Phase-locked light sources with low-phase noise for manipulating terahertz-separated metastable states in 40Ca+

We report the development of phase-locked light sources for manipulating terahertz-separated metastable states in ⁴⁰Ca⁺. Two Ti:sapphire lasers with frequencies separated by 1.82 THz are phase-locked using an optical comb generator. The obtained phase noise is 49.8 mrad when the phase-locked loop is closed. Using the developed light sources, we excite Rabi oscillations between the terahertz-separated 3²D_3/2 and 3²D_5/2 states in ⁴⁰Ca⁺. We discuss the phase noises of the light sources and their effect on excitation of Rabi oscillations.