Manipulation Of Tripartite Frequency Correlation Under Extended Phase Matchings

We investigate how to manipulate the tripartite frequency correlation of triplets which are generated from cascaded spontaneous parametric down-conversions. A monolithic quadratic nonlinear crystal is designed to contain two segments of periodically poled lithium niobate waveguide as nonlinear mediums to produce cascaded photon pairs both under phase-matching and group-velocity-matching conditions. By choosing proper pump bandwidth and crystal length, the tripartite frequency will show a full correlation, partial correlation, or no correlation, corresponding an inseparable triplet, separable one photon and biphoton, or three separable photons, respectively. This opens up a way to manipulate the tripartite correlation, which is important for understanding quantum fundamentals and also can supply key elements for developing new quantum technologies.