Developing schemes for efficient and broadband frequency conversion of quantum signals is an ongoing challenge in the field of modern quantum information. The coherent conversion between microwave and optical signals is an especially important milestone towards long-distance quantum communication. In this work, we propose a two-stage conversion protocol, employing a resonant interaction between magnetic and mechanical excitations as a mediator between microwave and optical photons. Based on estimates for the coupling strengths under optimized conditions for yttrium iron garnet, we predict close to unity conversion efficiency without the requirement of matching cooperativities. We predict a conversion bandwidth in the regions of largest efficiency of the order of magnitude of the coupling strengths that can be further increased at the expense of reduced conversion efficiency.
Developing schemes for efficient and broadband frequency conversion of quantum signals is an ongoing challenge in the field of modern quantum information. The coherent conversion between microwave and optical signals is an especially important milestone towards long-distance quantum communication. In this work, we propose a two-stage conversion protocol, employing a resonant interaction between magnetic and mechanical excitations as a mediator between microwave and optical photons. Based on estimates for the coupling strengths under optimized conditions for yttrium iron garnet, we predict close to unity conversion efficiency without the requirement of matching cooperativities. We predict a conversion bandwidth in the regions of largest efficiency of the order of magnitude of the coupling strengths that can be further increased at the expense of reduced conversion efficiency.
As the main medium of quantum information, the frequency difference between optical and microwave photons is five orders of magnitude. Therefore, we generally improve the transmission efficiency of optical and microwave photons through coherent and bidirectional measures. The studies of the frequency conversion of optical and microwave photons in recent decades are all limited to Markovian approximations. In this paper we propose a scheme to achieve a two-stage frequency conversion between optical and microwave photons based on a hybrid of magnetic and mechanical excitations in non-Markovian environments. We estimate the interacting strengths under the optimal conditions of yttrium iron garnet and derive the conversion efficiency of optical and microwave photons through the scattering matrix. In all resonance modes, adjusting the defined complex cooperativities can get the conversion efficiency close to unity. The frequency conversion efficiency demonstrates a transition from Markovian to non-Markovian regimes by controlling the environmental spectral widths. This transition leads to enhancements of both the frequency conversion efficiency and conversion bandwidths, which originates from the excitation backflow obtained through the interaction between the systems and non-Markovian environments. In non-Markovian regimes, we predict that in areas with a large order of magnitude of optical pump power, the conversion bandwidths can be increased, but at the cost of a decrease in conversion efficiency, while decreasing the spectral widths can also achieve the same maximum conversion efficiency as in Markovian environments without requiring such a large optical pump power in non-Markovian regimes. Our scheme may provide an opportunity for the investigation of long-distance quantum communication for other non-Markovian quantum systems in quantum optics.
Generating usable output-entanglement in continuous variable systems can serve as a viable resource for improving applications in quantum information science. In this work, we show how to generate steady-state output-entanglement in a two-stage conversion setup between optical and microwave photon which employs resonantly coupled magnetic and mechanical excitations, as proposed in Phys. Rev. Applied 18, 044059 (2022). We show that the entanglement can be maximized for the same set of parameters which optimize the frequency-conversion efficiency, and that it can be leveraged for a teleportation-based state-transfer protocol for coherent input-states with fidelity close to unity. We propose an implementation based on an Yittrium Iron Garnet disk of micrometer scale, and use both simulation results and reasonable estimates to assess the performance under optimized conditions. We find a maximum teleportation fidelity of 0.75 for the proposed setup.
In this paper, we propose a scheme for frequency conversion between optical photons and microwave photons in non-Markovian environments using both magnetic and mechanical excitations as intermediate media. When the frequencies of optical photons, magnons, phonons, and microwave photons resonance, the conversion efficiency can be made close to reach 98.76% by adjusting the defined complex cooperativities, while in the case of Markovian, the conversion efficiency is 90.44%. By controlling the environmental spectral widths, the efficiency of frequency conversion exhibits a transition from Markovian regimes to non-Markovian regimes. This transformation simultaneously improves frequency conversion efficiency and conversion bandwidth, which is due to the excitation backflow generated by the interaction between the system and the non-Markovian environments. In the case, when the optical pump power in the non-Markovian regimes are of a large order of magnitude, the conversion bandwidth can be increased, but at the cost of reduced conversion efficiency. Our scheme improves the frequency conversion efficiency and bandwidth between optical photons and microwave photons, breaking the limitations of frequency conversion in Markovian environments and providing a new approach for long-distance quantum communication research of other non-Markovian quantum systems in quantum optics.
