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Advanced Quantum Technologies

Entanglement Enhancement by the Synergistic Effect of Optical Parametric Amplification and Coherent Feedback in Cavity Magnonics

Guoqing Liu, Cheng‐Zhi Gao, Nan Wang, Lin Yu, Ai‐Dong Zhu

Published Jun 10, 2025• 1 citation
Publisher

Abstract

Abstract The scheme is proposed to enhance the entanglement in cavity‐magnonics system by exploiting the synergistic effects of an optical parametric amplifier (OPA) and coherent feedback. In the system, the two cavities are arranged in a cross‐shaped, with a yttrium iron garnet (YIG) sphere positioned near the intersection of the cross‐shaped cavities. By introducing coherent feedback, the energy dissipated by the horizontal cavity can be fed back into the vertical cavity, which can be compensated via OPA. The nonlinear gain of OPA and reflectivity of the coherent feedback play important roles in the dynamics of the system and enable enhancement of both bipartite and tripartite entanglement as compared to the system without OPA and coherent feedback. The robustness of entanglement against environment temperature can also be greatly improved. Moreover, in the system that possesses a symmetrical structure but demonstrates asymmetric energy flow, controllable one‐way steering can be realized through the precise adjustment of specific parameters within the system. The scheme offers a novel approach to realize high‐quality entanglement resources and holds potential applications in quantum information processing and quantum communication.

DOI
10.1002/qute.202500088

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Abstract Two cavity‐magnon subsystems coupled via the two single‐mode cavities mediated by a non‐degenerate parametric down conversion and each cavity carrying a magnon confined in a Yttrium‐iron‐garnet sphere is proposed to study one‐way quantum steering and asymmetric tripartite entanglement. The entanglement can be transferred from the two microwave cavities to the two separated magnon modes using magnetic dipole interaction. Different from previous schemes, the present study demonstrates efficient realization of controllable one‐way quantum steering between two magnon modes through asymmetric frequency detunings of the two magnon modes. In addition, an asymmetric tripartite entanglement can also be achieved. Furthermore, the system exhibits robustness to temperatures up to 100 mK, providing a promising avenue for utilizing cavity magnonics systems in unidirectional transmission of quantum information.