ATOMIC CLOCK SYSTEM

An atomic clock system includes a waveguide cavity that is sealed and comprises a gas enclosed therein. The waveguide cavity has a length that is an integer multiple of approximately one half-wavelength of a resonant frequency of the gas between two states. An oscillator system generates an RF signal through the waveguide cavity. The RF signal has a signal frequency that is approximately equal to the resonant frequency of the gas. A detection system measures a characteristic of the RF signal through the waveguide cavity to detect a maximum transition between the two states of the gas and to provide a feedback signal to the oscillator system to lock the signal frequency of the RF signal to the resonant frequency of the gas based on detecting the maximum transition. The detection system provides a frequency reference output signal based on the signal frequency of the RF signal.