A Systems Analysis of the Cesium Beam Atomic Clock

A brief derivation of the transition probability for a two-state atomic system subjected to a phase modulated oscillatory perturbation is presented. This result is used to perform an analysis of a typical cesium beam atomic clock system utilizing a Ramsey (twin cavity) beam tube in order to determine optimum design parameters. It is shown theoretically and experimentally that the optimum modulation frequency for this type of system is higher than has previously been supposed. An additional feedback loop can be incorporated to nearly eliminate cavity phase error.