标题： 在两个圆偏振光束场中的相干布居囚禁原子钟的光频移抑制 显示英文标题

标题： Light Shift Suppression in Coherent-Population-Trapping Atomic Clocks in the Field of Two Circularly Polarized Light Beams

摘要： 基于碱金属原子蒸气（Rb或Cs）中相干态囚禁（CPT）现象的最新微型原子钟（MACs）正在被研究。提高时钟的频率稳定性是一个迫切的问题，这将在许多应用领域带来重大进展。在这里，我们研究了一种由两个具有相反圆偏振手性的双色光束组成的光场配置。这些光束与Cs D$_1$线（$\lambda$$\approx$$895$ nm）中的光学跃迁共振。这种配置已经用于观察对比度高于标准单光束方案的CPT共振。然而，与之前的研究不同，我们使用了两个独立的泵浦和探测光束的方案，其中探测光束的透射率被单独监测。 实验是在填充缓冲气体的$5$$\times$$5$$\times$$5$ 毫米$^3$蒸汽细胞中进行的。 结果显示，共振的线形会获得不对称性，这种不对称性可以通过光束之间的微波（拉曼）相位有效控制。 作为概念验证，我们研究了这种不对称性如何显著减轻交流斯塔克（光）移位对CPT钟长期频率稳定性的影响。 实验验证分别使用了分布布拉格反射器（DBR）激光器和垂直腔面发射激光器（VCSEL）。 后者在开发MACs方面具有特殊的重要性。 实验结果与基于原子能级双$\Lambda$方案的分析理论定性一致。 显示英文摘要

摘要： The state-of-the-art miniature atomic clocks (MACs) are based on the phenomenon of coherent population trapping (CPT) in alkali-metal atomic vapors (Rb or Cs). Increasing frequency stability of the clocks is an urgent issue that will lead to significant progress in many fields of application. Here, we examine a light field configuration composed of two bichromatic light beams with opposite handedness of their circular polarization. The beams are in resonance with optical transitions in the Cs D$_1$ line ($\lambda$$\approx$$895$ nm). This configuration has already been known for observing CPT resonances of an increased contrast compared to a standard single-beam scheme. However, in contrast to previous studies, we use a scheme with two independent pump and probe beams, where the probe beam transmission is separately monitored. The experiments are carried out with a buffer-gas-filled $5$$\times$$5$$\times$$5$ mm$^3$ vapor cell. It is shown that the resonance's line shape acquires asymmetry which can be efficiently controlled by a microwave (Raman) phase between the beams. As a proof of concept, we study the way how this asymmetry can help to significantly mitigate the influence of ac Stark (light) shift on a long-term frequency stability of CPT clocks. The experimental verification is performed both with a distributed-Bragg-reflector (DBR) laser and a vertical-cavity surface-emitting laser (VCSEL). The latter has a particular importance for developing MACs. The results of experiments are in qualitative agreement with analytical theory based on a double $\Lambda$ scheme of atomic energy levels.