Towards a compact atomic clock based on coherent population trapping and the grating magneto-optical trap

摘要

The combination of coherent population trapping (CPT) and laser cooled atoms is a promising platform forrealizing the next generation of compact atomic frequency references. Towards this goal, we have developed anapparatus based on the grating magneto-optical trap (GMOT) and the high-contrast lin ⊥ lin CPT scheme inorder to explore the performance that can be achieved. One important trade-off for cold-atom systems arisesfrom the need to simultaneously maximize the number of cold atoms available for interrogation and the repetitionrate of the system. This compromise can be mitigated by recapturing cold atoms from cycle to cycle. Here, wereport a quantitative characterization of the cold atom number in the recapture regime for our system, which willenable us to optimize this trade-off. We also report recent measurements of the short-term frequency stabilitywith a short-term Allan deviation of 3 ×10~(-11)= τ~(1/2) up to an averaging time of τ = 10 s.