High-resolution coincidence counting system for large-scale photonics applications

The increasing complexity of recent photonic experiments challenges the development of efficient multichannel coincidence counting systems with high-level functionality. Here, we report a coincidence unit able to count detection events ranging from single to 16-fold coincidences with full channel-number resolution. The device operates within sub-100-ps coincidence time windows, with a maximum input frequency of 1.5 GHz and an overall jitter of less than 10 ps. The unit high-level timing performance renders it suitable for quantum photonic experiments employing low-timing-jitter single-photon detectors. Additionally, the unit can be used in complex photonic systems to drive feed-forward loops. We demonstrate the developed coincidence counting unit in photon-number-resolving detection to directly quantify the statistical properties of light, specifically coherent and thermal states, with a fidelity exceeding 0.999 up to 60 photons.