Eur. Phys. J. D 7, 461-465 (1999)
https://doi.org/10.1007/s100530050590

3d ²D_5/2 lifetime in laser cooled Ca⁺: Influence of cooling laser power

Institut für Physik, Universität Mainz, 55099 Mainz, Germany

Received: 3 March 1999
Published online: 15 October 1999

Abstract

We have measured the lifetime of the metastable 3D_5/2 level in Ca⁺ using the "quantum jump" technique on a single stored and laser cooled ion in a linear Paul trap. We found a linear dependence of the measured decay rate on the power of the laser which repumps the ions from the long lived 3D_3/2 level. This can be explained by off-resonant depletion of the 3D_5/2 level. The proper lifetime of this level is obtained by a linear extrapolation of the measured lifetime to zero laser power. We obtain 1100(18) ms in agreement with theoretical calculations. The observed systematic change of the decay rate resolves discrepancies between earlier experiments in which this effect had not been considered. Measurements on a linear chain of 10 laser cooled ions showed unexpected frequent coincidences of quantum jumps within our observation time of 20 ms. This indicates a so far unexplained correlation between the ions in the chain at large distances.