Macroscopic entanglement generation and transfer in a coupled cavity–magnon system via optical parametric amplifier

Abstract

Generation and transfer of quantum entanglement at macroscopic scales are key for advancing quantum information processing and communication. This paper presents a theoretical framework for achieving and transferring bipartite and tripartite entanglement in a coupled cavity–magnon system integrated with an optical parametric amplifier (OPA). The findings indicate that in the four-mode system under study, the nonlinear gain introduced by the OPA facilitates the creation of bipartite entanglement. This bipartite entanglement, produced by two coupled microwave cavities, is driven concurrently by the squeezing effects of the OPA and transferred to two magnons through cavity–magnon coupling. The transfer rate of this entanglement increases with the strength of the linear cavity–magnon coupling and approaches unity. The magnon–magnon entanglement produced can be tuned using parameters such as the cavity–cavity coupling strength, the cavity dissipation rate, and the nonlinear gain coefficient of the OPA. Additionally, this entanglement shows robustness to temperature. Under steady-state conditions, the system achieves tripartite entanglement in both cavity–magnon–cavity and magnon–cavity–magnon configurations, and the OPA nonlinear effects improve the system's resilience to temperature fluctuations.