Dissipative-coupling-induced steady-state entanglement and one-way steering in a cavity-magnonics system

In the cavity-magnonics system, the coupling between microwave photon and magnon is of beam-splitter (BS) interaction, which in general does not support steady-state entanglement in a vacuum environment. We propose a scheme to generate and enhance steady-state magnon-photon entanglement and one-way steering in cavity-magnonics system. By coupling microwave cavity mode and magnon mode to a common waveguide, the effective dissipative coupling of the cavity-magnonics system is derived. If there is only nondegenerate parametric (NP) dissipative coupling, entanglement is negatively affected by the effective gain of the cavity mode caused by the common waveguide environment. When the coherent coupling exists, effective gain of cavity mode can cancel the intrinsic dissipation. Consequently, the larger the intrinsic dissipation of cavity the better the entanglement. When the effective dissipative coupling with NP and BS coexist, the effective dissipation can be eliminated and the entanglement is significantly improved. In addition, we find that the asymmetric coupling of the two modes to the common waveguide leads to one-way steering, which means that the cavity mode can guide the magnetic mode, and the magnetic mode can not affect the cavity mode through local measurements. This property facilitates the development of the cavity-magnonics system towards quantum information processing.