Cavity optomagnonics has received considerable research interest in recent years, due to the coherent magnetic Brillioun light scattering in the ferromagnetic material. Here, we theoretically propose and numerically verify a feasible scheme for the full polarization tomography on photon statistics in an optomagnonic whispering-gallery-mode microresonator system in the weak-coupling regime. By performing the polarization pre- and post-selections to manipulate the polarization states of the input and output photons, we find that the rich sub- and super-Poissonian photon statistics can be selectively generated, thanks to quantum interferences. In the parameter space of phase delay, the evolution from photon bunching to antibunching indicates the change from phase to amplitude squeezing. Our obtained result has potential applications in tunable quantum polarized light sources based on the cavity optomagnonic platform in micro-nano scale. It also offers a deeper understanding for full quantum cavity optomagnonics.
Cavity optomagnonics has received considerable research interest in recent years, due to the coherent magnetic Brillioun light scattering in the ferromagnetic material. Here, we theoretically propose and numerically verify a feasible scheme for the full polarization tomography on photon statistics in an optomagnonic whispering-gallery-mode microresonator system in the weak-coupling regime. By performing the polarization pre- and post-selections to manipulate the polarization states of the input and output photons, we find that the rich sub- and super-Poissonian photon statistics can be selectively generated, thanks to quantum interferences. In the parameter space of phase delay, the evolution from photon bunching to antibunching indicates the change from phase to amplitude squeezing. Our obtained result has potential applications in tunable quantum polarized light sources based on the cavity optomagnonic platform in micro-nano scale. It also offers a deeper understanding for full quantum cavity optomagnonics.
We theoretically propose an optical polarization-state engineering based on a cavity optomagnonic platform in the full quantum regime. Here, the optomagnonic interaction can be realized in an yttrium iron garnet (YIG) sphere, which supports both two traveling-photon modes with orthogonal linear polarizations [i.e., horizontally (H-) and vertically (V-) polarized photon modes] and a Kittel magnon mode. In our scheme, the magnons mediate the photons during polarization conversions, and break the time-reversal symmetry in mutual interconversions. Through a triple resonance between the magnon mode, H-polarized, and V-polarized photon modes within the YIG optomagnonic cavity, we demonstrate an all-optical scheme to manipulate the optical polarization behaviors by adjusting an external driving laser, finding that the polarization states of the output light can be well mapped to the whole Poincar\'e sphere and a large polarization rotation of the output light with photon antibunching and superbunching can be achieved easily for a range of realistic parameters. We find the strong discrepancy in the polarization response between the exact numerical calculation using the full quantum master equation and the semiclassical approximation. In addition, we reveal the magnon-induced broken time-reversal symmetry, which connects the quantum cavity optomagnonics to the classical magneto-optical effect. Our obtained results have potential application in quantum polarization-state engineering, and also offer a further understanding for cavity optomagnonics at the quantum level.
We propose a feasible experimental model to investigate the generation and characterization of nonclassical states in a cavity optomagnonic system consisting of a ferromagnetic YIG sphere that simultaneously supports both the magnon mode and two whispering gallery modes of optical photons. The photons undergo the magnon-induced Brillouin light scattering, which is a well-established tool for the cavity-assisted manipulations of magnons as well as magnon spintronics. At first, we derive the desired interaction Hamiltonian under the influence of the anti-Stokes scattering process and then proceed to analyze the dynamical evolution of quantum statistics of photons and magnons as well as their intermodal entanglement. The results show that both photons and magnons generally acquire some nonclassical features, e.g., the strong antibunching and anti-correlation. Interestingly, the system may experience the perfect photon and magnon blockade phenomena, simultaneously. Besides, the nonclassical features may be protected against the unwanted environmental effects for a relatively long time, especially, in the weak driving field regime and when the system is initiated with a small number of particles. However, it should be noted that some fast quantum-classical transitions may occur in-between. Although the unwanted dissipative effects plague the nonclassical features, we show that this system can be adopted to prepare optomagnonic entangled states. The generation of entangled states depends on the initial state of the system and the interaction regime. The intermodal photon-magnon entanglement may be generated and pronounced, especially, if the system is initialized with low intensity even Schrödinger cat state in the strong coupling regime. The cavity-assisted manipulation of magnons is a unique and flexible mechanism that allows an interesting test bed for investigating the interdisciplinary contexts involving quantum optics and spintronics. Moreover, such a hybrid optomagnonic system may be used to design both on-demand single-photon and single-magnon sources and may find potential applications in quantum information processing.
