Cavity Magnomechanical System Research Articles

On-Chip Coherent Transduction between Magnons and Acoustic Phonons in Cavity Magnomechanics

Magnons, namely spin waves, are collective spin excitations in ferromagnets, and their control through coupling with other excitations is a key technology for future hybrid spintronic devices. Although strong coupling has been demonstrated with microwave photonic structures, an alternative approach permitting high density integration and minimized electromagnetic crosstalk is required. Here we report a planar cavity magnomechanical system, where the cavity of surface acoustic waves enhances the spatial and spectral power density to thus implement magnon-phonon coupling at room temperature. Excitation of spin-wave resonance involves significant acoustic power absorption, whereas the collective spin motion reversely exerts a back-action force on the cavity dynamics. The cavity frequency and quality-factor are significantly modified by the back-action effect, and the resultant cooperativity exceeds unity, suggesting coherent interaction between magnons and phonons. The demonstration of a chip-scale magnomechanical system paves the way to the development of novel spin-acoustic technologies for classical and quantum applications.

Manipulation of One‐Way Gaussian Steering via Quantum Correlated Microwave Fields

AbstractManipulation of one‐way Gaussian steering in macroscopic systems is outstandingly challenging in modern physics. In this paper, a cavity magnomechanical system is used which is composed of two spatially separate microwave cavities and two massive yttrium iron garnet (YIG) spheres in order for one‐way Gaussian steering. The two cavities are pumped by a two‐mode squeezed light, while both two YIG spheres are individually driven by a classical field at a red sideband with respect to the magnon mode. By creating different excitations for the two phonon modes, the systemic symmetry is broken and one‐way Gaussian steering with strong entanglement between two phonon modes induced by the deformation of YIG spheres is achieved. This finding may provide a novel method to manipulate asymmetric quantum steering between two long‐distance macroscopic objects which is of great importance for quantum information processing.

Perfect transfer of enhanced entanglement and asymmetric steering in a cavity-magnomechanical system

We propose a hybrid cavity magnomechanical system to realize and transfer the bipartite entanglements and Einstein-Podolsky-Rosen (EPR) steerings between magnons, photons, and phonons in the regime of stability of the system. As a parity-time-symmetric-like structure exhibiting the natural magnetostrictive magnon-phonon interaction, our passive-active cavity system can be explored to enhance the robust distant quantum entanglement and generate the relatively obvious asymmetric (even directional) EPR steering that is useful for the task with the highly asymmetric trusts of the bidirectional local measurements between two entangled states. It is of great interest that, based on such a tunable magnomechanical system, the perfect transfer between near and distant entanglements and steerings of different mode pairs is realized by adjusting the coupling parameters; in particular, we propose a perfect transfer scheme of steerings. These transferring processes suggest indeed an alternative method for quantum information storage and manipulation. In addition, the entanglements and steerings can also be exchanged between different mode pairs by adjusting the detunings between different modes. This work may provide a potential platform for distant and asymmetric quantum modulation.

Generation and transfer of squeezed states in a cavity magnomechanical system by two-tone microwave fields.

We propose a scheme to generate squeezed states of magnon and phonon modes and verify squeezing transfer between different modes of distinct frequencies in a cavity magnomechanical system which is composed of a microwave cavity and a yttrium iron garnet sphere. We present that by activating the magnetostrictive force in the ferrimagnet, realized by driving the magnon mode with red-detuned and blue-detuned microwave fields, the driven magnon mode can be prepared in a squeezed state. Moreover, the squeezing can be transferred to the cavity mode via the cavity-magnon beamsplitter interaction with strong magnomechanical coupling. We show that under the weak coupling regime, large mechanical squeezing of phonon mode can be achieved, which verifies that our scheme can find the existence of quantum effects at macroscopic scales. Furthermore, distinct parameter regimes for obtaining large squeezing of the magnons and phonons are given, which is the principal feature of our scheme. The considered scheme can be extended to hybrid optical systems, and can facilitate the advancement for realization of strong mechanical squeezing in cavity magnomechanical systems.

