SPICE · Scalable Photon-Number-Resolving Integrated Cryogenic Electronics

Large-scale configurations of superconducting nanowire single-photon detectors (SNSPDs) are essential for quantum technologies such a photonic quantum computing, quantum communication and quantum sensing. Furthermore, spatial arrays of SNSPDs are ideally suited to light-starved applications such as deep-space optical communication (DSOC), single-photon imaging, microscopy, and spectroscopy. While SNSPDs offer near-unity efficiency, high timing resolution, and low noise, their potential is constrained by the lack of scalable photon-number-resolving (PNR) readout electronics. Indeed, the true bottleneck is not reliable detector fabrication but rather the wiring and signal processing required for large-scale SNSPD systems. This project will deliver in-situ cryogenic CMOS-based signal processing, enabling intrinsic PNR within each detector and signal processing from multiple detectors. By directly processing detection signals at cryogenic temperatures, we eliminate the need for individual high-bandwidth readout lines, drastically reducing footprint and heat load, thereby improving scalability. Furthermore, instead of traditional 50-ohm impedance matching, we leverage SNSPD signal transients and apply pre-programmed low-power processing to extract only the essential information from the detectors. This novel approach to data reduction at the point of detection has never been applied to SNSPD arrays but is a crucial step toward their widespread application. To achieve these goals, we leverage the research output of the ERC-StG project Quantum Engineering Superconducting Array Detectors in Low Light Applications (QuESADILLA) and a network of major European commercial and academic stakeholders. By addressing the core scalability limitations, this project will unlock the full potential of SNSPD arrays, paving the way for large-scale, energy-efficient single-photon detection systems tailored for next-generation quantum technologies and imaging solutions.