  We examine the passage of ultracold two-level atoms through two separated
laser fields for the nonresonant case. We show that implications of the atomic
quantized motion change dramatically the behavior of the interference fringes
compared to the semiclassical description of this optical Ramsey
interferometer. Using two-channel recurrence relations we are able to express
the double-laser scattering amplitudes by means of the single-laser ones and to
give explicit analytical results. When considering slower and slower atoms, the
transmission probability of the system changes considerably from an
interference behavior to a regime where scattering resonances prevail. This may
be understood in terms of different families of trajectories that dominate the
overall transmission probability in the weak field or in the strong field
limit.