Enhanced entanglement and steering in [formula omitted] -symmetric cavity magnomechanics

We study creation of entanglement and quantum steering in a parity-time- (PT-) symmetric cavity magnomechanical system. There are photon–magnon coupling and phonon–magnon coupling in this system. By introducing a gain cavity mode, a PT-symmetric Hamiltonian of the system is obtained. We find that bipartite entanglement and magnon→phonon steering in PT-symmetry system (gain–loss system) are significantly enhanced versus the case in the conventional cavity magnomechanical system (loss–loss system). Moreover, the magnon→phonon one-way-like quantum steering can be realized in unbroken-PT-symmetry regime. The boundary of stability is demonstrated and it shows that the gain–loss system becomes more stable with respect to the conventional loss–loss system under the parameters we consider. This work opens up a route to explore the characteristics of quantum entanglement and steering in magnomechanical systems, which might have potential applications in quantum state engineering and quantum information.

Phase control of the transmission in cavity magnomechanical system with magnon driving

We investigate the coherent control of the transmission spectrum in a cavity magnetomechanical system consisting of microwave photon, magnon, and phonon modes, where the microwave cavity is driven by a strong pump field and a weak probe field, and the magnon is driven by a weak microwave source. Different from a single transparency window in the absence of the phonon–magnon interaction, two transparency windows and three absorption dips can be observed in the presence of the phonon–magnon interaction, which originates from the joint interaction of phonon–magnon and photon–magnon. In addition, two absorption dips located at both sides of the central absorption dip can be modulated asymmetrically into amplification and absorption by varying the magnetic field amplitude of the magnon driving field. Interestingly enough, the relative phase of applied fields could have profound effects on both the transmission spectrum and the group delay of the output field by choosing the appropriate magnetic field amplitude of the magnon driving field. The transmission group delay can be switched between positive to negative and vice versa by adjusting the relative phase between the applied fields. The present results illustrate the potential to utilize the relative phase for controlling the microwave signal in the cavity magnomechanical system, as well as guidance in the design of information transduction and quantum sensing.

Ground state cooling of magnomechanical resonator in $${\cal P}{\cal T}$$-symmetric cavity magnomechanical system at room temperature

We propose to realize the ground state cooling of magnomechanical resonator in a parity-time ( $${\cal P}{\cal T}$$ )-symmetric cavity magnomechanical system composed of a loss ferromagnetic sphere and a gain microwave cavity. In the scheme, the magnomechanical resonator can be cooled close to its ground state via the magnomechanical interaction, and it is found that the cooling effect in $${\cal P}{\cal T}$$ -symmetric system is much higher than that in non- $${\cal P}{\cal T}$$ -symmetric system. Resorting to the magnetic force noise spectrum, we investigate the final mean phonon number with experimentally feasible parameters and find surprisingly that the ground state cooling of magnomechanical resonator can be directly achieved at room temperature. Furthermore, we also illustrate that the ground state cooling can be flexibly controlled via the external magnetic field.

Tunable multiwindow magnomechanically induced transparency, Fano resonances, and slow-to-fast light conversion

We investigate the absorption and transmission properties of a weak probe field under the influence of a strong control field in a cavity magnomechanical system. The system consists of two ferromagnetic-material yttrium iron garnet (YIG) spheres coupled to a single cavity mode. In addition to two magnon-induced transparencies (MITs) that arise due to magnon-photon interactions, we observe a magnomechanically induced transparency (MMIT) due to the presence of nonlinear magnon-phonon interaction. We discuss the emergence of Fano resonances and explain the splitting of a single Fano profile to double and triple Fano profiles due to additional couplings in the proposed system. Moreover, by considering a two-YIG system, the group delay of the probe field can be enhanced by one order of magnitude as compared with a single-YIG magnomechanical system. Furthermore, we show that the group delay depends on the tunability of the coupling strength of the first YIG with respect to the coupling frequency of of the second YIG, and vice versa. This helps to achieve larger group delays for weak magnon-photon coupling strengths.

