A Magnesium Optical Clock

Summary form only given. We investigated a novel method which is based on a coherent two photon-process which provides higher velocity selectivity. The method extends standard Doppler cooling based on the transition 3¹S₀ rarr 3¹P₁ by coupling the excited state with an additional laser to the ¹D₂ level. This gives the possibility to modify the population in the intermediate state 3¹P₁ and thus the mechanical light force, which in our experiments is actually dominated by the photons of the strong cooling transition.