Quantum-Secured Supply Chain: 3D QKD Network

A full 3D mesh of BB84 quantum-key-distribution channels linking factories, ports, hubs, warehouses and retail nodes across a global supply chain. Photons visibly travel each link while the engine computes real per-channel physics — fiber attenuation, sifted key rate, QBER and the privacy-amplification bound — then aggregates it into a network-wide secure key rate, average QBER, compromised-link count and an estimated residual risk. Rebuild the topology, stretch the network span, dial up an eavesdropper, and watch which links stop yielding usable key.