Magnon Blockade in a PT‐Symmetric‐Like Cavity Magnomechanical System

AbstractThe magnon blockade effect in a parity‐time () symmetric‐like three‐mode cavity magnomechanical system involving the magnon–photon and magnon–phonon interactions is investigated. In the broken and unbroken ‐symmetric regions, the second‐order correlation function is calculated analytically and numerically, respectively, and the optimal value of detuning is further determined. By adjusting different system parameters, the different blockade mechanisms are studied and it is found that the perfect magnon blockade effect can be observed under the weak parameter mechanism. This work paves a way to achieve the magnon blockade in experiment.

Ground-state cooling of a magnomechanical resonator induced by magnetic damping

Quantum manipulation of mechanical resonators has been widely applied in fundamental physics and quantum information processing. Among them, cooling a mechanical system to its quantum ground state is regarded as a key step. In this work, we propose a scheme that can realize ground-state cooling of the resonator in a cavity magnomechanical system. The system consists of a microwave cavity and a small ferromagnetic sphere, in which phonon–magnon coupling and cavity photon–magnon coupling can be achieved via magnetostrictive interaction and magnetic dipole interaction, respectively. Within experimentally feasible parameters, we demonstrate that the extra magnetic damping can be utilized to achieve ground-state cooling of the magnomechanical resonator via an effective dark-mode interaction. The magnomechanical cooling mainly comes from the magnon–phonon interaction terms. We further illustrate that optimal cooling can be obtained by adjusting the external magnetic field.

Generation of higher-order sidebands based on the magnetostrictive interaction in a hybrid cavity electro–opto–magnomechanical system

Magnetostrictive interaction, as a nonlinear effect, provides a great opportunity to establish a tunable cavity magnomechanical system and may bring many interesting physical phenomena and potential applications. Here, we theoretically investigate the generation and control of higher-order sideband phenomena in a hybrid cavity electro–opto–magnomechanical system, in which the geometrical deformation of yttrium iron garnet can be treated as an excellent mechanical resonator. We show that the amplitude of the sideband can be considerably enhanced in the case of blue detuning of the microwave cavity field, and we also find an interesting pump-field-detuning-controlled optical switch effect. Furthermore, numerical calculations of the system’s dynamic equations show excellent agreement with our analytical results. Our results will contribute to the understanding of nonlinear coherent phenomena and have the potential to greatly advance the fields of cavity electro–opto–magnomechanical systems and nonlinear optics.

Genuine photon-magnon-phonon Einstein-Podolsky-Rosen steerable nonlocality in a continuously-monitored cavity magnomechanical system

The authors consider the utilization of time-continuous quantum measurement to achieve hybrid photon-magnon-phonon Einstein-Podolsky-Rosen nonlocality in a cavity magnomechanical interface. This scheme demonstrates the measurement-based control of quantum phenomena in macroscopic systems

Phonon laser in a cavity magnomechanical system

Using phonons to simulate an optical two-level laser action has been the focus of research. We theoretically study phonon laser in a cavity magnomechanical system, which consist of a microwave cavity, a sphere of magnetic material and a uniform external bias magnetic field. This system can realize the phonon-magnon coupling and the cavity photon-magnon coupling via magnetostrictive interaction and magnetic dipole interaction respectively, the magnons are driven directly by a strong microwave field simultaneously. Frist, the intensity of driving magnetic field which can reach the threshold condition of phonon laser is given. Then, we demonstrate that the adjustable external magnetic field can be used as a good control method to the phonon laser. Compared with phonon laser in optomechanical systems, our scheme brings a new degree of freedom of manipulation. Finally, with the experimentally feasible parameters, threshold power in our scheme is close to the case of optomechanical systems. Our study may inspire the field of magnetically controlled phonon lasers.

Entangling two magnon modes via magnetostrictive interaction

We present a scheme to entangle two magnon modes in a cavity magnomechanical system. The two magnon modes are embodied by collective motions of a large number of spins in two macroscopic ferrimagnets, and couple to a single microwave cavity mode via magnetic dipole interaction. We show that by activating the nonlinear magnetostrictive interaction in one ferrimagnet, realized by driving the magnon mode with a strong red-detuned microwave field, the two magnon modes can be prepared in an entangled state. The entanglement is achieved by exploiting the nonlinear magnon-phonon coupling and the linear magnon-cavity coupling, and is in the steady state and robust against temperature. The entangled magnon modes in two massive ferrimagnets represent genuinely macroscopic quantum states, and may find applications in the study of macroscopic quantum mechanics and quantum information processing based on magnonics.

