Garnet Sphere Research Articles

Transmitting squeezed states in a cascaded cavity-magnonic system

The squeezed state has wide applications in quantum information and metrology. This work demonstrates the long-distance transmission of a squeezed state, where we utilize a cavity-magnonic system composed of a cascaded cavity and a yttrium iron garnet sphere. The squeezed source, originating from a flux-driven Josephson parametric amplifier, is mediated through six cavity modes and ultimately transmitted to magnon mode. With appropriate detuning matching, state transmission can be blocked at any mode, and the difference in squeezing phase between adjacent modes is π. Squeezed magnons exhibit high robustness against environmental temperature and magnetic damping. Our work provides prior guidance for multi-mode transmission of quantum states in continuous variable systems.

Nonreciprocal Strong Mechanical Squeezing Based on the Kerr Effect in Cavity‐Magnon Optomechanical System

AbstractIn this study, a scheme is proposed to generate nonreciprocal strong mechanical squeezing in a cavity‐magnon optomechanical system based on the Kerr nonlinearity of the yttrium‐iron garnet (YIG) sphere. It is found that the magnon squeezing can be directly produced by the Kerr effect and it can induce strong mechanical squeezing through the squeezing transfer achieved by the cavity‐magnon interaction and the optomechanical interaction. The results further show that the mechanical mode coupled to the cavity can achieve squeezing effect in the selected magnetic field direction, but not in the opposite one. Moreover, by properly adjusting the magnon effective detuning and the Kerr effect strength, the degree of squeezing of the mechanical mode can even beyond the 3‐dB limit, and the optimal conditions for generating stronger squeezing are obtained. This work has important applications in the nonreciprocal quantum devices, quantum information processing, and quantum precision measurement.

Controllable antibunching of two-magnon bundle in a hybrid ferromagnet-superconductor system.

We propose an alternative scheme for implementing the antibunching effects of two-magnon bundle in a hybrid ferromagnet-superconductor system, where a magnon mode from the yttrium iron garnet (YIG) sphere interacts with a three-level superconducting qubit via photon virtual excitation in the microwave cavity. With the help of the qubit driving from the ground state to the excited state, the cascaded emission of magnon occurs and then the two-magnon bundle is formed. By analyzing the ordinary and generalized second-order correlation functions, it is found that the antibunched two-magnon bundle could be achieved via properly choosing the system parameters, which is originated from the anharmonicity of dressed energy levels induced by magnon-qubit couplings. The distinct feature is that high-proportion n-magnon emission could be obtained via relaxing the restriction on the strong qubit driving and magnon-qubit coupling, which may provide a feasible method to realize the high-quality multimagnon source for quantum metrology and quantum information processing.

Tunable bistability, optomechanical and magnomechanically induced transparency in opto-magnomechanical system

We investigate theoretically the optical properties of a hybrid optomechanical system embedded with a yttrium iron garnet (YIG) sphere. It is considered that YIG interacts with a single mode of the microcavity through magnetic dipole coupling. To enhance the magnomechanical coupling, the magnon mode is directly driven by a microwave field. The microcavity is driven by the control and probe field. The study of steady-state dynamics of the system shows bistable behavior. Furthermore, optomechanically induced transparency under the influence of a strong control field in the system is explored. In addition, magnomechanically induced transparency (MMIT) due to the presence of nonlinear magnon–phonon interaction is studied. Fano like shape is observed in MMIT. The impact of different system parameters is studied. Our results will provide a theoretical approach to understand opto-magnomechanical systems. These results may be useful in all optical switching devices and optical transistors.

Kerr nonlinearity-induced nonreciprocal Einstein–Podolsky–Rosen steering in a cavity magnonic system

Abstract We propose to utilize magnon Kerr nonlinearity to generate and control microwave–microwave Einstein–Podolsky–Rosen (EPR) steering in a cavity magnonic system consisting of two microwave cavities and an yttrium iron garnet (YIG) sphere, where the magnon mode in the YIG sphere is driven by an electromagnetic field. The results show that Kerr nonlinearity of the magnon could not only sensibly induce enhanced entanglement of two microwave fields but also produce asymmetric EPR steering with different ratios of two damping rates and coupling constants. Moreover, it is found that the nonreciprocity of the steady-state EPR steering is obtainable by controlling the sign of the magnon Kerr parameter, which could be tuned from positive to negative by changing the direction of the static magnetic field. The demonstrated nonreciprocal EPR steering is of fundamental interest for the manipulation of quantum states, and may provide potential applications in quantum information tasks.

Dissipation-induced nonreciprocal magnon entanglement and one-way steering in waveguide electromagnonics.

