Phase-coherent multilevel two-photon transitions in cold Ph atoms: Ultrahigh-resolution spectroscopy via frequency-stabilized femtosecond laser - art. no. 011402

A two-photon transition in cold Rb atoms will be probed with a phase-cohere nt wide bandwidth femtosecond laser comb. Frequency domain analysis yields a high-resolution picture where phase coherence among various transition pa thways through different intermediate states produces interference effects on the resonantly enhanced transition probability. This result is supported by the time domain Ramsey interference effect. The two-photon transition s pectrum is analyzed in terms of the pulse repetition rate and carrier frequ ency offset, leading to a cold-atom-based frequency stabilization scheme fo r both degrees of freedom of the femtosecond laser.