Atomic clocks based on coherent population trapping

Coherent population trapping is a phenomenon in which atoms are prepared and detected in superpositions of their ground state energy levels through illumination by bichromatic optical fields. We describe the use of coherent population trapping in the development of compact atomic clocks based on both room temperature vapors and laser cooled ensembles. The use of coherent population trapping allows for a high degree of miniaturization as well as some performance advantages such as a reduction in the first-order Doppler shift.