We propose a scheme to generate nonreciprocal entanglement and one-way steering between two distant ferrimagnetic microspheres in waveguide electromagnonics, where the magnon modes of two yttrium iron garnet (YIG) spheres are simultaneously coupled to each other through coherent and dissipative interactions. By matching the coherent interaction with its corresponding dissipative counterpart, unidirectional coupling between two magnon modes can be realized, and then in the presence of significant Kerr nonlinearities, we can obtain strong entanglement and one-way steering. Depending on the direction of the microwave propagation, the long-distance entanglement and steering can be generated nonreciprocally. Our work presents a novel, to the best of our knowledge, approach for generating nonreciprocal quantum correlations, which may find potential applications in chiral quantum networking.

Generation and enhancement of sum sideband in a magnon Kerr nonlinearity assisted optomechanical system

Abstract A theoretical scheme to enhance the sum sideband generation (SSG) via magnon Kerr nonlinearity assisted optomechanical system is proposed. In this scheme, the yttrium iron garnet sphere is placed within the cavity system and the frequency components are generated at the sum sideband through optomechanical nonlinear interaction and cavity-magnon linear coupling interaction. The results show that the efficiency of SSG can be enhanced by several orders of magnitude, and the gain in SSG efficiency also varies. The dependence of SSG on the system parameters, including the power of the control field, the frequency detuning of the probe fields and the coupling strengths between the optomechanical coupling and the cavity-magnon coupling is analyzed in detail. The change of SSG by varying the optomechanical coupling strength and cavity-magnon coupling strength is also investigated, and it is found that new matching conditions are generated. The enhanced SSG method may have potential application prospects in realizing the measurement of high-precision weak forces, quantum information processing and quantum-sensitive sensing.

Unconventional magnon blockade in a dissipative photon–magnon coupling system

We investigate unconventional magnon blockade (UMB) in a dissipative photon–magnon coupling cavity, where the coherent and dissipative coupling between photon and magnon can be adjusted by the position of the yttrium iron garnet sphere in the cavity. An approximate analytical solution for the statistical property of magnon is provided, which is in good agreement with the results obtained by numerically solving the Lindblad master equation. Our results indicate that UMB can be achieved in the case of dissipative photon–magnon coupling, but not in the case of coherent photon–magnon coupling. Secondly, by adjusting the amplitude of the external laser field, dynamic control of UMB can be achieved. Finally, by solving the Lindblad master equation containing the occupation number of thermal magnon and photon, the statistical properties of magnons will transition from nonclassical to classical. It is shown that the above phenomena originate from the interference between different quantum paths. Our research may provide theoretical possibilities for quantum manipulation schemes at the single-magnon level and open up a new avenue for designing single-magnon sources in a dissipative photon–magnon coupling system.

Three-cavity system with multiple magnomechanically induced transparency

This paper presents the characteristics of a weak probe field in a three-connected cavity system. In this system, a microwave cavity contains a yittrium iron garnet sphere that is driven by a strong pump and a weak probe optical fields, and the magnon is driven by a weak microwave source. The other two cavities are empty and are coupled to the first cavity with specific coupling strengths. This setup leads to the observation of multiple magnomechanically induced transparency phenomena by varying quantum parameters g ma, g mb, and the coupling strengths between cavities J 1 and J 2. The study of these phenomena in the three coupled cavities can potentially contribute to advancements in quantum transduction and future technologies.

Optical frequency combs and chaos in a hybrid atom–cavity optomagnonical system via the synergy of double-probe fields

We theoretically investigate the modulation of optical frequency combs and chaos by the synergy of double-probe fields in the hybrid atom–cavity optomagnonical system consisting of a yttrium iron garnet sphere, a two-level atom, and a tapered fiber. Our results show that in the case of a single-probe field, the atom-optical mode coupling strength and amplitude strength of the probe field can effectively modify the tooth spacing (from one to one-half tooth spacing) of the optical frequency combs, as well as the entry or withdrawal of chaos. In a chaotic region, the relative phases between the control and probe fields can also be adjusted to withdraw chaotic motion. Moreover, we demonstrate the generation of hybridized fraction-order frequency combs via the synergy of double-probe fields, which is caused by the sum and difference frequency effects of sidebands. Interestingly, it is found that through the synergy of the double-probe fields, the system can enter a chaotic state under lower applied field intensity, which is modulated by the amplitude strengths and relative phases of the dual probe fields. In addition to providing insight into the characteristics of optical frequency combs and chaos in the hybrid atom–cavity optomagnonical system, our research may offer a new perspective for the development of precision measurements and secret information processing.

