Yttrium Iron Garnet Sphere Research Articles

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.

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.

Quantum Correlation Enhanced with Quantum Coherent Feedback Control in a Cavity‐magnon Hybrid System

AbstractA scheme is proposed to enhance quantum correlation, including entanglement and steering, for two magnon modes in a cavity‐magnon hybrid system through coherent quantum feedback. The hybrid system consists of a microwave cavity and two YIG spheres, which incorporates a nonlinear flux‐driven Josephson parametric amplifier in order for the generation of two photons within the cavity simultaneously. A quantum coherent feedback loop is used for the reduction of effective dissipation. By modulating feedback parameters, optimal bipartite and tripartite entanglement, as well as quantum steering are derived. Importantly, compared with the same setup without coherent feedback, the proposed scheme significantly improves quantum correlation. Furthermore, by optimizing the feedback reflectivity and the ratio of cavity‐magnon coupling strength, the enhancement of asymmetric steering can be controlled. Notably, incorporating the feedback loop effectively increase its robustness against thermal noise, thus the scheme offer better prospect for experimental development. This study paves the way for advancements in quantum information processing and quantum entanglement within cavity‐magnonics.

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.

[formula omitted]-symmetry induced bi-stability in non-Hermitian cavity magnomechanics

We study the steady-state non-Hermitian magnomechanical system driven by a transverse magnetic field directly interacting with YIG sphere yielding in magnons excitation, which later interacts with cavity microwave photons. To make the system non-Hermitian, we use a traveling field directly interacting with magnons generating gain to the system. We start by illustrating PT-configuration of the system containing two PT broken regions around exceptional point and PT protected region along the axis of exceptional point. We discover that the steady-state population of cavity photons and magnons show bistable behavior depending upon the PT configuration, which becomes more significant as the values of the magnon–photon coupling and traveling field strength increases. We illustrate that steady-state photon only shows bistable behavior when the system in lossy PT broken configuration, means strength of traveling field is less than the magnon–photon coupling. Otherwise, it will just contain a single stable state because of bistability suppression with gain in the system, which is unlike with any other investigation in this direction. Further, a larger magnon–photon coupling increases photon intensity and decreases magnon intensity, because of photon and magnon energy exchange, leading to enhanced photon bistablity and decreased magnon bistability. However, in case of increasing strength of traveling field, both photon as well as magnon bistability is appeared to be decreasing. We also study the steady-state effective potential of the system and illustrate the occurrence of bistability with nonlinear interactions between contour trajectories, which similarly depends on the PT broken configuration of the system.

Microwave quantum illumination: enhanced azimuth detection with cavity magnonics.

Most current microwave quantum illumination techniques rely on hybrid quantum systems to detect the presence of targets. However, real-world radar tasks are considerably more intricate than this simplistic model. Accurately determining physical attributes such as object speed, position, and azimuth is also essential. In this study, we explore azimuth detection using a quantum illumination approach based on a cavity-optomagnonics system and analyze the accuracy of azimuth detection in this framework. Our results indicate that this approach significantly outperforms classical microwave radar in azimuth detection within the parameters of current existing experiments. Additionally, we investigate the impact of Kerr nonlinearity of the YIG sphere on azimuth detection accuracy, revealing a clear improvement with the incorporation of Kerr nonlinearity.

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.

Maximum enhancement of entanglement in cavity magnomechanics

Quantum entanglement constitutes a fundamental resource for many advanced information processing tasks. That is why it is crucial to develop innovative methods for generating and improving its degree in quantum systems. In this regard, cavity magnomechanics incorporating yttrium-iron-garnet (YIG) spheres emerges as a promising platform for achieving macroscopic entanglement between cavity microwave photons, magnons, and phonons. Here, we propose a novel scheme that utilizes both coherent feedback and an optical parametric amplifier (OPA) to maximally enhance bipartite entanglement in a hybrid system composed of a YIG sphere placed inside a microwave cavity. By properly tuning the feedback and OPA parameters, we demonstrate an optimal enhancement of cavity-magnon and cavity-phonon entanglements, surpassing the maximum values achievable with either feedback or OPA alone. Notably, our scheme not only enhances entanglement but also increases its robustness against thermal noise, enabling its survival up to hundreds of milliKelvins. These findings pave the way for designing sophisticated cavity magnomechanics experiments aimed at observing macroscopic entanglement, with far-reaching implications in quantum information science.

