Non-fidelity 1 − F of the full transfer driven by Gaussian pulses (Δt = 28 μs) plus weak coupling decay versus the laser half line-width at half-maximum ΓL
Figure 7. Non-fidelity 1 − F of the full transfer driven by Gaussian pulses (Δt = 28 μs) plus weak coupling decay versus the laser half line-width at half-maximum ΓL. Laser parameters are \Omega _B^0/2\pi =400 MHz and \Omega _R^0/2\pi =40 MHz and ΔB/2π = 100 MHz, ΩC/2π = 10 MHz, ΔC/2π = 100 MHz and ΔR = ΔB − ΔC − αCΩC/2.
A stimulated Raman adiabatic passage (STIRAP)-like scheme is proposed to exploit a three-photon resonance taking place in alkaline-earth-metal ions. This scheme is designed for state transfer between the two fine structure components of the metastable D-state which are two excited states that can serve as optical or THz qubit. The advantage of a coherent three-photon process compared to a two-photon STIRAP lies in the possibility of exact cancellation of the first-order Doppler shift which opens the way for an application to a sample composed of many ions. The transfer efficiency and its dependence with experimental parameters are analysed by numerical simulations. This efficiency is shown to reach a fidelity as high as (1–8 × 10−5) with realistic parameters. The scheme is also extended to the synthesis of a linear combination of three stable or metastable states.