Macroscopic entanglement of three magnon modes in three cavities via optical parametric amplifier

We propose a scheme to generate bipartite and tripartite entanglements of three magnon modes in a three-cavity system using a nonlinear optical parametric amplifier (OPA). The three magnon modes in three YIG spheres are respectively placed inside three cavities near the maximum magnetic fields of the cavities and coupled to cavity modes via linear magnetic dipole interaction. Additionally, linear coupling interaction exists between two cavities. Using experimentally feasible parameters, we demonstrate that OPA can prepare these three magnon modes in a steady-state entangled state, bipartite and tripartite entanglements generally increase with the nonlinear interaction strength of OPA. An alternative approach to enhance quantum entanglement involves multiplexed OPA inputs. By employing individual OPA for each cavity, we observe a significant improvement in entanglement generation. All the entanglements are robust against bath temperature.