We investigate how tailoring the phase of the optical field allows us to select the different routes induced by time-delayed femtosecond pulse pairs exciting a two-photon transition in rubidium atoms. It is shown that by introducing an external phase in one of the pulses, the pathways leading to optical interferences can be eliminated, leaving only the quantum interferences.

• Received 14 July 2006

DOI:https://doi.org/10.1103/PhysRevA.74.055402