Generation of second-order sidebands and slow–fast light in cavity magnomechanics with a parametric amplifier

In this work, we theoretically investigate the optical second-order sideband (OSS) efficiency and group delay of an output probe field in a two-coupled cavity magnomechanics (CMM) system. The setup comprises a gain (active) cavity and a passive (loss) cavity, which simultaneously includes an optical parametric amplifier (OPA) and a yttrium iron garnet sphere to facilitate magnon–photon coupling. Employing experimentally attainable parameters, we show that the presence of an OPA can significantly enhance the optical transmission rate and OSS efficiency. We show that photon–magnon strong coupling can enhance OSS efficiency substantially when compared to weak photon–magnon coupling. Our results, in particular, show that the OSS’s efficiency may be significantly improved for active–passive-coupled cavities as compared to the passive–passive cavities system. Furthermore, we demonstrate that modifying the system configurations may change the group delay, affecting the transition from rapid to slow light propagation, and vice versa. Our results provide a novel and easy approach to designing CMM devices for altering light propagation, with possible applications including optical switching, information storage, and accurate measurement of weak signals.

Entropy production rate and correlations in a cavity magnomechanical system

We present the irreversibility generated by a stationary cavity magnomechanical system composed of a yttrium iron garnet (YIG) sphere with a diameter of a few hundred micrometers inside a microwave cavity. In this system, the magnons, i.e., collective spin excitations in the sphere, are coupled to the cavity photon mode via magnetic dipole interaction and to the phonon mode via magnetostrictive force (optomechanical-like). We employ the quantum phase-space formulation of the entropy change to evaluate the steady-state entropy production rate and associated quantum correlation in the system. We find that the behavior of the entropy flow between the cavity photon mode and the phonon mode is determined by the magnon-photon coupling and the cavity photon dissipation rate. Interestingly, the entropy production rate can increase/decrease depending on the strength of the magnon-photon coupling and the detuning parameters. We further show that the amount of correlations between the magnon and phonon modes is linked to the irreversibility generated in the system for small magnon-photon coupling. Our results demonstrate the possibility of exploring irreversibility in driven magnon-based hybrid quantum systems and open a promising route for quantum thermal applications. Published by the American Physical Society 2024

Detection of entanglement by harnessing extracted work in magnomechanics

The connections between thermodynamics and quantum information processing are of paramount importance. Here, we address a bipartite entanglement via extracted work in a cavity magnomechanical system contained inside an yttrium iron garnet (YIG) sphere. The photons and magnons interact through an interaction between magnetic dipoles. A magnetostrictive interaction, analogous to radiation pressure, couple’s phonons and magnons. The extracted work was obtained through a device similar to the Szilárd engine. This engine operates by manipulating the photon–magnon as a bipartite quantum state. We employ logarithmic negativity to measure the amount of entanglement between photon and magnon modes in steady and dynamical states. We explore the extracted work, separable work, and maximum work for squeezed thermal states. We investigate the amount of work extracted from a bipartite quantum state, which can potentially determine the degree of entanglement present in that state. Numerical studies show that entanglement, as detected by the extracted work and quantified by logarithmic negativity, are in good agreement. We show the reduction of extracted work by a second measurement compared to a single measurement. Also, the efficiency of the Szilárd engine in steady and dynamical states is investigated. We hope this work is of paramount importance in quantum information processing.

Magnon‐Squeezing‐Enhanced Phonon Lasering in Cavity Magnomechanics

AbstractPhonon lasers have long been a subject of interest and possess broad application prospects. Much effort is devoted to lay the foundation of realizing phonon lasers using cavity magnomechanical systems, but up to now no related work is carried out to explore the quantum‐squeezing‐engineered phonon laser action in cavity magnomechanics. Here, the phonon laser action is investigated in a three‐mode cavity magnomechanical system built based on a microwave resonator‐yttrium iron garnet sphere composite device, focusing on the effect induced by the magnon‐mode squeezing. It is found that the magnon squeezing can improve the effective magnon–photon and magnon–phonon coupling rates. It is demonstrated that the phonon laser action can be engineered and enhanced by changing the squeezing strength. This scheme provides a new mechanism to improve the effective magnon–photon and magnon–phonon couplings for various applications, and demonstrates the feasibility of realizing high‐gain and low‐threshold phonon lasers with cavity magnomechanical platforms.

Nonreciprocal Unconventional Photon Blockade with Kerr Magnons

AbstractNonreciprocal devices, allowing to manipulate one‐way signals, are crucial to quantum information processing and quantum networks. Here a nonlinear cavity‐magnon system is proposed, consisting of a microwave cavity coupled to one or two yttrium–iron–garnet (YIG) spheres supporting magnons with Kerr nonlinearity, to investigate nonreciprocal unconventional photon blockade. The nonreciprocity originates from the direction‐dependent Kerr effect, distinctly different from previous proposals with spinning cavities and dissipative couplings. For a single sphere case, nonreciprocal unconventional photon blockade can be realized by manipulating the nonreciprocal destructive interference between two active paths, via varying the Kerr coefficient from positive to negative, or vice versa. By optimizing the system parameters, the perfect and well‐tuned nonreciprocal unconventional photon blockade can be predicted. For the case of two spheres with opposite Kerr effects, only reciprocal unconventional photon blockade can be observed when two cavity‐magnon coupling strengths Kerr strengths are symmetric. However, when coupling strengths or Kerr strengths become asymmetric, nonreciprocal unconventional photon blockade appears. This implies that two‐sphere nonlinear cavity‐magnon systems can be used to switch the transition between reciprocal and nonreciprocal unconventional photon blockades. This study offers a potential platform for investigating the nonreciprocal photon blockade effect in nonlinear cavity magnonics.

