Bosonic two-mode squeezed states are paradigmatic entangled states in continuous variable systems, which have broad applications in quantum information processing. In this work, we propose a photon-phonon squeezing protocol assisted by a Kerr magnon within a hybrid cavity magnomechanical system. We construct an effective Hamiltonian that accounts for photon-phonon squeezing through strong photon-magnon interaction and modulation over the driving on the photon mode. The effective Hamiltonian can be confirmed by the diagonalization of the system's Liouvillian superoperator. With the effective Hamiltonian and quantum Langevin equation, we provide a rigorous theoretical solution for the dynamical process of squeezing generation. Our finding indicates that the asymptotic stationary squeezing can be obtained by optimizing the squeezing quadrature operator, even when the covariance matrix of the system still varies with time. This squeezing level can exceed the maximum value under stable conditions. Moreover, our analysis reveals that a proper Kerr nonlinearity of the magnon can further promote the squeezing generation. Our work provides an extendable framework for generating squeezed states of two Gaussian modes with indirect coupling.
Bosonic two-mode squeezed states are paradigmatic entangled states in continuous variable systems, which have broad applications in quantum information processing. In this work, we propose a photon-phonon squeezing protocol assisted by a Kerr magnon within a hybrid cavity magnomechanical system. We construct an effective Hamiltonian that accounts for photon-phonon squeezing through strong photon-magnon interaction and modulation over the driving on the photon mode. The effective Hamiltonian can be confirmed by the diagonalization of the system's Liouvillian superoperator. With the effective Hamiltonian and quantum Langevin equation, we provide a rigorous theoretical solution for the dynamical process of squeezing generation. Our finding indicates that the asymptotic stationary squeezing can be obtained by optimizing the squeezing quadrature operator, even when the covariance matrix of the system still varies with time. This squeezing level can exceed the maximum value under stable conditions. Moreover, our analysis reveals that a proper Kerr nonlinearity of the magnon can further promote the squeezing generation. Our work provides an extendable framework for generating squeezed states of two Gaussian modes with indirect coupling.
We investigate the generation of entanglement in a cavity magnomechanical system, which consists of magnons and cavity microwave photons and phonons; the magnon–photon and magnon–phonon couplings are achieved by the magnetic dipole interaction and the magnetostrictive interaction, respectively. By introducing magnon squeezing induced by magnon self-Kerr nonlinearity, the magnon–photon, magnon–phonon, and photon–phonon entanglements are enhanced compared with the case without inserting magnon squeezing. We find that an optimal parameter of the squeezing exists, which yields the maximum entanglement. This study provides a new idea for exploring the properties of quantum entanglement in cavity magnomechanical systems, and may have some potential applications in quantum state engineering.
The present study is based on a theoretically feasible scheme for the enhancement of entanglement between different bipartitions due to magnon squeezing in a two-cavity magnomechanical system, having two microwave cavity mode photons, a magnon mode, and phonon mode. The nonlinearity in the system is well enhanced owing to magnon squeezing, which is responsible for the enhancement of different bipartitions’ entanglement. By employing the standard Langevin approach, we found that the magnon squeezing parameter not only enhances the entanglement between directly coupled modes, but also has a considerable impact on indirectly coupled modes’ entanglement. In addition, we find the negative impact of the thermal bath for the mechanical mode on the generation of photon–phonon and magnon–phonon entanglements. Furthermore, magnon squeezing has shown a significant role in the entanglement robustness against thermal effects. Moreover, the tripartite entanglement among photon, magnon, and phonon is also considerably enhanced in the presence of magnon squeezing. This two-cavity magnomechanical system might be used in quantum tasks that require the enhancement of entanglement of indirectly coupled modes.
Quantum entanglement is a fundamental phenomenon in quantum information science and a crucial resource for quantum technologies such as precision sensing, secure communication, and computation. In hybrid cavity magno-optomechanical systems, entanglement among cavity photons, magnons, and phonons enables manipulation of quantum states across different modes via radiation pressure-based light-matter interaction. We propose a hybrid optomechanical cavity-magnonic setup with Yttrium iron garnet (YIG) sphere allowing magnons to couple with photons via magnetic-dipole interaction. The system also uses optomechanical and electrostatic interactions to entangle cavity photons and mechanical resonators. We focus on how the magnon nonlinear Kerr effect and varying coupling strengths influence entanglement dynamics. By analysing nonlinear effects alongside other coupling parameters, we identify optimal conditions for initiating and sustaining robust entanglement between the motional modes (phonons) of two Coulomb-coupled mechanical resonators. Our model predicts that adding Coulomb interaction and magnon coupling enhances the degree and tunability of entanglement, making it more resilient to thermal baths at 3 K. This study addresses how to optimize and sustain phonon-phonon entanglement in complex hybrid quantum systems. These findings offer insights relevant to developing quantum memories for continuous variable quantum information processing and other quantum technologies.
Abstract Based on the magnon Kerr effect, we show how to generate quantum squeezed states of magnons and photons in the cavity–magnon hybrid system. We find that the squeezing of magnons can be successfully induced by the magnon nonlinearity and the larger two-magnon effect strength will be beneficial to achieving the stronger squeezing of magnon. Resorting to the beam-splitter interaction between the magnons and photons, we further show that the squeezing of photons can be also effectively achieved. By properly choosing the system parameters, we demonstrate that the desired direction of the generated squeezing both for magnons and photons can be flexibly switched between orthogonal directions. Our scheme provides an alternative manipulation method to explore the quantum phenomena with nonlinear effects and also has significant potential applications in quantum precision measurement.
We investigate quantum coherence in a hybrid cavity magnomechanical system incorporating a squeezed-magnon drive. By analyzing the Gaussian quantum coherence of the cavity, magnonic, and mechanical subsystems, as well as the total system coherence, we identify the critical roles of phase control, coupling strength, drive power, and thermal noise. We show that the squeezing amplitude and phase precisely modulate the effective magnon frequency and damping, enabling phase-dependent enhancement and nonreciprocal transfer of coherence. Our systematic parameter analysis indicates that increasing driving power and photon-magnon coupling enhances quantum coherence, while thermal decoherence leads to its degradation. However, this effect is partially suppressed by the presence of magnon squeezing. The results show that squeezed magnons are a robust and tunable resource for controlling, stabilizing, and optimizing quantum coherence in cavity magnomechanical platforms, offering potential applications in hybrid magnonic systems and coherent quantum information processing.
Abstract A theoretical scheme is proposed to generate significant amount of photon-phonon entanglement and asymmetric steering in a cavity magnomechanical system, which is constituted by trapping a yttrium iron garnet sphere in a microwave cavity. By applying a blue-detuned microwave driving field, we obtain an effective Hamiltonian where the magnon mode acting as an engineered resevoir cools the Bogoliubov modes of microwave cavity mode and mechanical mode via a beam-splitter-like interaction. By this means, the microwave cavity mode and mechanical mode can be driven to a two-mode squeezed state in the stationary limit. Particularly, strong two-way and one-way photon-phonon asymmetric quantum steering can be obtained with even equal dissipation. It is widely divergent with the conventional proposal, where additional unbalanced losses or noises should be imposed on the two subsystems. Our finding may be significant to expand our understanding of the essential physics of asymmetric steering and extend the potential application of the cavity spintronics to device-independent quantum key distribution.