Noise Resilient 1SDIQKD for Practical Quantum Networks

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.