Efficient coherent internal state transfer in trapped ions using stimulated Raman adiabatic passage

We demonstrate experimentally how the process of stimulated Raman adiabatic passage (STIRAP) can be utilized for efficient coherent internal state transfer in single trapped and laser-cooled 40Ca+ ions. The transfer from the D3/2 to the D5/2 state, is detected by a fluorescence measurement revealing the population not transferred to the D5/2 state. A coherent population transfer efficiency at the level of 95% in a set-up allowing for the internal state detection of individual ions in a string has been obtained.