Optomicrowave entanglement and optomagnonic entanglement have significant applications in constructing hybrid quantum network and optical controlling magnons. In this paper, a theoretical scheme of enhancing optomicrowave and optomagnonic entanglements is proposed, based on a coherent-feedback-assisted optomagnomechanical (OMM) system. By inserting a thin membrane between the input-output mirror and the high-reflective-mirror-attached YIG bridge, the system consists of four kinds of modes: optical mode, microwave mode, mechanical mode, and magnon mode. In this system, optical mode and microwave mode interact with each other through the mechanical mode, while the magnon mode couples with the microwave mode through magnetic-dipole interaction. The entanglement is originally generated between optical mode and phonon mode under the two-mode squeezing mechanism (blue-detuned driven), then the generated entanglement is transferred to the optical mode and microwave mode through the state transfer mechanism (red-detuned driven) between the microwave mode and phonon mode and is further transferred to the optical mode and magnon mode by the magnetic-dipole interaction between the microwave mode and magnon mode. Adopting the negative logarithm criterion, the variations of the optomicrowave and optomagnonic entanglements with detuning, coupling strength, and decay rate are thoroughly investigated. Furthermore, the optimal coherent feedback parameters and the physical mechanisms of generating and transferring entanglement are analyzed, and the entanglement enhancements by adding the feedback loop are discussed. The results show that after adding coherent feedback, optomicrowave entanglement and optomagnonic entanglement can be enhanced effectively within a wide range of parameters and the enhancement can also be well maintained. Our findings provide a theoretical basis for connecting different nodes (different physical systems) to construct hybrid quantum networks, flexibly controlling the quantum properties of magnons, and preparing macroscopic quantum states.
Optomicrowave entanglement and optomagnonic entanglement have significant applications in constructing hybrid quantum network and optical controlling magnons. In this paper, a theoretical scheme of enhancing optomicrowave and optomagnonic entanglements is proposed, based on a coherent-feedback-assisted optomagnomechanical (OMM) system. By inserting a thin membrane between the input-output mirror and the high-reflective-mirror-attached YIG bridge, the system consists of four kinds of modes: optical mode, microwave mode, mechanical mode, and magnon mode. In this system, optical mode and microwave mode interact with each other through the mechanical mode, while the magnon mode couples with the microwave mode through magnetic-dipole interaction. The entanglement is originally generated between optical mode and phonon mode under the two-mode squeezing mechanism (blue-detuned driven), then the generated entanglement is transferred to the optical mode and microwave mode through the state transfer mechanism (red-detuned driven) between the microwave mode and phonon mode and is further transferred to the optical mode and magnon mode by the magnetic-dipole interaction between the microwave mode and magnon mode. Adopting the negative logarithm criterion, the variations of the optomicrowave and optomagnonic entanglements with detuning, coupling strength, and decay rate are thoroughly investigated. Furthermore, the optimal coherent feedback parameters and the physical mechanisms of generating and transferring entanglement are analyzed, and the entanglement enhancements by adding the feedback loop are discussed. The results show that after adding coherent feedback, optomicrowave entanglement and optomagnonic entanglement can be enhanced effectively within a wide range of parameters and the enhancement can also be well maintained. Our findings provide a theoretical basis for connecting different nodes (different physical systems) to construct hybrid quantum networks, flexibly controlling the quantum properties of magnons, and preparing macroscopic quantum states.
The optomagnomechanical system, which involves flexible nonlinearities, is one of the promising physical platforms for studying the preparation and manipulation of quantum entanglements, as well as the construction of hybrid quantum networks. A scheme for entanglement enhancement and quadripartite entanglement generation is proposed, based on a cascaded optomagnomechanical system. On the one hand, optomicrowave and optomagnonic entanglements within the two subsystems are investigated, and their parameter dependence, such as detuning, decay, coupling strength, transmission efficiency, and temperature is discussed. On the other hand, the parameter conditions for achieving optimal optomicrowave and optomagnonic quadripartite entanglements are also obtained. The results show that significant enhancement of optomicrowave and optomagnonic entanglements in the second cavity can be obtained in a certain range of parameters. Under optimized parameter conditions, optomicrowave and optomagnonic quadripartite entanglements can be generated throughout the entire cascaded system. This research provides a theoretical basis for the manipulation of quantum entanglement, the transmission of the magnon's state, and the construction of hybrid quantum networks involving different physical systems.
We demonstrate a scheme to realize high-efficiency entanglement of two microwave fields in a dual opto-magnomechanical system. The magnon mode simultaneously couples with the microwave cavity mode and phonon mode via magnetic dipole interaction and magnetostrictive interaction, respectively. Meanwhile, the phonon mode couples with the optical cavity mode via radiation pressure. Each magnon mode and optical cavity mode adopts a strong red detuning driving field to activate the beam splitter interaction. Therefore, the entangled state generated by the injected two-mode squeezed light in optical cavities can be eventually transferred into two microwave cavities. A stationary entanglement E a 1 a 2 =0.54 is obtained when the input two-mode squeezed optical field has a squeezing parameter r = 1. The entanglement E a 1 a 2 increases as the squeezing parameter r increases, and it shows the flexible tunability of the system. Meanwhile, the entanglement survives up to an environmental temperature about 385 mK, which shows high robustness of the scheme. The proposed scheme provides a new mechanism to generate entangled microwave fields via magnons, which enables the degree of the prepared microwave entanglement to a more massive scale. Our result is useful for applications which require high entanglement of microwave fields like quantum radar, quantum navigation, quantum teleportation, quantum wireless fidelity (Wi-Fi) network, etc.
