We propose two schemes to achieve remote entanglement distribution between two mechanical nodes with a significant frequency mismatch, based on optomechanical systems. The first scheme utilizes the physical mechanism to redistribute the quantum entanglement initially established in a dispersively-coupled optomechanical system with a megahertz mechanical resonance to a distant optomechanical system which embodies the tripleresonant interaction induced by the scattering of gigahertz mechanical phonon. We also provide a fast optical pulse protocol to realize the long-distance entanglement distribution from the optomechanical system supporting the gigahertz mechanical mode to the megahertz mechanical mode included in a distant optomechanical system. Specifically, these two schemes respectively demonstrate the megahertz-to-gigahertz and gigahertz-tomegahertz entanglement distribution in the quantum network of optical photons and phonons. This work may facilitate the application of various mechanical systems in hybrid quantum network-based quantum technologies and fundamental physical research.
We propose two schemes to achieve remote entanglement distribution between two mechanical nodes with a significant frequency mismatch, based on optomechanical systems. The first scheme utilizes the physical mechanism to redistribute the quantum entanglement initially established in a dispersively-coupled optomechanical system with a megahertz mechanical resonance to a distant optomechanical system which embodies the tripleresonant interaction induced by the scattering of gigahertz mechanical phonon. We also provide a fast optical pulse protocol to realize the long-distance entanglement distribution from the optomechanical system supporting the gigahertz mechanical mode to the megahertz mechanical mode included in a distant optomechanical system. Specifically, these two schemes respectively demonstrate the megahertz-to-gigahertz and gigahertz-tomegahertz entanglement distribution in the quantum network of optical photons and phonons. This work may facilitate the application of various mechanical systems in hybrid quantum network-based quantum technologies and fundamental physical research.
A quantum network that distributes and processes entanglement would enable powerful new computers and sensors. Optical photons with a frequency of a few hundred terahertz are perhaps the only way to distribute quantum information over long distances. Superconducting qubits on the other hand, which are one of the most promising approaches for realizing large-scale quantum machines, operate naturally on microwave photons that have roughly 40,000 times less energy. To network these quantum machines across appreciable distances, we must bridge this frequency gap and learn how to generate entanglement across widely disparate parts of the electromagnetic spectrum. Here we implement and demonstrate a transducer device that can generate entanglement between optical and microwave photons, and use it to show that by detecting an optical photon we add a single photon to the microwave field. We achieve this by using a gigahertz nanomechanical resonance as an intermediary, and efficiently coupling it to optical and microwave channels through strong optomechanical and piezoelectric interactions. We show continuous operation of the transducer with 5% frequency conversion efficiency, and pulsed microwave photon generation at a heralding rate of 15 hertz. Optical absorption in the device generates thermal noise of less than two microwave photons. Joint measurements on optical photons from a pair of transducers would realize entanglement generation between distant microwave-frequency quantum nodes. Improvements of the system efficiency and device performance, necessary to realize a high rate of entanglement generation in such networks are within reach.
Abstract A theoretical scheme for the stable entanglement generation of two remote mechanical modes is introduced. Two identical optomechanical systems, each constituting a single‐mode optical field as well as a qubit and a moveable mirror driven by an external pump field, are considered. To make the model more realistic, atomic, photonic, and phononic dissipations are considered. The time‐dependent state of each subsystem is obtained, analytically. Then, by an appropriate Bell‐state measurement (BSM) on the state of the whole system (first approach), the entanglement of two mechanical modes is created. As a second parallel approach, appropriate atomic measurement is applied after the BSM. According to these numerical simulations via concurrence, the noteworthy features are as follows. There exists optimum value of photon–phonon coupling strength for obtaining the steady‐state entanglement; by choosing appropriate values of dissipation, photon–phonon coupling, and pump amplitude, a significant degree and stable entanglement between the two mechanical modes are accessible. The present scheme opens new practical perspectives in constructing stable entanglement between two remote mechanical modes and can be helpful to realize quantum memories for quantum information processing and establishing long‐distance quantum communication networks.
