Measurement of the lifetime of the 3d 2D5/2 state in 40Ca+ -: 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 atomic structure calculations. We obtain tau = 1.168 +/- 0.007 s from observation of nearly 64 000 quantum jumps during similar to 32 h. Our result is more precise and significantly larger than previous measurements. Experiments carried out to quantify systematic effects included a study of a previously unremarked source of systematic error, namely, excitation by the broad background of radiation emitted by a semiconductor diode laser. Combining our 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 demonstrate photon antibunching, and to estimate background pressure and heating rates in the ion trap.