Noise Resilient 1SDIQKD for Practical Quantum Networks

TL;DR

This paper extends 1SDI-QKD security analysis to realistic noisy channels, identifies noise thresholds, and proposes entanglement purification to maintain secure keys in practical quantum networks.

Contribution

It introduces a comprehensive noise model for 1SDI-QKD, quantifies noise impact on security, and demonstrates entanglement purification as a practical mitigation strategy.

Findings

Dephasing noise is most tolerable among studied noise types.

Security can be lost even with high entanglement levels.

Entanglement purification effectively restores security in noisy conditions.

Abstract

One-sided device-independent quantum key distribution (1SDI-QKD) offers a practical middle ground between fully device-independent protocols and standard QKD, achieving security with detection efficiencies as low as 50.1\% on the untrusted side. However, prior analyses assumed idealized channels, neglecting realistic noise sources. We extend the 1SDI-QKD framework to include amplitude damping, dephasing, and depolarizing noise, quantifying their impact on secure key rates and efficiency requirements. Our results reveal a clear noise hierarchy: dephasing is most tolerable (secure keys achievable at 70\% efficiency with 30\% noise), while amplitude damping and depolarizing noise dramatically elevate requirements to over 90\%. Crucially, we find that security is lost while substantial entanglement remains (concurrence $C \approx 0.7$--$0.8$), demonstrating that steering violation, not merely entanglement, determines 1SDI-QKD security. To mitigate noise effects, we integrate the BBPSSW entanglement purification protocol, showing that 2--4 rounds can restore positive key rates in otherwise insecure regimes. Our resource overhead analysis reveals that effective key rates peak at moderate purification depths; excessive rounds become counterproductive. These findings establish practical boundaries for deploying 1SDI-QKD over metropolitan-scale quantum networks.