Malossi, N.2; Damkjær, S.2; Hansen, P. L.2; Jacobsen, L. B.2; Kindt, L.2; Sauge, S.2; Thomsen, Jan Westenkær3; Cruz, F. C.2; Allegrini, M.2; Arimondo, E.2
1 Quantop, The Niels Bohr Institute, Faculty of Science, Københavns Universitet2 unknown3 Quantop, The Niels Bohr Institute, Faculty of Science, Københavns Universitet
A two-photon mechanism for cooling atoms below the Doppler temperature is analyzed. We consider the magnesium ladder system (3s2)S01¿(3s3p)P11 at 285.2nm followed by the (3s3p)P11¿(3s3d)D21 transition at 880.7nm . For the ladder system quantum coherence effects may become important. Combined with the basic two-level Doppler cooling process this allows for reduction of the atomic sample temperature by more than a factor of 10 over a broad frequency range. First experimental evidence for the two-photon cooling process is presented and compared to model calculations. Agreement between theory and experiment is excellent. In addition, by properly choosing the Rabi frequencies of the two optical transitions a velocity independent atomic dark state is observed.
Physical Review a (atomic, Molecular and Optical Physics), 2005, Vol 72