Compact optically pumped cesium beam atomic clock with a 5-day frequency stability of 7×10^-15

Compared to other commercial atomic clocks in the time keeping field, the greatest advantage of cesium beam atomic clocks is their superior long-term stability. Compared to magnetic state-selection clocks, optically pumped cesium beam atomic clocks have more interacting atoms, which results in better stability potential. To achieve good long-term stability, we propose methods including stabilization of laser power and reconstruction of circuits. They play a key role in the long-term stability of cesium beam atomic clocks. After 75 days of continuous running and measurement, we released the 5-day stability results (7×10^-15 Allan deviation) of our optically pumped cesium beam atomic clock. To the best of our knowledge, this is the best 5-day stability result ever reported for compact optically pumped cesium beam atomic clocks.