Magnon blockade and entanglement in a hybrid magnon-photon-phonon-SQ system

We investigate a hybrid optomagnonic system consisting of a lossy microwave cavity coupled to a mirror, hosting a superconducting qubit (SQ) and a yttrium–iron–garnet (YIG) sphere. The system features indirect magnon–SQ interactions mediated by cavity fields, while the cavity field directly couples to magnons, the SQ, and phonons. By deriving an effective Hamiltonian and solving the Lindblad master equation (under dissipative conditions), we analyze magnon blockade, entanglement dynamics between the magnon and other constituent parts of the system, as well as the magnon fidelity over time. Variations in photon–phonon and photon–magnon coupling strengths reveal that stronger photon–magnon coupling amplifies magnon blockade, generating pronounced non-classical signatures. Further investigations on photon–phonon coupling, photon–SQ coupling, magnon/phonon dissipation, and phonon frequency demonstrate that photon–phonon interactions and magnon dissipation critically enhance steady-state as well as time-dependent entanglement between magnons, photons, and phonons. Reducing phonon dissipation, tuning phonon frequency, and increasing photon–phonon/magnon couplings effectively improve entanglement robustness across both transient and equilibrium regimes. Finally, phonon dissipation on the magnon fidelity is presented, highlighting the system potential for high-precision quantum state control. These results provide comprehensive insights into optimizing quantum correlations and coherence in hybrid optomagnonic platforms for quantum information applications.