Dissipation-induced magnon-photon entanglement in a squeezed vacuum reservoir

Dissipation usually has negative effects on magnon-photon entanglement and thus is engineered to a low level in many works. In this work, we propose a theoretical scheme to generate steady-state magnon-photon entanglement by using the dissipatively coupled magnon and photon in a squeezed vacuum reservoir. It is found that the reservoir-mediated magnon-photon coupling and the squeezing nature of reservoir result in the entanglement. As the coupling strength increases or intrinsic dissipation decreases, the magnon-photon correlation and entanglement can be enhanced. As the squeezing amplitude $r$ of reservoir increases, the logarithmic negativity, which is the measure of entanglement, presents a maximum at an optimal value of $r$. This reflects the competition between the enhancement of magnon-photon correlation which favors the entanglement, and the increase in the input noise which destroys the entanglement. We also propose a device geometry which could be realized with existing technology of cavity magnon polariton and superconducting Josephson parametric amplifiers. Our theoretical methods and results may be useful for future theoretical studies of magnon-photon or magnon-magnon entanglement and experimental studies of magnon-based quantum communication and manipulations.