We consider regimes of spontaneous parametric down-conversion, both noncollinear and nondegenerate in frequencies. Parameters characterizing degrees of noncollinearity and of nondegeneracy are defined, and they are shown to be not independent of each other. At a given degree of nondegeneracy the emitted photons are shown to propagate along two different cones, the opening angles of which are determined by the degree of nondegeneracy. Based on this, the degree of nondegeneracy can be controlled by means of the angular selection of photons, e.g., with the help of appropriately installed slits. For such selected photons their wave functions are found depending on two frequencies or on two temporal variables. Interference effects arising in such states are tested by analysis of the Hong-Ou-Mandel–type scheme with a varying delay time in one of two channels and with photons from two channels sent to the beamsplitter. The temporal pictures arising after the beamsplitter are found to demonstrate extremely strong interference, exhibiting itself in formation of finite-size temporal combs filled with quantum beats. Parameters of combs depend on the degree of nondegeneracy, and the physical reasons for this dependence are clarified.

• Received 17 May 2018

DOI:https://doi.org/10.1103/PhysRevA.98.013850