Journal of Physics B Atomic Molecular and Optical Physics
Quantum jumps in singly ionized magnesium
Hebe Powell, Martijn A. van Eijkelenborg, William M. Irvine, D. M. Segal, Richard Claude Thompson
Abstract
The quantum jump statistics for the three stable isotopes of Mg + have been studied experimentally. Single ions of magnesium were held and laser cooled in a Penning trap. Quantum jumps were observed by collecting the resonance fluorescence near 280 nm from the cooled ion. The jump rate was analysed to find ratios of the average time the ion spends fluorescing, `on' time, to the average time it spends in the dark state, `off' time: for both 24 Mg + and 26 Mg + this value was found to be 15.9±1.2, in agreement with a theoretical value of 16.0. The presence of hyperfine structure in 25 Mg + means that while the jump rate for 24 Mg + and 26 Mg + remains unaltered for both available cooling transitions, for the odd isotope the on to off ratio is predicted to be 11.8 and 22.8 for the lower and upper transitions respectively. Experimental values for these ratios were found to be 10.2 ± 0.7 and 22.0 ± 0.6. The occurrence of so-called nuclear jumps in 25 Mg + is investigated qualitatively. These rare jumps are produced as a result of the hyperfine splitting, which is only present in the odd isotope. Although the data indicate some evidence for this type of jump, it is not possible to draw any firm conclusions due to the small number of events observed.