Researchers at NIST have developed a new control system for single-photon avalanche diodes (SPADs) that significantly improves their detection efficiency and reduces noise. The system works by generating electronic signals that cancel out interference caused by the SPAD’s own operation, allowing it to detect photons with much higher accuracy.
The new SPAD control system achieves detection efficiencies of up to 60%, which is close to the theoretical maximum for the detector material. It also reduces afterpulsing, a common issue where a detected photon can cause false signals, by an order of magnitude compared to other systems.
The improved SPAD performance is crucial for high-speed quantum communications, where secure encryption keys are generated using streams of individual photons. The new system is being developed in collaboration with DARPA’s Quiness initiative, which aims to demonstrate secure quantum key distribution at rates of 1-10 gigabits per second over distances of 1,000 to 10,000 km.
The next steps involve packaging the system for external collaborations and further testing to characterize its performance under various environmental conditions.
Source: https://www.nist.gov/news-events/news/2014/05/new-spad-control-system-high-efficiency-low-noise
Keywords: single-photon detection, semiconductor-based, avalanche diode (SPAD), afterpulsing, avalanche signal
