A Wafer-Scale Heterogeneous III-V-on-Silicon Nitride Quantum Photonic Platform

Heterogeneous integration of gain and strongly nonlinear materials with ultra-low-loss silicon nitride (SiN) photonics offers a route to scalable quantum circuits, but concurrent wafer-scale manufacturability, low interlayer loss, and high performance have been challenging to realize. Here we demonstrate a wafer-scale III-V-on-SiN quantum photonic platform that directly integrates III-V layers to foundry-fabricated SiN circuits. The SiN layer provides 200-300 nm thick waveguides with <1 dB/m loss and a mature passive photonics ecosystem, while III-V materials provide large χ^{left\(2right\)} and χ^{left\(3right\)} nonlinearities for parametric gain, frequency conversion and quantum light generation. Adiabatic interlayer couplers yield <25 mdB loss to InGaP waveguides and resonators with intrinsic quality factors exceeding 10⁶, enabling 15times brighter entanglement sources and efficient nonlinear conversion on SiN. Integrated components--including low-loss beam splitters, waveguide crossers, and tunable interferometers--are complemented by III-V lasers and InP photodetectors with amplifiers achieving up to 99⁺¹_-12\% quantum efficiency and 3 GHz bandwidth. This architecture unites ultra-efficient sources, nonlinear elements and detectors on a wafer-scale, low-loss platform, establishing a path toward large-scale, low-noise quantum photonic systems.