  Using a rigorous quantum model a comprehensive study of physical properties
of entangled photon pairs generated in spontaneous parametric down-conversion
in chirped periodically-poled crystals is presented. Spectral, temporal, as
well as spatial characteristics of photon pairs are analyzed. Spectral
bandwidths, photon-pair flux, and entanglement area can be effectively
controlled by chirping. Quantification of entanglement between photons in a
pair is given. Splitting of entanglement area in the transverse plane
accompanied by spectral splitting has been revealed. Using the model
temperature dependencies of the experimental intensity profiles reported in
literature have been explained.