Magnon-photon coupling in an opto-electro-magnonic oscillator

The opto-electronic oscillators (OEOs) hosting self-sustained oscillations by a time-delayed mechanism are of particular interest in long-haul signal transmission and processing. On the other hand, owing to their unique tunability and compatibility, magnons—as elementary excitations of spin waves—are advantageous carriers for coherent signal transduction across different platforms. In this work, we integrated an opto-electronic oscillator with a magnonic oscillator consisting of a microwave waveguide and a yttrium iron garnet sphere. We find that, in the presence of the magnetic sphere, the oscillator power spectrum exhibits sidebands flanking the fundamental OEO modes. The measured waveguide transmission reveals anti-crossing gaps, a hallmark of the coupling between the opto-electronic oscillator modes and the Walker modes of the sphere. Experimental results are well reproduced by a coupled-mode theory that accounts for nonlinear magnetostrictive interactions mediated by the magnetic sphere. Leveraging the advanced fiber-optic technologies in opto-electronics, this work lays out a new, hybrid platform for investigating long-distance coupling and nonlinearity in coherent magnonic phenomena.

Hybrid magnon-photon bundle emission from a ferromagnetic-superconducting system

We show that the hybrid magnon-photon bundle emission is possible to generate by employing a three-level Δ-type superconducting artificial atom. The single atom is dispersively coupled with two microwave cavities, one of which simultaneously couples to a yttrium iron garnet (YIG) sphere via the magnetic dipole interaction. Based on the virtual photon exchange, the indirect magnon-atom interaction is established with flexibly tunable coupling strength, thus leading to the consecutive emission of hybrid magnon-photon pairs. The super-Rabi oscillation and Purcell effect make such a hybrid bundle possible in the present three-level system, which is difficult to achieve in the two-level system. The present scheme may find potential applications in quantum information processing and quantum sensing technology. Published by the American Physical Society 2024

Nonreciprocal magnon blockade based on nonlinear effects.

We present an alternative scheme to achieve nonreciprocal unconventional magnon blockade (NUMB) in a hybrid system formed by two microwave cavities and one yttrium iron garnet (YIG) sphere, where the pump and signal cavities interact nonlinearly with each other and the signal cavity is coupled to the YIG sphere. It is found that the nonlinear coupling occurs between the pump cavity and magnon modes due to the dispersive interactions among three bosonic modes. Meanwhile, the Kerr nonlinearity is present in the pump cavity. Based on these nonlinear effects, a nonreciprocal magnon blockade could be achieved with the help of the weak parametric driving of the pump cavity. The present work provides an alternative method to prepare single magnon resource, which may be helpful for quantum information processing.

Controllable switching of the magnonic excitation based on the magnetostrictive effect

The magnetostrictive effect in a yttrium iron garnet sphere induces a coherent interaction between magnetization and elastic strain. The dispersive-type coupling between the ferromagnetic magnon mode and the phonon mode is treated analytically, and the features of the magnonic excitation are discussed. We show that the resonant magnonic excitation of a signal driving field can be well controlled by another strong field via the interference of the excitation pathways, which results in convenient magnonic control and enables a magnonic switch with excellent functionality. The parameter optimization of the system has been performed to expand the operating bandwidth, and the influence of thermal noises to the magnonic switch has been discussed. Our analysis may provide a viable tool for controlling the magnonic excitation in magnetic materials and find applications in designing magnon-based devices.

Thermal noise energy regulation in a double-cavity magnomechanical system

We investigate the thermal transport characteristics in a double-cavity magnomechanical system with a yttrium iron garnet sphere. We explore mainly the performance parameter of the thermo-phonon flux flowing from the thermal bath of a mechanical motion into the magnomechanical system and study its dependence on the cavity field detuning and decay, the magnon-photon and magnon-phonon coupling strengths, and the Kerr nonlinear coefficient of magnon. We find that the direction and magnitude of the steady-state thermophonon flux in the magnomechanical system can be controlled flexibly by modulating these system parameters. In particular, the interference effect of quantum transitions in the multi-mode magnomechanical system results a multiple dip structure in the heat flow pattern. The results obtained her e help demonstrate the thermal noise energy harvesting and rectification by the cavity magnomechanical setup.