Quantum photon sources of high rate, brightness, and purity are increasingly desirable as quantum information systems are quickly scaled up and applied to many fields. Using a periodically poled lithium niobate microresonator on chip, we demonstrate photon-pair generation at high rates of 8.5 and 36.3 MHz using only 3.4 and 13.4 μW pump power, respectively, marking orders of magnitude improvement over the state of the art, across all material platforms. These results constitute the first direct measurement of the device's giant single photon nonlinearity. The measured coincidence to accidental ratio is well above 100 at those high rates and reaches 14682±4427 at a lower pump power. The same chip enables heralded single-photon generation at tens of megahertz rates, each with low autocorrelation g_{H}^{(2)}(0)=0.008 and 0.097 for the microwatt pumps, which marks a new milestone. Such distinct performance, facilitated by the chip device's noiseless and giant optical nonlinearity, will contribute to the forthcoming pervasive adoption of quantum optical information technologies.
Entanglement is a fundamental resource in quantum information processing. Several studies have explored the integration of sources of entangled states on a silicon chip, but the devices demonstrated so far require millimeter lengths and pump powers of the order of hundreds of milliwatts to produce an appreciable photon flux, hindering their scalability and dense integration. Microring resonators have been shown to be efficient sources of photon pairs, but entangled state emission has never been proven in these devices. Here we report the first demonstration, to the best of our knowledge, of a microring resonator capable of emitting time-energy entangled photons. We use a Franson experiment to show a violation of Bell’s inequality by more than seven standard deviations with an internal pair generation exceeding 107 Hz. The source is integrated on a silicon chip, operates at milliwatt and submilliwatt pump power, emits in the telecom band, and outputs into a photonic waveguide. These are all essential features of an entangled state emitter for a quantum photonic network.