Phase-modulated shaping of narrowband type-I parametric down-converted   photons
  We present a general theoretical description of the temporal shaping of narrowband noncollinear type-I down-converted photons using a spectral phase filter with a symmetric phase distribution. By manipulating the spectral phase of the signal or idler photon, we demonstrate control of the correlation time and shape of the two-photon wave function with modulation frequency and modulation depth of the phase distribution. 
A T Joseph1, R Andrews1, E R Pike2 and S Sarkar2