  Hybrid systems that combine spin ensembles and superconducting circuits
provide a promising platform for implementing quantum information processing.
We propose a non-Hermitian magnoncircuit-QED hybrid model consisting of two
cavities and an yttrium iron garnet (YIG) sphere placed in one of the cavities.
Abundant exceptional points (EPs), parity-time (PT )-symmetry phases and PT
-symmetry broken phases are investigated in the parameter space. Tripartite
highdimensional entangled states can be generated steadily among modes of the
magnon and photons in PT -symmetry broken phases, corresponding to which the
stable quantum coherence exists. Results show that the tripartite
high-dimensional entangled state is robust against the dissipation of hybrid
system, independent of a certain initial state, and insensitive to the
fluctuation of magnonphoton coupling. Further, we propose to simulate the
hybrid model with an equivalent LCR circuit. This work may provide prospects
for realizing multipartite high-dimensional entangled states in the
magnon-circuit-QED hybrid system.
