We describe the results of stimulated Raman spectroscopy between the fine-structure levels, specifically $3d^2{D}_{3/2}$ and $3d^2{D}_{5/2}$ metastable states, in a single trapped ${{}^{40}\text{C}\text{a}}^{+}$. Transitions between different Zeeman sublevels, split by an applied magnetic field, are clearly observed and the fine-structure level separation of $\nu =1819599021504\pm 37\text{Hz}$ is determined. This measurement provides a direct observation of this level separation. From the spectroscopic data, a prospect of using the $D$-fine structure levels as a qubit for the quantum information processing is reviewed.

• Received 8 August 2007

DOI:https://doi.org/10.1103/PhysRevA.77.012508