Abstract It belongs to a hot topic to sense or detect the weak and even ultra-weak physical quantities by utilizing quantum platforms and methods. We here propose a hybrid magnon-photon system of the yttrium iron garnet (YIG) magnon mode coupled to a microwave cavity, which also includes another degree of freedom with respect to the thermal vibration of this YIG microsphere. In this quasi-tripartite coupling system, we generalize the condition for satisfying energy degeneracy and anti-crossing behaviors. Especially around the zero-energy area, we can get the joint quantum effects of anti-crossing behavior and degeneracy of systemic energy, and then reach a significantly enhanced sensitivity to this phase disturbance. Therefore our proposal can characterize this weak vibration through a phase disturbance and indicate a group of clearly resolvable output spectra. This investigation may be considered as an encouraging attempt on sensing weak quantity by engineering the systemic energy into the critical area for further enlarging its sensitivity to the weak disturbance.
Abstract It belongs to a hot topic to sense or detect the weak and even ultra-weak physical quantities by utilizing quantum platforms and methods. We here propose a hybrid magnon-photon system of the yttrium iron garnet (YIG) magnon mode coupled to a microwave cavity, which also includes another degree of freedom with respect to the thermal vibration of this YIG microsphere. In this quasi-tripartite coupling system, we generalize the condition for satisfying energy degeneracy and anti-crossing behaviors. Especially around the zero-energy area, we can get the joint quantum effects of anti-crossing behavior and degeneracy of systemic energy, and then reach a significantly enhanced sensitivity to this phase disturbance. Therefore our proposal can characterize this weak vibration through a phase disturbance and indicate a group of clearly resolvable output spectra. This investigation may be considered as an encouraging attempt on sensing weak quantity by engineering the systemic energy into the critical area for further enlarging its sensitivity to the weak disturbance.
We present a quantum theoretical framework that describes the simultaneous emergence of magnon- and photon lasing in a tripartite hybrid solid-state platform. The system integrates optically pumped nitrogen-vacancy (NV) centers, a magnetic yttrium-iron-garnet (YIG) microsphere, and a microwave (MW) cavity. Through a comprehensive analysis of the system's dynamics, we reveal the cooperative interactions that drive coherent-stimulated emission in both the magnonic (spin-wave) and photonic (electromagnetic) domains. The model outlines a scalable configuration in which NV centers, excited via optical pumping, couple efficiently to the magnon modes of the YIG sphere placed inside the microwave cavity. Numerical simulations based on experimentally accessible parameters confirm the feasibility of dual-domain lasing. This work advances the integration of photonic and magnonic platforms, opening new opportunities for quantum-enhanced sensing, low-power spintronics, and on-chip quantum information processing.
We propose an alternative scheme to achieve the cross-correlations between magnon and photon in a hybrid nonlinear system including two microwave cavities and one yttrium iron garnet (YIG) sphere, where two cavities nonlinearly interact and meanwhile one of cavities couples to magnon representing the collective excitation in YIG sphere via magnetic dipole interaction. Based on dispersive couplings between two cavities and between one cavity and magnon with the larger detunings, the nonlinear interaction occurs between the other cavity and magnon, which plays a crucial role in generating quantum correlations. By analyzing the second-order correlation functions via numerical simulations and analytical calculations, the remarkable nonclassical correlations are existent in such a system, where the magnon blockade and photon antibunching could be obtainable on demand. The scheme we present is focused on the magnon-photon cross-correlations in the weak coupling regime and relaxes the requirements of experimental conditions, which may have potential applications in quantum information processing in the hybrid system.
We present a proposal to produce bipartite and tripartite entanglement in a hybrid magnon cavity QED system. Two macroscopic yttrium iron garnet (YIG) spheres are coupled to a single-mode microwave cavity, where the cavity photons are generated via a two-photon process induced by a strong pump field. Using mean-field theory, we show that nonlinear pumping can result in strong bipartite entanglement between the cavity photon and magnon under two conditions, i.e., ${\ensuremath{\delta}}_{c}{\ensuremath{\delta}}_{m}=2{g}^{2}$ and ${\ensuremath{\delta}}_{c}=\ensuremath{-}{\ensuremath{\delta}}_{m}$. For the latter one, we also show the possibility for producing bipartite entanglement between two magnon modes as well as tripartite entanglement among three modes. Combining these two conditions, we further derive a third condition, i.e., ${\ensuremath{\delta}}_{m}^{2}\ensuremath{-}{\ensuremath{\phi}}^{2}+2{g}^{2}=0$, where tripartite entanglement can be achieved when two magnon modes have different resonant frequencies.
