Heterogeneous Single-photon Transistor with Rydberg Atoms

The development of practical quantum networks and scalable photonic quantum information processing crucially depends on the ability to execute high-fidelity and coherent operations between photons of different wavelengths. While approaches based on quantum interference can implement many quantum operations, they are inherently limited to identical photons and thus are insufficient for the frequency-matching requirements of heterogeneous quantum systems. Rydberg atomic systems provide a powerful platform for achieving strong photonphoton nonlinearities capable of overcoming this limitation. Here, we report a heterogeneous single-photon switch and transistor based on Rydberg atoms, where a single gate photon at 795 nm controls the transmission of subsequent target photons at 780 nm. Our devices achieve a post-selected extinction ratio of ϵ = 0.09(3) for the switch, alongside a transistor gain of G = 26(2) achieved by leveraging a Förster-resonance-enhanced cross-state interaction. This work establishes a practical pathway towards building frequency-multiplexed quantum interfaces, a key component for interconnecting disparate physical platforms in future hybrid quantum networks.