Prof Andrew Steane

Abstract:

We report a measurement of the lifetime of the 3d 2D5/2 metastable level in 40Ca+, using quantum jumps of a single cold calcium ion in a linear Paul trap. The 4s 2S1/2-3d 2D5/2 transition is significant for single-ion optical frequency standards, astrophysical references, and tests of atomic structure calculations. We obtain τ = 1.168±0.007 s from observation of nearly 64 000 quantum jumps during ∼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 2D3/2. We also use quantum jump observations to demonstrate photon antibunching, and to estimate background pressure and heating rates in the ion trap. ©2000 The American Physical Society.

Abstract:

The speed limit at which general processing operations can be driven in the ion-trap system was theoretically and experimentally studied. Focus was on the intrinsic limitations imposed by the physics of the system, such as the tightness of the trap and the presence of a rich energy-level structura in the vibrational modes. The obtained data were analyzed in detail.

Abstract:

A linear ion trap apparatus was used to measure the lifetime of the D5/2 level in 40Ca+ by quantum jump measurements on a single trapped ion. Compared to previous measurements, more precise and significantly larger results were obtained. Overall, the apparatus provided a precise test of ab initio atomic structure calculations.

Abstract:

We report a precise search for correlation effects in linear chains of 2 and 3 trapped Ca+ ions. Unexplained correlations in photon emission times within a linear chain of trapped ions have been reported, which, if genuine, cast doubt on the potential of an ion trap to realize quantum information processing. We observe quantum jumps from the met astable 3d2 D5/2 level for several hours, searching for correlations between the decay times of the different ions. We find no evidence for correlations: the number of quantum jumps with separations of less than 10 ms is consistent with statistics to within errors of 0.05%; the lifetime of the metastable level derived from the data is consistent with that derived from independent single-ion data at the level of the experimental errors (1%); and no rank correlations between the decay times were found with sensitivity to rank correlation coefficients at the level of |R| = 0.024.