Role of Optical and Magnonic Parametric Amplifications in Enhancing Nonclassicality in a Dissipative Microcavity Magnonic System Including Kerr Media

Nonclassical states of quantized light are essential resources for quantum information science and emerging quantum technologies. In this work, we investigate the generation of such states in a dissipative hybrid system, namely a microcavity consisting of a ferromagnetic yttrium iron garnet (YIG) sphere coupled to a quantized microwave cavity mode, and particularly incorporating several nonlinear quantum optical elements including various Kerr media, optical parametric amplifier (OPA), and a magnonic parametric amplifier (MPA) which is introduced as the magnonic analog of the OPA. Decoherence effects arise from thermal photonic and magnonic reservoirs. Using the Heisenberg–Langevin formalism, we analyze the influence of Kerr nonlinearities, OPA, and MPA on several nonclassical signatures, including antibunching, entanglement, quadrature squeezing, and violation of the Cauchy–Schwarz inequality. Numerical results show that photon and magnon antibunching, as well as violation of the Cauchy–Schwarz inequality, can persist even in the presence of considerable dissipation, although these effects weaken as the thermal photon and magnon populations increase. In contrast, entanglement and quadrature squeezing remain remarkably robust against thermal noise. Furthermore, we demonstrate that the inclusion of OPA and MPA generally enhances all investigated nonclassical effects, whereas Kerr nonlinearities have negligible influence within the considered parameter regimes.