By forming hybrid light-matter states, optical cavities offer a route for engineering material properties, however, unambiguously probing the effects of light-matter coupling remains difficult. Here, we show that the polarization-resolved statistics of photons transmitted through a cavity, measurable via g(2), provide one such diagnostic. By relating g(2) to matter correlation functions such as the Raman structure factor, we link photon bunching and antibunching to material properties. By applying this method to the stripy-to-antiferromagnetic transition in the Kitaev-Heisenberg spin model, we find that polarization-dependent patterns of bunching and antibunching encode the magnetic point-group symmetries of each phase and characterize the behavior at the phase boundary. Finally, we predict measuring g(2) for output photon pairs polarized orthogonal to the input field will isolate higher-order light-matter scattering processes that probe higher-order material correlations.
We present a proposal to test the Bell inequality in the emerging field of cavity optomagnonics, where a sphere of ferromagnetic crystal supports two optical whispering gallery modes and one magnon mode. The two optical modes are driven by two laser pulses, respectively. Entanglement between the magnon mode and one of the two optical modes will be generated by the first pulse, and the state of the magnon mode is subsequently mapped into another optical mode via the second pulse. Hence correlated photon-photon pairs are created out of the cavity. A Bell test can be implemented by using these pairs, which enables us to test the local hidden-variable models at macroscopic scales. Our results show that a significant violation of the Bell inequality can be obtained in the weak-coupling regime. The violation of the Bell inequality not only verifies the entanglement between magnons and photons, but also implies that cavity optomagnonics is a promising platform for quantum information processing tasks.
Coherently manipulating quadrature squeezing is highly desired for precision measurement applications, but remains challenging due to an inaccessible standard quantum limit in most micro- and nanostructures. Here, we propose an efficient scheme to generate quadrature squeezing in a cavity optomagnonical system. Taking the magnon–photon interaction induced by the Faraday effect into consideration, we report that a strong quadrature squeezing can be achieved in the effective resonant cavity modes that obey the mode-splitting theory of Bogoliubov transformation. Using experimentally achievable parameters, we illustrate that increasing the magnon–photon coupling strength or input field intensity contributes to improving both the output spectral intensity and the amount of squeezing of the spectra, where perfect squeezing is only located at the position of the single resonant cavity mode. Interestingly enough, the nearly perfect quadrature squeezing at the double frequencies of the effective resonant cavity modes can be achieved by adjusting the input field frequency and intensity.
Abstract Recently, the photon—magnon coherent interaction based on the collective spins excitation in ferromagnetic materials has been achieved experimentally. Under the prospect, the magnons are proposed to store and process quantum information. Meanwhile, cavity-optomagnonics which describes the interaction between photons and magnons has been developing rapidly as an interesting topic of the cavity quantum electrodynamics. Here in this short review, we mainly introduce the recent theoretical and experimental progress in the field of optomagnetic coupling and optical manipulation based on cavity-optomagnonics. According to the frequency range of the electromagnetic field, cavity optomagnonics can be divided into microwave cavity optomagnonics and optical cavity optomagnonics, due to the different dynamics of the photon—magnon interaction. As the interaction between the electromagnetic field and the magnetic materials is enhanced in the cavity-optomagnonic system, it provides great significance to explore the nonlinear characteristics and quantum properties for different magnetic systems. More importantly, the electromagnetic response of optomagnonics covers the frequency range from gigahertz to terahertz which provides a broad frequency platform for the multi-mode controlling in quantum systems.