Miniature optically pumped cesium beam atomic clock with two-laser pumping

Cesium beam atomic clocks are widely used in various fields due to their excellent long-term stability. Compared to magnetic state selection clocks, optically pumped cesium beam clocks can concentrate more atoms in the clock transition state. However, traditional optical pumping with one laser still results in significant atomic loss, which limits the further improvement of optically pumped cesium beam clocks. Here, we implement and experimentally evaluate optical pumping with two lasers for state preparation to improve the population difference. We conduct a theoretical calculation of the population difference for the two-laser optical pumping scheme and develop a complete system for an optically pumped cesium beam clock. After experimental measurements, the estimated population difference of the two-laser pumping scheme reaches about five times that of the one-laser pumping scheme, thus improving the signal-to-noise ratio of the Ramsey fringes. The short-term frequency stability of the two-laser pumping scheme is 1.5×10−12/τ, which is improved by a factor of 1.47 compared with that of the one-laser pumping scheme with the same cesium beam and electric system.