Field-grade atomic clocks capable of primary standard performance in compact physics packages would be of significant value in a variety of applications ranging from network synchronization and secure communications to GPS hold-over and inertial navigation. A cold-atom coherent population trapping (CACPT) clock featuring laser-cooled atoms and pulsed Ramsey interrogation is a strong candidate for this technology if the principal frequency shifts can be controlled and the performance degradation associated with miniaturization can be overcome. In this thesis, research focused on the development of this type of compact atomic clock is presented. To address the low atom numbers obtained in small cold-atom sources, experiments were performed in which an atomic beam was decelerated with bichromatic stimulated laser forces and loaded into a mm-scale magneto-optical trap, increasing the atom number by a factor of 12.5. A CACPT clock using the high-contrast lin||lin optical interrogation technique was developed and achieved a stability of 7 x 10-13 after one hour of integration. Doppler shifts in the clock are explained using a simple kinematic model and canceled by interrogating the atoms with a counter-propagating CPT configuration. Finally, a thorough characterization of the AC-stark effect in lin||lin CPT was performed. Observed shifts are explained in terms of contributions from coherent CPT-generating couplings and population transfer effects caused by optical pumping from incoherent light. Measurements are compared with existing and new theoretical treatments, and a laser configuration is identified that reduces clock drift from light shifts to less than 10-14 for the current system.
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机译：能够在紧凑的物理封装中达到主要标准性能的现场级原子钟在从网络同步和安全通信到GPS保持和惯性导航等各种应用中都将具有重要价值。如果可以控制主要的频移并且可以克服与小型化有关的性能下降，那么采用激光冷却原子和脉冲拉姆西审讯的冷原子相干人口捕获（CACPT）时钟是该技术的强力候选人。本文以这种紧凑型原子钟的发展为研究重点。为了解决在小型冷原子源中获得的低原子序数的问题，进行了实验，其中原子束被双色激发的激光力减速并加载到毫米级的磁光阱中，使原子序数增加了12.5倍。开发了使用高对比度线性光学询问技术的CACPT时钟，并在集成一小时后达到了7 x 10-13的稳定性。使用简单的运动学模型解释了时钟中的多普勒频移，并通过对向传播的CPT配置询问原子来消除多普勒频移。最后，对线性CPT中的AC-斯塔克效应进行了彻底的表征。观察到的偏移是根据相干的CPT产生的耦合的贡献和由非相干光的光泵浦引起的种群转移效应来解释的。将测量结果与现有和新的理论处理进行了比较，并确定了激光配置，该配置可将时钟偏移从光偏移减少到当前系统的10-14以下。
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