Measurement of the lifetime of the 3d D-2(5/2) state in Ca-40(+) - art. no. 032503

We report a measurement of the lifetime of the 3d(2)D(5/2) metastable level in Ca-40(+), using quantum jumps of a single cold calcium ion in a linear Paul trap. The 4s S-2(1/2)-3d D-2(5/2) transition is significant for single -ion optical frequency standards, astrophysical references, and tests of at omic structure calculations. We obtain tau = 1.168 +/- 0.007 s from observa tion of nearly 64 000 quantum jumps during similar to 32 h. Our result is m ore precise and significantly larger than previous measurements. Experiment s carried out to quantify systematic effects included a study of a previous ly unremarked source of systematic error, namely, excitation by the broad b ackground of radiation emitted by a semiconductor diode laser. Combining ou r result with atomic structure calculations yields 1.20 +/- 0.01 s for the lifetime of 3d D-2(3/2). We also use quantum jump observations to demonstra te photon antibunching, and to estimate background pressure and heating rat es in the ion trap.