Frequency drift detection method using dual alkali gas for coherent population trapping atomic clocks

We propose a frequency drift detection method for coherent population trapping (CPT) atomic clocks to improve their long-term frequency stability. One of the main reasons for frequency drift in gas-cell based atomic clocks is buffer gas pressure variations in the gas cells caused by leakage through the cell walls. In this work, the drift detection method is demonstrated experimentally using a dual alkali microelectromechanical system (MEMS) cell.