A quantum network consisting of magnonic and mechanical nodes connected by light is proposed.Recent years have witnessed a significant development in cavity magnonics based on collective spin excitations in ferrimagnetic crystals, such as yttrium iron garnet (YIG).Magnonic systems are considered to be a promising building block for a future quantum network.However, a major limitation of the system is that the coherence time of the magnon excitations is limited by their intrinsic loss (typically in the order of 1 μs for YIG).Here, we show that by coupling the magnonic system to a mechanical system using optical pulses, an arbitrary magnonic state (either classical or quantum) can be transferred to and stored in a distant long-lived mechanical resonator.The fidelity depends on the pulse parameters and the transmission loss.We further show that the magnonic and mechanical nodes can be prepared in a macroscopic entangled state.These demonstrate the quantum state transfer and entanglement distribution in such a novel quantum network of magnonic and mechanical nodes.Our work shows the possibility to connect two separate fields of optomagnonics and optomechanics, and to build a long-distance quantum network based on magnonic and mechanical systems.
Entanglement between distant massive mechanical oscillators is of particular interest in quantum-enabled devices due to its potential applications in distributed quantum information processing. Here we propose how to achieve nonreciprocal remote entanglement between two spatially separated mechanical oscillators within a cascaded optomechanical configuration, where the two optomechanical resonators are indirectly coupled through a telecommunication fiber. We show that by selectively spinning the optomechanical resonators, one can break the time-reversal symmetry of this compound system via the Sagnac effect, and more excitingly, enhance the indirect couplings between the mechanical oscillators via the individual optimizations of light-motion interaction in each optomechanical resonator. This ability allows us to generate and manipulate nonreciprocal entanglement between distant mechanical oscillators, that is, entanglement can be achieved only through driving the system from one specific input direction but not the other. Moreover, in the case of two frequency-mismatched mechanical oscillators, it is also found that the degree of the generated nonreciprocal entanglement is counterintuitively enhanced in comparison with its reciprocal counterparts, which are otherwise unattainable in static cascaded systems with a single-tone driving laser. Our work, which is well within the feasibility of current experimental capabilities, provides an enticing opportunity to explore the nonclassical correlations between distant massive objects and facilitates a variety of emerging quantum technologies ranging from quantum information processing to quantum sensing.
In this paper, we consider the quantum repeater protocol for distributing the entanglement to two distant three-level atoms. In this protocol, we insert six atoms between two target atoms, such that the eight considered atoms are labeled by 1,2,⋯8, while only each two adjacent atoms (i,i+1) with i=1,3,5,7 are entangled. Initially, the separable atomic pair states (1,4) and (5,8) become entangled by performing interaction between atoms (2,3) and (6,7) in two optomechanical cavities, respectively. Then, via performing appropriate interaction between atoms (4,5) in an optical cavity quantum electrodynamics approach, the target atoms (1,8) finally become entangled. Throughout this investigation, the effects of mechanical frequency and optomechanical coupling strength to the field modes on the produced entanglement and the related success probability are evaluated. It is shown that the time period of produced entanglement can be developed by increasing the mechanical frequency. Also, the maximum of the success probability of atoms (1,8) is increased by decreasing the optomechanical coupling strength to the field modes in most cases.
Generating long-distance quantum entanglement is crucial for advancing quantum information processing. In this work, we propose a protocol for generating remote magnon-phonon entanglement in a hybrid waveguide-magnomechanical system, where multiple spatially separated magnon modes couple to a common waveguide while interacting with their respective phonon modes. By applying tailored pulsed drives and engineering the magnomechanical interactions, our scheme enables the creation of diverse long-distance and dynamically stable entanglement. Beyond basic magnon-phonon two-mode entanglement, it supports genuine multimode entanglement between a single phonon and multiple magnons, bipartite entanglement between a single magnon and multiple phonons, as well as genuine four-mode entanglement involving two magnons and two phonons. Moreover, we show that dissipative magnon-magnon interactions mediated by traveling photons can generate substantially stronger remote entanglement than coherent couplings. Our work provides an experimentally feasible scheme for the remote generation of magnon-phonon entanglement.