Integrated Control of Vacuum Fluctuation Channels for Bridging Entanglement Efficiency and Security in Quantum Networks

Quantum vacuum fluctuations are both a resource for entanglement generation and a source of decoherence that limits the security of quantum networks. Here we demonstrate, through a combined theoretical and numerical analysis, how the controlled shaping of vacuum electromagnetic modes enables high-fidelity and security-aware remote entanglement. Using experimentally realistic parameters from state-of-the-art platforms—including high-Q silicon nitride photonic crystal waveguides and superconducting circuit architectures—we calculate entanglement concurrence, generation rates, and fidelity under engineered versus unstructured environments. Our results show that Purcell-enhanced coupling, polarization filtering, and directional isolation yield order-of-magnitude improvements in entanglement efficiency while reducing leakage rates to below 1% of the total decay. We further translate these physical results into quantitative security metrics by bounding eavesdropper information through Holevo analyses, showing that secret key rates are only marginally degraded under engineered reservoirs. Crucially, this work establishes a dual-optimization principle: entanglement efficiency and cryptographic security can be co-optimized through vacuum-mode engineering. This framework provides both a physics-grounded theory and a roadmap for experimental implementation in next-generation quantum networks.