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We study the slow-fast light effect and multi-transparency induced by magnomechanical systems. The system incorporates two magnons, which are collective magnetic excitations, placed alongside a degenerate optical parametric amplifier (OPA) within a cavity. The interaction between phonons, magnons, and light inside the cavity leads to two phenomena: magnomechanically induced transparency (MMIT) and magnon induced transparency (MIT). We show how an OPA alters the absorption and dispersion characteristics of the light spectrum. The observation of the Fano resonance through magnon-mechanical coupling with the degenerate OPA is discussed. Through tuning vibration interactions and the OPA, we achieve the improvement of slow light. We hope our findings could pave the way for advancements in quantum information processing.

The connections between thermodynamics and quantum information processing are of paramount importance. Here, we address a bipartite entanglement via extracted work in a cavity magnomechanical system contained inside an yttrium iron garnet (YIG) sphere. The photons and magnons interact through an interaction between magnetic dipoles. A magnetostrictive interaction, analogous to radiation pressure, couple's phonons and magnons. The extracted work was obtained through a device similar to the Szil\'ard engine. This engine operates by manipulating the photon-magnon as a bipartite quantum state. We employ logarithmic negativity to measure the amount of entanglement between photon and magnon modes in steady and dynamical states. We explore the extracted work, separable work, and maximum work for squeezed thermal states. We investigate the amount of work extracted from a bipartite quantum state, which can potentially determine the degree of entanglement present in that state. Numerical studies show that entanglement, as detected by the extracted work and quantified by logarithmic negativity, is in good agreement. We show the reduction of extracted work by a second measurement compared to a single measurement. Also, the efficiency of the Szilard engine in steady and dynamical states is investigated. We hope this work is of paramount importance in quantum information processing.

In this article, we investigate the hierarchy of quantum correlations between two gravitational cats states (modeled by two qubits). We use concurrence to quantify the entanglement between the two gravitational cat states. Quantum steering is employed to measure the steerabilities. We consider geometric quantum discord to quantify quantum correlations beyond entanglement. We show that the concurrence persists even when steerability is lost under thermal effects. We also show that the temperature influences the degree of quantum correlations between the two gravitational cat states. Besides, when the energy difference between the ground state and the first excited level becomes significant, the states become separable.