We present an active anti-latching system for superconducting nanowire single-photon detectors. We experimentally test it against a bright-light attack, previously used to compromise security of quantum key distribution. Although our system detects continuous blinding, the detector is shown to be partially blindable and controllable by specially tailored sequences of bright pulses. Improvements to the countermeasure are suggested.

No abstract

Today, a lab-on-a-chip is one of the most promising ways to create sensor devices for gas and liquid analysis for environmental monitoring, early diagnosis, and treatment effectiveness assessment. On the one hand, this requires a large number of measurements and, on the other hand, involves minimum consumption of the test analytes. Combination of highly sensitive photonic integrated circuits (PICs) with microfluidic channels (MFCs) is necessary to solve this problem. In this work, PICs based on a silicon nitride platform integrated with MFCs for studying liquids and gases were developed. Different concentrations of isopropanol in de-ionized water were used as the analyte. Based on this, the sensitivity (S) and detection limit (DL) of the analyzed solution were evaluated. Entire system calibration was carried out to calculate S and DL, considering experimental and numerical simulation data. This development may be of interest as a promising platform for environmental monitoring and realization of point-of-care strategy for biomedical applications.