# A countermeasure against bright-light attack on superconducting nanowire single-photon detector in quantum key distribution

## TL;DR

This paper introduces an active anti-latching system for superconducting nanowire single-photon detectors to defend against bright-light attacks in quantum key distribution, highlighting its partial effectiveness and proposing improvements.

## Contribution

The paper presents a novel active countermeasure against bright-light attacks on superconducting nanowire detectors, with experimental validation and suggested enhancements.

## Key findings

- The system detects continuous blinding attempts.
- Detectors remain partially controllable by tailored bright pulses.
- Proposed improvements aim to enhance security against such attacks.

## Abstract

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.