Unconventional Magnon Blockade in Anti‐PT‐Symmetric Cavity Magnonics System

This is the authors' abstract. We don't add key points for this paper.

We focus on the magnon blockade phenomenon in a non‐Hermitian cavity magnonics system with dissipative magnon–photon coupling. The system consists of a cross‐shaped microwave circuit supporting both standing and traveling waves and a yttrium iron garnet sphere supporting a magnon mode, where the dissipative coupling between the magnon mode and the standing wave cavity mode is caused by the traveling wave, forming the non‐Hermitian cavity magnonics system. For the non‐Hermitian system with the pure dissipative coupling, we find that, by driving the microwave cavity mode using the two‐photon driving field, the magnon blockade phenomenon can occur due to the destructive interference of the transition paths. More excitingly, when the non‐Hermitian cavity magnonics system is set as an anti‐parity‐time ()‐symmetry system, the optimal magnon blockade phenomenon occurs near the exceptional points (transition points from the unbroken‐ to broken‐anti‐ symmetry). Then we analyze the influence of the driving strength on the magnon blockade, and give the optimal driving strength. The presented work not only provides an alternative method for the magnon blockade, but also can promote the study of the quantum effects in the non‐Hermitian cavity magnonics system.