Enhancement of magnon-magnon entanglement in cavity magnomechanics with an optical parametric amplifier

A scheme to enhance the entanglement between two magnon modes by an optical parametric amplifier (OPA) in a cavity magnomechanical system composed of a microwave cavity mode, two magnon modes and a mechanical mode is proposed. Owing to the magnon-phonon and cavity-magnon couplings, the enhancement of magnon-magnon entanglement can be realized in the presence of OPA with optimal phase by entanglement transfer. Especially, in virtue of the OPA, the strong entangled state for the two magnon modes can be prepared when there is no magnon-phonon interaction. Moreover, the improvement of tripartite entanglement between cavity-magnon-magnon with assistance of the OPA is also taken into account and analyzed. It is noted that the OPA increases the robustness of both magnon-magnon entanglement and cavity-magnon-magnon entanglement against the environmental temperature