2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/94089The new process of quantum-injection into an optical parametric amplifier operating in entangled configuration is adopted to amplify into a large dimensionality spin 1/2 Hilbert space the quantum entanglement and superposition properties of the photon-couples generated by parametric down-conversion. The structure of the Wigner function and of the field's correlation functions shows a decoherence-free, multiphoton Schroedinger-cat behaviour of the emitted field which is largely detectable against the squeezed-vacuum noise. Furthermore, owing to its entanglement character, the system is found to exhibit multi-particle quantum nonseparability and Bell-type nonlocality properties. These relevant quantum features are analyzed for several travelling-wave optical configurations implying different input quantum-injection schemes25 pages, 5 figures, submitted to Phys. Rev. AQuantum Physicstext