Quantum dynamics and statistics of two coupled down-conversion processes

In the framework of the Heisenberg-Langevin theory the dynamical and statis tical effects arising from a mutual interaction of two non-degenerate down- conversion processes are investigated. Primarily, we focus on the possibili ty of controlling the intensity and statistical properties of the light gen erated in one nonlinear medium by the light entering the other one. Apart f rom this all-optical switching, behaviour reminiscent of the Zeno and anti- Zeno effects is examined. We also show that the model discussed is an inter esting generalization of the famous experiments by Zou er al (Zou X Y, Wang L J and Mandel L 1991 Phys. Rev. Lett. 67 318) on induced coherence withou t induced emission.