Entangled Field States in the Process of Nondegenerate Parametric Decay in an Optical Cavity

For the process of non-degenerate parametric decay in an optical cavity, where a photon with energy ћω₃ decays into two photons with energies ћω₂ and ћω₁, where ћω₃ = ћω₂ + ћω₁, the possibility of formation of entangled field states in terms of photon number variables between interacting modes of the optical system is investigated. Strong entangled states are shown between the modes with frequencies ω₂ and ω₁ in the case of strong coupling between interacting modes. In the case of weak and very strong coupling between these modes, relatively weak entangled states are formed. In the case of weak coupling, these modes are localized in entangled vacuum states with low values of quantum entropy. For modes with frequencies ω₃ and ω₁etangled states are formed only in the case of strong coupling.