Atomic clock on the basis of the CPT effect in counter-propagating circularly polarised waves

Abstract

This study explores a Rb CPT atomic clock using two counter-propagating waves with orthogonal circular polarisation. By suppressing the optical pumping effect, the clock demonstrates substantial (several times) improvement in CPT contrast compared to the conventional single circularly polarised wave configuration. The use of two counter-propagating beams also allows for positive interference between two photon transitions excited by anti-parallel waves. A double-pass optical layout improves short-term stability by 1.5 times, achieving a result of 4.5×10–11 over 1 second using a 5-mm long optical cell.