Quantum entanglement and quantum coherence generated from the optomagnomechanical system are important resources in quantum information and quantum computation. In this paper, a scheme for flexibly generating optomagnonic quantum entanglement and quantum coherence difference is proposed, based on a double-cavity-optomagnomechanical system. The parameter dependencies of the bipartite optomagnonic entanglement, the genuine tripartite optomagnonic entanglement, the quantum coherence difference, and the stability of the system, are investigated intensively. The results show that this scheme endows the magnon more flexibility to choose different mechanisms, under the condition of maintaining the system stable. This work is valuable for connecting different nodes in hybrid quantum networks and manipulating the magnon states with light in the future.
Abstract Finding new strategies for the generation and preservation of quantum resources, e.g. entanglement between spatially separated macroscopic systems enables reliable and fertile platforms to study both fundamental quantum physics and fruitful applications such as quantum networks and distant quantum information processing. Here, we want to address how to generate magnon-magnon entanglement (MME) in an optomagnonic system based on the optical Bell-state measurement. To do so, we consider a hybrid optomagnonic system comprising of two identical, but distant dissipative microwave cavities, each containing a ferromagnetic YIG sphere and a superconducting qubit. Besides, each subsystem is driven via an external laser field. We numerically simulate the solution of the corresponding master equation and discuss the time-dependent as well as the steady state entanglement between the distant magnon modes at different interaction regime. Also, the fidelity of the generated entangled states is studied in detail. Generally, the dissipative environmental effects plague the MME, however, it is possible to generate a considerable amount of MME even at the steady state regime. Also, the results show that the robust MME may be enhanced by applying a relatively strong external pump decreasing the relative magnon damping rate as well as increasing the relative qubit-photon coupling strength, while some other parameters involved in the model, i.e. the atomic damping rate and detuning parameter do not considerably affect the amplitude (the maximum value) of MME. Exceptionally, although the magnon damping rate decreases the amount of MME, the entanglement stability takes place in a longer time interval in the strong magnonic damping regime. Moreover, the maximum of the steady state entanglement may be obtained in the moderate magnon-photon coupling regime provided that the system is driven by strong external pumps. Furthermore, the system can generate robust MME at steady state, especially in the small detuning regime. Our further investigations show that the system can provide relatively high-fidelity magnonic entangled states even in the presence of inevitable environmental effects. The proposed model offers an attractive platform for the generation of quantum resources to establish long-distance quantum networks based on magnonic and photonic systems.
We propose a scheme to generate entanglement between microwave fields and achieve strong squeezing of the optical output field in an opto-magnomechanical ring cavity. The system consists of two elastic yttrium iron garnet crystals with attached mirror pads inside two separate microwave cavities, and an extra fixed mirror outside the microwave cavities is utilized to complete the optical ring cavity with the two mirror pads. A magnon mode supported by the yttrium iron garnet crystal couples directly to the microwave cavity mode via magnetic dipole interaction and couples indirectly to the optical cavity mode via magnomechanical displacement, which is caused by magnetostrictive interaction and also couples the magnon mode to a phonon mode. A squeezed light is fed into the ring cavity to entangle the two phonon modes. To activate the beam splitter interaction, each magnon mode and optical cavity mode is driven by a strong red-detuned driving field. Consequently, the stationary entanglement between the two microwave cavities is obtained. The transfer efficiency of the entanglement is [Formula: see text]. To ensure the squeezing of the magnon mode generated by magnetostrictive interaction transferred into the optical field, we remove two microwave cavities. The squeezing of the optical output field can reach up to [Formula: see text] dB at 10 mK and survives up to an environmental temperature about 500 mK. Our scheme may find various useful applications in quantum wireless fidelity network and the enhancement of sensitivity of measurements.
Quantum entanglement is a key resource for performing quantum computing and building quantum communication networks. By injecting a microwave-optical dual-mode entanglement field into the system, as well as pumping the optical and microwave cavities, and by appropriately choosing the detuning relationship between the pumping field and the modes, it is shown in this work that microwave-phonon entanglement Eab and magnon-optics entanglement Ecm can be generated simultaneously in the cavity opto-magnomechanic system, and the entanglement can be in a steady state. Specifically, the model is based on a hybrid quantum system of magnons, where a microwave-light entanglement generated by an optically pulsed superconducting electro-optical device through spontaneous parametric down-conversion process is injected as the intracavity field, and a blue-detuned microwave field is used to excite the magnon modes to produce magnon-phonon entanglement. Through the interaction between an optomechanical beam splitter and microwave-magnon state-swap, steady microwave-phonon entanglement Eab and magnon-optics entanglement Ecm are successfully realized. The entanglement Eab and Ecm in the system are analyzed using the logarithmic negativity. The effects of several parameters of the system, such as environment temperature, coupling strength and dissipation rate, on the degree of entanglement are investigated. In particular, the entanglement Eab and Ecm generated in this system can exist both simultaneously and individually. Especially when gam = 0, the entanglement Eab and Ecm still exist. Moreover, directly injecting entangled microwave-light into the system can significantly enhance the robustness of the entanglement against temperature, which will have broad application prospects in quantum information processing in quantum networks and hybrid quantum systems. Notably, the entanglement Eab and Ecm exist even at a temperature of 1.3 K. Our research has potential value for applications in the fields of quantum information processing and quantum networks.