Efficient qubit detection using alkaline-earth-metal ions and a double stimulated Raman adiabatic process

We present a scheme for robust and efficient projection measurement of a qubit consisting of the two magnetic sublevels in the electronic ground state of alkaline-earth-metal ions. The scheme is based on two stimulated Raman adiabatic passages involving four partially coherent laser fields. We show how the efficiency depends on experimentally relevant parameters: Rabi frequencies, pulse widths, laser linewidths, one- and two-photon detunings, residual laser power, laser polarization, and ion motion.