Entangling a Magnon and an Atomic Ensemble Mediated by an Optical Cavity

We propose a scheme to entangle a magnon in an yttrium iron garnet sphere with an atomic ensemble by using an optical cavity as the qubus. The cavity mode couples with the magnon through magnetic dipole interaction, and simultaneously couples with the atomic ensemble through Jaynes-Cummings interaction. Moreover, the magnon couples with the mechanical vibration mode of the yttrium iron garnet sphere via magnetostrictive interaction. In this hybrid system, we find that there exist six kinds of bipartite entanglements, including the entanglement between the magnon and the atomic ensemble, and we use logarithmic negativity ${E}_{N}$ for quantification. Our findings demonstrate the phenomena of entanglement sudden death, entanglement sudden revival, and entanglement transfer among the six bipartite entanglements. Then we focus on entanglement between a magnon and an atomic ensemble, and we show that the entanglement can be effectively enhanced by increase of the magnetic dipole coupling or the magnetostrictive coupling. Finally, we discuss the robustness and find that incorporating an atomic ensemble into the system could enhance the steady-state entanglement's tolerance to the environmental temperature.