  We study the remote entanglement generation between macroscopic microwave
magnon modes in a coupled cavity system. The cavities are connected via an
optical fiber, which necessitates the use of a frequency conversion inside the
cavity. The converter may be implemented via a rare-earth doped crystal acting
like an effective three-level system. The entanglement dynamics of the system
is analytically studied, and an active optimal control method is also proposed
where one may generate maximally entangled Bell states on demand with a given
evolution time. The system dynamics and its control have also been studied in a
generic non-Markovian open system framework, and the generated entanglement is
found to be robust against environmental noises.
