David Lucas

Abstract:

We describe the latest work in our programme to implement a linear ion trap quantum information processor with Ca-40(+). This is an experimental demonstration of read-out for a qubit which is stored in the spin state of the valence electron, in the ground electronic level.

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 1s-2s energy interval in the muonium (μ+e-) atom has been measured by Doppler-free two-photon laser spectroscopy. A value of 2 455 528 941.0(9.8) MHz has been obtained in good agreement with quantum electrodynamics (QED). The muon-electron mass ratio can be extracted and is found to be 296.768 38(17). The measurement may also be interpreted as a determination of the muon-electron charge ratio as - 1 - 1.1(2.1)·10-9. Corresponding measurements in deuterium using the same experimental setup confirmed the validity of the applied analysis procedure.