  Two-photon time-frequency entanglement is a valuable resource in quantum
information. Resolving the wavepacket of ultrashort pulsed single-photons,
however, is a challenge. Here, we demonstrate remote spectral shaping of single
photon states and probe the coherence properties of two-photon quantum
correlations in the time-frequency domain, using engineered parametric
down-conversion (PDC) and a quantum pulse gate (QPG) in nonlinear waveguides.
Through tailoring the joint spectral amplitude function of our PDC source we
control the temporal mode structure between the generated photon pairs and show
remote state-projections over a range of time-frequency mode superpositions.