Photonic spin Hall effect in PT-symmetric non-Hermitian cavity magnomechanics
Non-Hermitian cavity magnomechanics (CMM), which incorporates the magnon-photon and magnon-phonon interactions simultaneously, enables rich physical phenomena, including exceptional-point-enhanced sensing, and offers pathways toward topological transitions and nonreciprocal quantum transformation. These interactions exert a pivotal influence on the optical response of a weak probe field and pave the way for novel applications in quantum technologies. In this work, we consider a yttrium-iron-garnet (YIG) sphere coupled to a microwave cavity. The magnon mode of the YIG sphere is directly excited through microwave field coupling, whereas the cavity mode is probed via a weak-field interrogation scheme. The direct interaction of a traveling field with the magnon mode induces gain in the system, thereby establishing non-Hermitian dynamics. The parity-time (PT)-symmetric behavior of a hybrid non-Hermitian CMM is designed and investigated. Eigenvalue spectrum analysis demonstrates that a third-order exceptional point (EP_3) emerges under tunable effective magnon-photon coupling when the traveling field is oriented at an angle of π/2 relative to the cavity's x-axis. The photonic spin Hall effect (PSHE) in a reflected probe field is subsequently examined in such a system. Under balanced gain and loss conditions and in the presence of effective magnon-phonon coupling, tunable effective magnon-photon coupling enables coherent control of the PSHE across the broken PT-symmetric phase, at the EP_3, and in the PT-symmetric phase. Investigation reveals that the PSHE can be significantly enhanced or suppressed via effective magnon-photon coupling. The influence of intracavity length on the PSHE is further explored, providing an additional parameter for fine-tuning the transverse shift. These findings establish a direct correspondence between the PSHE and the underlying non-Hermitian eigenvalue spectrum.
Abstract We propose to realize bipartite and tripartite entanglements transfer in a cavity magnomechanical system consisting of a microwave cavity with an yttrium iron garnet (YIG) sphere and a silicon-nitride membrane in it. The initial magnon–YIG phonon entanglement and photon-membrane phonon entanglement caused by the magnetostrictive interaction and the optomechanical interaction can be effectively transferred to magnon–membrane phonon entanglement and photon–YIG phonon entanglement. Photon–magnon–YIG phonon and photon–magnon–membrane phonon entanglements can also be realized in the system. These two types of tripartite entanglements can be easily transferred from one type to the other by adjusting the detuning or dissipation ratio. Moreover, the bipartite and tripartite entanglements and their transfer are all robust against temperature. Furthermore, by introducing supermodes formed by the photon and magnon modes, we find that the entanglement between the two mechanical modes can be obtained under the condition of an extremely low temperature. And the effective detuning region of the YIG phonon-membrane phonon entanglement is complementary to the detuning regions of other bipartite entanglements. Our results indicate that the combination of cavity magnomechanical and optomechanical systems could provide more flexible controllability of bipartite and tripartite entanglements and their transfer and could serve as a potential quantum interface among microwave, magnon, and mechanical systems.
We propose a scheme to generate magnon-induced absorption (MIA) in a two-cavity magnonics system. By placing an yttrium iron garnet (YIG) sphere into one of two coupled microwave cavities, three different interference pathways are established by the photon coupling and magnon-photon coupling, leading to the conversion from suppression to enhancement on resonance under proper conditions. Most interestingly, the analytical results of the probe absorption are solved based on bright and dark modes in a dressed-state picture, which can be used to explain the position, width, and height of the absorption peaks accurately. Furthermore, we investigate the noise spectral density (NSD) of the microwave cavity and find out the similar MIA phenomena, which may provide a feasible way to remotely detect a magnon with an optical method.