Study On Generation Of The Squeezed States And Quantum Correlation In Cavity Magnomechanical System

Cavity magnomechanical systems,including cavity-magnon system of yttrium iron garnet(YIG),have attracted extensive attention and witnessed magnificent achievement in last decades years due to its high spin density and low damping rate.In parallel with cavity optomechanical systems,cavity magnomechanical systems as a hybrid system consisting of photons,magnons,and phonons,provide an alternative platform to create quantum effects at a macroscopic scale.With the aid of magnetostrictive force,cavity magnomechanical systems can create various novel quantum effects,such as magnon-induced nonreciprocity,ground state cooling of magnomechanical resonator,quadrature squeezing for magnon and phonon,magnon blockade,and quantum entanglement.Besides,hybrid quantum systems involving magnons have committed to implementing high-order sideband generation,ultrasensitive magnetometer,magnon-assisted photon-phonon conversion,exceptional points,and storage and retrieval of quantum states.These studies prompt us to further explore novel quantum effects based on the cavity magnomechanical systems.In this paper,we firstly give the quadratic quantization of the magnons in YIG,and interaction forms between distinct modes in the cavity magnomechanical systems.Subsequently,the conception of the squeezed states is introduced from the aspect of quadrature variances,and the significance of the squeezed states is clarified.Moreover,based on a generic cavity magnomechanical system,we mainly investigate the generation and transfer of the squeezed states,and quantum entanglement and one-way steering between distinct mode pairs.The specific research contents are as follows:Initially,we propose a scheme to generate squeezed states of magnon and phonon modes and verify squeezing transfer between different modes of distinct frequencies in a cavity magnomechanical system which is composed of a microwave cavity and a yttrium iron garnet sphere.In the scheme,by activating the magnetostrictive force in the ferrimagnet,realized by driving the magnon mode with red-detuned and blue-detuned microwave fields,the driven magnon mode can be prepared in a squeezed state.Moreover,the squeezing can be transferred to the cavity mode via the cavity-magnon beam-splitter interaction with strong magnomechanical coupling.Under the weak coupling regime,strong mechanical squeezing of phonon mode can be achieved,which verifies that the scheme can find the existence of quantum effects at macroscopic scales.It is worth emphasizing that,distinct parameter regimes for obtaining strong squeezing of the magnons and phonons are given.Furthermore,the considered scheme can be extended to hybrid optical systems,and can facilitate the advancement for realization of strong mechanical squeezing in cavity magnomechanical systems.Secondly,we propose a scheme to investigate quantum entanglement and one-way steering between distinct mode pairs based on a cavity magnomechanical system composed of a microwave cavity and a yttrium iron garnet sphere.In the scheme,the cavity mode is first squeezed by a weak squeezed vacuum field pumping the microwave cavity,which plays an important role for establishing quantum entanglement and steering.It is found that when the magnon mode is driven by the red-detuned laser,the maximum entanglement between cavity mode and phonon mode and the maximum phonon-to-photon one-way steering can be effectively generated via adjusting the ratio of two coupling rates.While under the much weaker magnomechanical coupling,the quantum entanglement and one-way steering between cavity mode and magnon mode can be achieved,where the steering direction is determined merely by the relative dissipation strength of the cavity to the magnon mode.Furthermore,we reveal that the robustness to the temperature for entanglement and steering between any mode pairs can be evidently enhanced by appropriately selecting the squeezing parameter.