appear. The linewidth of this kind spectrum can be less than the linewidth of probe laser. The resolution of this spectrum can be mHz, that is the natural lindwidth of dipole forbidden transition. This will have great potential applications in the optical frequency standard and high resolution spectroscopy etc.. Our project is planned to carry out the experimental of atomic coherence effect in two-electron systems. The coupling light and the probe light generated by one ultra-narrow linewidth laser and the phase of these two light fields strictly related. With the external light coupling strontium atom 5s5s1S0-5s5p3P0 transitions, in considering the spin symmetry breaking and nuclear spin, a two electrons atomic coherence can be constructed. We will study the character of the two electron atomic coherence spectrum experimentally. The frequency of 5s5s1S0-5s5p3P0 transition can be accuratly measured the frequency of probe-laser in resonance of multi-photons, and then we can achieve frequency measurement of strontium atomic clock. With this method, the frequency instability of strontium atom optical clock can achieve to 10-18.

英文关键词： Atomic and molecular physics;Laser spectroscopy;Atomic frequency standard