Optimizing Continuous-Wave-Pumped Entanglement-based QKD in Noisy Environments

TL;DR

This paper investigates the effects of extreme noise on continuous-wave-pumped entanglement-based QKD systems and develops an adaptive model to optimize performance in noisy environments.

Contribution

It reveals significant variations in detector parameters under noise and introduces a noise-adaptive model for improved QKD system performance.

Findings

Detector parameters vary significantly under extreme noise.

The adaptive model enables reliable performance characterization.

Optimization improves QKD robustness in noisy conditions.

Abstract

Quantum key distribution (QKD) has emerged as a promising solution to protect current cryptographic systems against the threat of quantum computers. As QKD transitions from laboratories to real-world applications, its implementation under various environmental conditions has become a pressing challenge. Major obstacles to practical QKD implementation are the loss of photons in the transmission media and the presence of extreme noise, which can severely limit long-range transmission. In this paper, we investigate the impact of extreme noise on QKD system parameters, including timing jitter, rate-dependent timing shifts, changes in effective detector dead time, and rate-dependent detection efficiency. Contrary to manufacturers' specifications, which assume these parameters to be constant, we demonstrate that these parameters exhibit significant variations in extreme noise conditions. We show that changes in these parameters play a key role in determining system performance in noisy environments. To address these nonidealities, we develop a model that adapts to detector-dependent timing distortions and recovery effects. In particular, our model is independent of source parameters and can be implemented using data from the detection unit. Our results show that the model enables reliable characterization and optimization of QKD performance under strong noise.