Noisy pre-processing facilitating a photonic realisation of device-independent quantum key distribution

TL;DR

This paper introduces a noise-adding protocol to relax detection efficiency requirements in photonic device-independent quantum key distribution, enabling more feasible experimental implementations while maintaining security.

Contribution

The authors propose a novel noise pre-processing method that reduces the detection efficiency threshold needed for secure photonic device-independent quantum key distribution.

Findings

Explicit bounds on minimal detection efficiency for secure key distribution

Protocol effectively relaxes efficiency thresholds in realistic setups

Maintains provable security despite added artificial noise

Abstract

Device-independent quantum key distribution provides security even when the equipment used to communicate over the quantum channel is largely uncharacterized. An experimental demonstration of device-independent quantum key distribution is however challenging. A central obstacle in photonic implementations is that the global detection efficiency, i.e., the probability that the signals sent over the quantum channel are successfully received, must be above a certain threshold. We here propose a method to significantly relax this threshold, while maintaining provable device-independent security. This is achieved with a protocol that adds artificial noise, which cannot be known or controlled by an adversary, to the initial measurement data (the raw key). Focusing on a realistic photonic setup using a source based on spontaneous parametric down conversion, we give explicit bounds on the minimal required global detection efficiency.