Quantum-Correlated Photon-Pair Source with Integrated Feedback Control in 45 nm CMOS

Integrated photonics provides scalability needed for useful photonic quantum information processing. Many optical resonators must be aligned to the same pump wavelength to produce sources of quantum-correlated photon pairs that drive such systems, but existing solutions rely on manual alignment or offline tuning based on external photodiodes and bulky off-chip electronics, limiting scalability. Here we demonstrate feedback control of four-wave mixing (stimulated and spontaneous) in a silicon microring using circuits integrated alongside photonics in a standard 45 nm CMOS foundry process. The carrier-sweepout-generated feedback signal enables in-situ operation in the photon-pair generation regime, which is a key building block enabling large-scale CMOS quantum-photonic systems-on-chip.