CPT atomic clock based on rubidium 85

We present a compact physics package based on coherent population trapping (CPT) in rubidium 85. The architecture of the package is described along with results obtained using optical- and microwave spectroscopy. We also report the stability of the CPT resonance to variations in operating parameters such as microwave modulation power and vapour cell temperature. With this package we obtain a short term frequency stability σ_y(τ) = 7·10^-11·τ^-1/2 (τ <; 100 sec) and σ_y(τ) ~ 1·10^-11 ( 100 sec <; τ <; 10⁴ sec).