Magnon Chaos in $PT$-Symmetric Cavity Magnomechanics

Here, we research a novel cavity magnomechanical system, where the magnon mode with Kerr nonlinearity driven by a microwave field couples to a phonon mode with a magneostrictive nonlinear interaction (radiation pressure-like). Based on these nonlinear properties, we numerically demonstrate magnon chaos in the PT-symmetry and PT-symmetry broken regimes in the system. In the PT-symmetry broken phase, the magnon-chaos driving threshold is lowered to a rather low levels benefited from the enhancement of the system nonlinearities. Moreover, by expenediently manipulating the phase transition between PT-symmetry and PT-symmetry broken regimes, we can switch the system between into and out of chaotic regimes. Our work may broaden the cavity magnomehcnaics and provide a promising application for magnetic chaos-related security communications.

Enhanced sideband responses in a PT -symmetric-like cavity magnomechanical system

Based on the cavity magnomechanical system, which consists of a microwave cavity and a small ferromagnetic sphere, we propose a scheme to construct a parity-time- $\left(\mathcal{PT}\ensuremath{-}\right)$ symmetric-like system formed by the active magnon mode and passive cavity mode. The effective gain of the magnon mode is achieved by resonantly driving the yttrium iron garnet (YIG) sphere and can be modulated by the power of the driving field. We show the $\mathcal{PT}$-symmetric phase transition following the variation of magnon-photon coupling strength in microwave regime. We find that the transmission amplitudes and time delays on the first- and second-order sidebands in the $\mathcal{PT}$-symmetric-like system can be enhanced for three to four orders, compared to the magnomechanical system, once the magnon-photon coupling strength is tuned to the critical point in the broken-$\mathcal{PT}$-symmetry regime. Particularly, we also show the switching between different transmission spectra (amplification or magnomechanically induced absorption) and time delay (positive or negative) on the first-order Stokes sideband can be achieved by modulating the power of the control field, cavity-waveguide coupling parameter, and magnon-photon coupling strength. Our study shows that the cavity magnomechanical system is a promising platform for exploring $\mathcal{PT}$-symmetric-like paradigms in microwave field, and a good candidate for the microwave control on both the first- and high-order sidebands simultaneously. Our study may inspire further applications in frequency combs and low-power magnomechanical amplifier.

Squeezed states of magnons and phonons in cavity magnomechanics

We show how to create quantum squeezed states of magnons and phonons in a cavity magnomechanical system. The magnons are embodied by a collective motion of a large number of spins in a macroscopic ferrimagnet, and couple to cavity microwave photons and phonons (vibrational modes of the ferrimagnet) via the magnetic dipole interaction and magnetostrictive interaction, respectively. The cavity is driven by a weak squeezed vacuum field generated by a flux-driven Josephson parametric amplifier, which is essential to get squeezed states of the magnons and phonons. We show that the magnons can be prepared in a squeezed state via the cavity-magnon beamsplitter interaction, and by further driving the magnon mode with a strong red-detuned microwave field, the phonons are squeezed. We show optimal parameter regimes for obtaining large squeezing of the magnons and phonons, which are robust against temperature and could be realized with experimentally reachable parameters.

Magnon-Photon-Phonon Entanglement in Cavity Magnomechanics.

We show how to generate tripartite entanglement in a cavity magnomechanical system which consists of magnons, cavity microwave photons, and phonons. The magnons are embodied by a collective motion of a large number of spins in a macroscopic ferrimagnet, and are driven directly by an electromagnetic field. The cavity photons and magnons are coupled via magnetic dipole interaction, and the magnons and phonons are coupled via magnetostrictive (radiation pressurelike) interaction. We show optimal parameter regimes for achieving the tripartite entanglement where magnons, cavity photons, and phonons are entangled with each other, and we further prove that the steady state of the system is a genuinely tripartite entangled state. The entanglement is robust against temperature. Our results indicate that cavity magnomechanical systems could provide a promising platform for the study of macroscopic quantum phenomena.