  Optical signals obtained by the material response to classical laser fields
are given by nonlinear response functions which can be expressed by sums over
various quantum pathways of matter. We show that some pathways can be selected
by using nonclassical fields, through the entanglement of photon and material
pathways, which results in a different-power law dependence on the incoming
field intensity. Spectrally overlapping stimulated Raman scattering (SRS) and
two-photon-absorption (TPA) pathways in a pump probe experiment are separated
by controlling the degree of entanglement of pairs of incoming photons.
Pathway-selectivity opens up new avenues for mapping photon into material
entanglement. New material information, otherwise erased by interferences among
pathways, is revealed.
