Entanglement and asymmetric quantum steering in a nonlinear cavity-magnon system with two-fold periodic amplitude modulation

Abstract We show how robust magnon-magnon (or photon-magnon) entanglement and asymmetric quantum steering can be achieved in a nonlinear cavity-magnon system composed of a microwave cavity and two yttrium-iron-garnet (YIG) spheres, which are each driven by external microwave driving fields. The self-Kerr nonlinearity (SKN) of two magnons drives this behaviour and we study how two-fold periodically-modulated driving fields influence the system dynamics. We find that beating occurs both in the classical average of the cavity mode and in the entanglement between modes. Moreover, the use of modulated driving fields can enhance the degree of entanglement generated as well as giving rise to asymmetric quantum steering effects that would not otherwise be present. Finally, we show that the entanglement generated this way has improved robustness to thermal noise opening the way to potential applications of magnon-based hybrid systems in quantum information processing and studies of fundamental physics.