Trigger-disabling Acquisition System for Quantum Key Distribution failsafe against Self-blinding

TL;DR

This paper presents an FPGA-based trigger-disabling system for quantum key distribution detectors, enhancing security by preventing self-blinding and optimizing detector speed and efficiency.

Contribution

Introduces a novel FPGA-driven feedback circuitry that dynamically manages detector triggers, improving security and performance in quantum key distribution systems.

Findings

Reduces self-blinding risk in QKD detectors

Enables operation at maximum detector speed

Improves security and efficiency of QKD setups

Abstract

Modern single-photon detectors based on avalanche photodiodes offer increasingly higher triggering speeds, thus fostering their use in several fields, prominently in the recent area of Quantum Key Distribution. To reduce the probability of an afterpulse, these detectors are usually equipped with a circuitry that disables the trigger for a certain time after a positive detection event, known as dead time. If the acquisition system connected to the detector is not properly designed, efficiency issues arise when the triggering rate is faster than the inverse of detector's dead-time. Moreover, when this happens with two or more detectors used in coincidence, a security risk called "self-blinding" can jeopardize the distribution of a secret quantum key. In this paper we introduce a trigger-disabling circuitry based on an FPGA-driven feedback loop, so to avoid the above-mentioned inconveniences. In the regime of single-photon-attenuated light, the electronics dynamically accept a trigger only after detectors' complete recovery from dead-time. This technique proves useful to work with detectors at their maximum speed and to increase the security of a quantum key distribution setup.