Secure detection in quantum key distribution by real-time calibration of receiver

TL;DR

This paper introduces a real-time calibration method for single photon detectors in quantum key distribution, enhancing security by accurately estimating detection efficiency and safeguarding against detector-based attacks.

Contribution

A novel real-time calibration technique for detector efficiency estimation in quantum key distribution, ensuring security against detector exploitation attacks.

Findings

Secure key rate can be calculated with estimated detector efficiency.

The method is effective for detectors with non-ideal, imperfect efficiencies.

Adding optical components ensures security even with detector imperfections.

Abstract

The single photon detection efficiency of the detector unit is crucial for the security of common quantum key distribution protocols like Bennett-Brassard 1984 (BB84). A low value for the efficiency indicates a possible eavesdropping attack that exploits the photon receiver's imperfections. We present a method for estimating the detection efficiency, and calculate the corresponding secure key generation rate. The estimation is done by testing gated detectors using a randomly activated photon source inside the receiver unit. This estimate gives a secure rate for any detector with non-unity single photon detection efficiency, both inherit or due to blinding. By adding extra optical components to the receiver, we make sure that the key is extracted from photon states for which our estimate is valid. The result is a quantum key distribution scheme that is secure against any attack that exploits detector imperfections.