We theoretically investigate the quantum coherence and its nonreciprocity in a cavity magnomechanical system composed of a spinning microwave resonant cavity and an yttrium iron garnet sphere. The optical Fizeau shift related to the driving direction of the microwave cavity is responsible for an important source of nonreciprocity in the stability of the system, which leads to the nonreciprocal quantum coherence. Remarkably, the quantum coherence of the mechanical motion mode can be greater than that of the microwave photon and the magnon modes, which describes a significant enhancement of the correlations of the system. We also analyze in detail the influence of the strength of the magnomechanical coupling, the Kerr nonlinearity, and the effective detunings on the quantum coherence. Our paper paves the way for optimizing the stability range of coupled systems and maintaining more reliable quantum coherence by designing and modulating the system parameters in cavity magnetomechanical systems.
We theoretically investigate the quantum coherence and its nonreciprocity in a cavity magnomechanical system composed of a spinning microwave resonant cavity and an yttrium iron garnet sphere. The optical Fizeau shift related to the driving direction of the microwave cavity is responsible for an important source of nonreciprocity in the stability of the system, which leads to the nonreciprocal quantum coherence. Remarkably, the quantum coherence of the mechanical motion mode can be greater than that of the microwave photon and the magnon modes, which describes a significant enhancement of the correlations of the system. We also analyze in detail the influence of the strength of the magnomechanical coupling, the Kerr nonlinearity, and the effective detunings on the quantum coherence. Our paper paves the way for optimizing the stability range of coupled systems and maintaining more reliable quantum coherence by designing and modulating the system parameters in cavity magnetomechanical systems.
We theoretically investigate the quantum coherence ans its nonreciprocity in a cavity magnomechanical (CMM) syetem, which consists of a rotating yittrium iron garnet (YIG) sphere and a microwave cavity. By adjusting the direction of the magnetic field, the frequency shift of a magnon mode can be tuned from positive to negative due to the Barnett effect. This effect leads to a significant difference in the system stability and is responsible for the nonreciprocal quantum coherence. We examine how the input power, magnomechanical and magnon-photon coupling rates, decay rates of both the cavity photon modes and the magnon modes influence the quantum coherence. Through careful tuning of system parameters, nearly perfect nonreciprocity can be achieved. Our results provide a controllable mechanism for direction-dependent quantum coherence, with potential applications in nonreciprocal quantum devices and information processing.
We propose a scheme to create nonreciprocal entanglement in a spinning cavity magnomechanical system. The setup comprises a whispering gallery mode resonator with two counterpropagating modes, simultaneously coupled to yttrium iron garnet. By spinning the resonator, the counterpropagating modes undergo an opposite Fizeau drag caused by the optical Sagnac effect. We show that in a spinning resonator, the cavity-magnon-phonon modes get entangled along a chosen direction while remaining fully uncorrelated in the other. The degree of nonreciprocity is determined by the drive detuning and the spinning velocity of the resonator. Our work provides a different route to achieve chiral control of quantum entanglement involving magnon-photon-phonon modes.
Abstract A scheme is proposed for generating and enhancing stable nonreciprocal entanglement in a spinning cavity magnomechanical system. The key components of this scheme include a ferromagnetic yttrium iron garnet sphere and a whispering gallery mode resonator supporting two counter‐propagating modes. To further optimize the performance of the system, a coherent feedback loop is introduced to reinject the dissipated energy back into the system. This not only provides an additional coupling path for the system but also effectively avoids introducing additional noise caused by measurement. The design significantly enhances both bipartite entanglement and genuine tripartite entanglement. Meanwhile, by spinning the resonator, the cavity modes experience Fizeau drag due to the optical Sagnac effect, thereby achieving nonreciprocal entanglement, which is crucial for applications such as unidirectional quantum communication channels. Additionally, the research demonstrates that even in the presence of backscattering, the entangled state can still recover significantly, highlighting the robustness of entanglement under photon backscattering. This work provides an effective method to enhance and protect quantum resources and holds important application potential for applications in quantum information processing based on magnonics.
We propose a theoretical scheme for the generation of nonreciprocal multipartite entanglement in a two-mode cavity magnomechanical system, consisting of two cross-microwave (MW) cavities having a yttrium iron garnet (YIG) sphere, which is coupled through magnetic dipole interaction. Our results show that the self-Kerr effect of magnon can significantly enhance multipartite entanglement, which turns out to be nonreciprocal when the magnetic field is tuned along the crystallographic axis [110]. This is due to the frequency shift on the magnons (YIG sphere), which depends on the direction of the magnetic field. Interestingly, the degree of nonreciprocity of bipartite entanglements depends upon a careful optimal choice of system parameters like normalized cavity detunings, bipartite nonlinear index, self-Kerr coefficient, and effective magnomechanical coupling rate G. In addition to bipartite entanglement, we also present the idea of a bidirectional contrast ratio, which quantifies the nonreciprocity in tripartite entanglements. Our present theoretical proposal for nonreciprocity in multipartite entanglement may find applications in diverse engineering nonreciprocal devices
We investigate theoretically macroscopic quantum coherence and tripartite entanglement in a three-mode magnomechanical system with a yttrium iron garnet sphere, which is simultaneously driven by a magnetic pump and a microwave field pump to establish an effective magnomechanical coupling. We discuss mainly the dependence of quantum properties on the driving power, the cavity field detuning and decay, the magnomechanical coupling strength, the bias magnetic field, and the temperature of an environment. It is found that the quantum coherence of the system can be attained easily in a large range of parameters. In contrast, tripartite photon-magnon-phonon entanglement can only be realized in a relatively small range of optical and magnetic parameters. In particular, the quantum coherence of the mechanical mode can be larger than that of the photon and magnon modes, which means that the environmental incoherence of the mechanical mode in the cavity magnomechanical system can be suppressed significantly. These results may help manipulate simultaneously the macroscopic quantum coherence and the tripartite entanglement of massive objects in coupled magnomechanical system, which may have potential applications for realizing highly tunable information processing through the flexible control of quantum properties.
We theoretically propose a cavity magnomechanical system with a levitated yttrium iron garnet sphere to study the entanglement characteristics between subsystems. The system consists of microwave photon, magnon, and mechanical phonon modes, where the photon and magnon modes can be driven by external microwave sources. We find that with the appropriate choice of the suspension position, the effective couplings between the cavity field and the magnon and phonon modes can be established, thus inducing the generation of bipartite entanglement and genuine tripartite entanglement in the system. Further, we also analyze in detail the influences of the radius of the sphere, the detunings of the cavity and magnon modes, the driving power, the frequency of the phonon mode, and the environment temperature on the characteristics of the quantum entanglement. The results obtained here indicate that the bipartite and tripartite entanglements can be manipulated by changing the radius and the oscillation frequency of the sphere in addition to changing the parameters of the cavity field, and therefore, the levitated magnomechanical system has a potential application in the study of macroscopic quantum phenomena.