QUANTUM ENTANGLEMENT AND ITS APPLICATIONS IN SECURE COMMUNICATION PROTOCOL'S

Abstract

Quantum entanglement has emerged as a foundational resource for secure communication, enabling cryptographic security that is grounded in the laws of physics rather than computational complexity. This study presents a systems-level investigation of entanglement-based secure communication protocols, integrating physical channel modeling, detector imperfections, Bell-inequality diagnostics, adversarial strategies, and cryptographic post-processing within a unified analytical framework. Using a large-scale simulation dataset, we evaluate the performance and security of multiple entanglement-based protocols under realistic noise, loss, and attack conditions. The results demonstrate that secure key generation is not determined by protocol choice alone but arises from the joint interaction of channel attenuation, detector efficiency, background noise, and the strength of nonlocal quantum correlations. In particular, the CHSH Bell parameter is shown to be a strong predictor of both cryptographic viability and throughput, reframing Bell violation as an operational security resource rather than a purely foundational test. The analysis further reveals threshold-like security collapse at long distances, highlighting the dominant influence of physical-layer constraints. Additionally, several adversarial strategies are shown to preserve low error rates while silently undermining security assumptions, underscoring the limitations of QBER-only diagnostics. Together, these findings provide a comprehensive, experimentally grounded perspective on the design of scalable quantum communication systems and offer practical guidance for the development of robust, next-generation quantum networks.