Topologically protected chainwise microwave-to-optical photon conversion interfaced by nitrogen-vacancy center ensembles

The pumped Su-Schrieffer-Heeger (SSH) model has been extensively employed for robust quantum state transfer (QST) due to its topologically protected edge channels that exhibit intrinsic resilience against local perturbations. Hybrid quantum systems have garnered significant research interest due to their unique capacity to collect distinct advantageous features that are inherently incompatible within individual physical platforms. Here, we propose a topological QST protocol for microwave (MW)-to-optical photon conversion in a synthesized SSH chain of a hybrid system. The topological structure is constructed by connecting superconducting resonators with optical cavities through interfaces of nitrogen-vacancy center ensembles. More importantly, we shorten the duration threshold of adiabatic evolution through power-law coupling engineering, and provide favorable conditions for high-efficiency MW-to-optical photon conversion, which significantly improves the scalability of the transducer with respect to both the system size and the number of converted photons. This approach paves the way for establishing high-efficiency quantum interfaces between localized MW quantum circuits and optical fiber networks, which is essential for long-distance quantum communication and distributed quantum computing.