The successes of superconducting quantum circuits at local manipulation of quantum information and photonics technology at long-distance transmission of the same have spurred interest in the development of quantum transducers for efficient, low-noise, and bidirectional frequency conversion of photons between the microwave and optical domains. We propose to realize such functionality through the coupling of electrical, piezoelectric, and optomechanical resonators. The coupling of the mechanical subsystems enables formation of a resonant mechanical supermode that provides a mechanically-mediated, efficient single interface to both the microwave and optical domains. The conversion process is analyzed by applying an equivalent circuit model that relates device-level parameters to overall figures of merit for conversion efficiency η and added noise N. These can be further enhanced by proper impedance matching of the transducer to an input microwave transmission line. The performance of potential transducers is assessed through finite-element simulations, with a focus on geometries in GaAs, followed by considerations of the AlN, LiNbO3, and AlN-on-Si platforms. We present strategies for maximizing η and minimizing N, and find that simultaneously achieving η>50% and N<0.5 should be possible with current technology. Our comprehensive analysis of the full transduction chain enables us to outline a development path for the realization of high-performance quantum transducers that will constitute a new resource for quantum information science.
The successes of superconducting quantum circuits at local manipulation of quantum information and photonics technology at long-distance transmission of the same have spurred interest in the development of quantum transducers for efficient, low-noise, and bidirectional frequency conversion of photons between the microwave and optical domains. We propose to realize such functionality through the coupling of electrical, piezoelectric, and optomechanical resonators. The coupling of the mechanical subsystems enables formation of a resonant mechanical supermode that provides a mechanically mediated, efficient single interface to both the microwave and optical domains. The conversion process is analyzed by applying an equivalent circuit model that relates device-level parameters to overall figures of merit for conversion efficiency $\ensuremath{\eta}$ and added noise N. These can be further enhanced by proper impedance matching of the transducer to an input microwave transmission line. The performance of potential transducers is assessed through finite-element simulations, with a focus on geometries in GaAs, followed by considerations of the AlN, LiNbO3, and AlN-on-Si platforms. We present strategies for maximizing $\ensuremath{\eta}$ and minimizing N, and find that simultaneously achieving $\ensuremath{\eta}>50\mathrm{%}$ and N<0.5 should be possible with current technology. We find that the use of a mechanical supermode for mediating transduction is a key enabler for high-efficiency operation, particularly when paired with an appropriate microwave impedance-matching network. Our comprehensive analysis of the full transduction chain enables us to outline a development path for the realization of high-performance quantum transducers that will constitute a valuable resource for quantum information science.
Coherent interfaces between microwave-frequency quantum systems and low-loss optical links are essential for quantum networks. However, existing microwave-optical transducers often trade conversion efficiency against added noise, bandwidth, and device integrability. Here, we demonstrate coherent microwave-to-optical transduction based on magnon-exciton coupling in the layered antiferromagnet CrSBr. Driving the antiferromagnetic resonance with microwave signals imprints coherent modulation on a reflected optical probe, generating optical sidebands that are resonantly enhanced near excitonic transitions. While prior magnon-based approaches to microwave-to-optical transduction have typically relied on intrinsically weak off-resonant magneto-optical effects (e.g., Faraday rotation), our scheme exploits strong light-matter interactions at exciton resonances. Even in a bulk crystal without cavity enhancement, we observe coherent conversion over an intrinsically broadband window of ~ 300 MHz. We further show that multiple exciton-polariton resonances inherit the magnon-coupled response, suggesting a route to broaden the usable optical detuning range and to mitigate optical dissipation. Our results establish magnon-coupled excitons in layered magnets as a scalable platform for broadband microwave-optical interfaces, with pathways to higher cooperativity via reduced magnetic volume and cavity integration.