Physics Package Based on Intracavity Laser Cooling 87Rb Atoms for Space Cold Atom Microwave Clock

This article proposes a new physics package to enhance the frequency stability of the space cold atom clock with the advantages of a microgravity environment. Clock working processes, including atom cooling, atomic state preparation, microwave interrogation, and transition probability detection, are integrated into the cylindrical microwave cavity to achieve a high-performance and compact physics package for the space cold atom clock. We present the detailed design and ground-test results of the cold atom clock physics package in this article, which demonstrates a frequency stability of 1.2 × 10-12 τ-1/2 with a Ramsey linewidth of 12.5 Hz, and a better performance is predicted with a 1 Hz or a narrower Ramsey linewidth in microgravity environment. The miniaturized cold atom clock based on intracavity cooling has great potential for achieving space high-precision time-frequency reference in the future.

本文提出一种新型物理封装组件（physics package），借助微重力环境的优势以提升空间冷原子钟的频率稳定度。本文将原子冷却、原子态制备、微波问询（microwave interrogation）及跃迁概率探测等冷原子钟工作流程集成至圆柱形微波谐振腔（cylindrical microwave cavity）内，从而为空间冷原子钟打造高性能、紧凑型的物理封装组件。本文详述了该冷原子钟物理封装组件的详细设计方案与地面试验结果：其当前频率稳定度可达1.2×10^-12 τ^-1/2，拉姆齐线宽（Ramsey linewidth）为12.5 Hz；在微重力环境下，若拉姆齐线宽达到1 Hz或更窄，则可实现更优异的性能表现。基于腔内冷却的紧凑型冷原子钟，未来在构建空间高精度时频基准方面具备巨大应用潜力。