Cybersecure Synchronisation of Entangled Quantum Neural Networks With Reconfigurable Intelligent Surface and Quantum Key Distribution for 6G Holographic Communications

ABSTRACT This paper presents a cybersecure hybrid quantum–classical architecture for synchronising distributed quantum neural networks (QNNs) in 6G holographic communications. The proposed framework targets secure, low‐latency and high‐fidelity end‐to‐end operation under realistic noise and adversarial conditions. Multipartite Greenberger–Horne–Zeilinger (GHZ) entanglement supports gradient‐consensus synchronisation, regularised by von Neumann entropy and trace distance. Holographic tensor teleportation is executed over reconfigurable intelligent surface (RIS)‐assisted midhaul links protected by quantum key distribution (QKD). Joint optimisation of QNN parameters and RIS phases targets high end‐to‐end fidelity under noise. Qiskit simulations averaged over 100 trials achieve , and , with 22.5 ms end‐to‐end latency. Compared with reduced baselines without GHZ synchronisation or without RIS control, fidelity improves by 20%–28% and synchronisation divergence decreases by about 90%. Scalability, security stress scenarios, classical‐feedback impairments, hyperparameter sensitivity and noisy intermediate‐scale quantum (NISQ)‐oriented error mitigation are all evaluated. The architecture scales gracefully to distributed units with only 7% fidelity reduction, whereas mitigation improves fidelity by 7%–11% under moderate noise. Overall, the RIS‐QKD‐GHZ integration enables secure, low‐latency and scalable quantum–classical 6G networking.