Matched ultraslow propagation of highly efficient four-wave mixing in a closely cycled double-ladder system

We present a fully time dependent, adiabatic solution, and steady-state analysis for the ultraslow propagation of the nondegenerate four-wave mixing NDFWM signal and the weak probe beam in a closely-cycled double-ladder system. Under appropriate especially power balance conditions, the two-mode probe and phase-matched NDFWM pulses, after a characteristic propagation length, evolve into a pair of amplitude and group velocity matched pulses. Double transparency for the probe and NDFWM beams can be achieved owing to an efficient oneand three-photon destructive interference involving the NDFWM beam and its back reaction to the probe beam. The forward and backward configurations are investigated in this double-ladder system, and their efficiencies are calculated and compared.