Improved high resolution spectroscopy with cold magnesium atoms

We report on recent results in high precision spectroscopy with cold magnesium atoms. Resolutions as high as 290 Hz have been achieved with our Ramsey-Borde interferometer tuned to the 3¹S₀→3³P₁ intercombination line at 457.2 nm. The potential short-term stability inferred from the interference signal is 8×10^-14 in 1 s. The residual atomic motion of the atoms, cooled to the Doppler limit, is identified as a main contribution to the contrast decay. In order to improve the performance of our interferometer, we are currently setting up a second experiment, where we can push the temperature limit to the μK-regime.