Entanglement and quantum coherence of two YIG spheres in a hybrid Laguerre–Gaussian cavity optomechanics

We theoretically investigate continuous variable entanglement and macroscopic quantum coherence in the hybrid L–G rotational cavity optomechanical system containing two YIG spheres. In this system, a single L–G cavity mode and both magnon modes (which are due to the collective excitation of spins in two YIG spheres) are coupled through the magnetic dipole interaction whereas the L–G cavity mode can also exchange orbital angular momentum (OAM) with the rotating mirror (RM). We study in detail the effects of various physical parameters like cavity and both magnon detunings, environment temperature, optorotational and magnon coupling strengths on the bipartite entanglement and the macroscopic quantum coherence as well. We also explore parameter regimes to achieve maximum values for both of these quantum correlations. We also observed that the parameters regime for achieving maximum bipartite entanglement is completely different from macroscopic quantum coherence. So, our present study shall provide a method to control various nonclassical quantum correlations of macroscopic objects in the hybrid L–G rotational cavity optomechanical system and have potential applications in quantum sensing, quantum meteorology, and quantum information science.

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.

Nonreciprocity in cavity magnonics at millikelvin temperature

Incorporating cavity magnonics has opened up a new avenue in controlling non-reciprocity. This work examines a yttrium iron garnet sphere coupled to a planar microwave cavity at millikelvin temperature. Non-reciprocal device behavior results from the cooperation of coherent and dissipative coupling between the Kittel mode and a microwave cavity mode. The device’s bi-directional transmission was measured and compared to the theory derived previously in the room temperature experiment. Investigations are also conducted into key performance metrics such as isolation, bandwidth, and insertion loss. The findings point to the coexistence of coherent and dissipative interactions at cryogenic conditions, and one can leverage their cooperation to achieve directional isolation. This work foreshadows the application of a cavity magnonic isolator for on-chip readout and signal processing in superconducting circuitry.

Nonreciprocal magnon blockade via the Barnett effect.

We propose a scheme to achieve nonreciprocal magnon blockade via the Barnett effect in a magnon-based hybrid system. Due to the rotating yttrium iron garnet (YIG) sphere, the Barnett shift induced by the Barnett effect can be tuned from positive to negative via controlling magnetic field direction, leading to nonreciprocity. We show that a nonreciprocal unconventional magnon blockade (UMB) can emerge only from one magnetic field direction but not from the other side. Particularly, by further tuning system parameters, we simultaneously observe a nonreciprocal conventional magnon blockade (CMB) and a nonreciprocal UMB. This result achieves a switch between efficiency (UMB) and purity (CMB) of a single-magnon blockade. Interestingly, stronger UMB can be reached under stronger qubit-magnon coupling, even the strong coupling regime. Moreover, the nonreciprocity of the magnon blockade is sensitive to temperature. This work opens up a way for achieving quantum nonreciprocal magnetic devices and chiral magnon communications.

Quantum-interference-induced magnon blockade and antibunching in a hybrid quantum system

In this work, we study the phenomena of quantum-interference-assisted magnon blockade and magnon antibunching in a weakly interacting hybrid ferromagnet-superconductor system. The magnon excitations in two yttrium iron garnet spheres are indirectly coupled to a superconducting qubit through microwave cavity modes of two mutually perpendicular cavities. We find that when one of the magnon modes is driven by a weak microwave field, the destructive interference between more than two distinct transition pathways restricts the simultaneous excitation of two magnons. We analyze the magnon correlations in the driven magnon mode for the case of zero detunings as well as finite detunings of the magnon modes and the qubit. We show that the magnon antibunching can be tuned by changing the magnon-qubit coupling strength ratio and the driving detuning. Our work proposes a possible scheme that has a significant role in the construction of single magnon generating devices.

Parametrically amplified nonreciprocal magnon laser in a hybrid cavity optomagnonical system.

We propose a scheme to achieve a tunable nonreciprocal magnon laser with parametric amplification in a hybrid cavity optomagnonical system, which consists a yttrium iron garnet (YIG) sphere and a spinning resonator. We demonstrate the control of magnon laser can be enhanced via parametric amplification, which make easier and more convenient to control the magnon laser. Moreover, we analyze and evaluate the effects of pump light input direction and amplification amplitude on the magnon gain and laser threshold power. The results indicate that we can obtian a higher magnon gain and a broader range of threshold power of the magnon laser. In our scheme both the nonreciprocity and magnon gain of the magnon laser can be increased significantly. Our proposal provides a way to obtain a novel nonreciprocal magnon laser and offers new possibilities for both nonreciprocal optics and spin-electronics applications.