Curator's Take
This article marks the first long‑term, field‑tested deployment of entanglement‑based QKD inside a real financial network, showing that a fully automated source can sustain 63 kb/s secure keys over a 22 km fiber link for months with >93 % uptime and sub‑2 % quantum bit error rates. By eliminating the need for auxiliary guide lasers or external timing references, the system demonstrates a level of integration and robustness that bridges laboratory demonstrations—such as satellite QKD trials—and practical cryptographic infrastructure. The result suggests that high‑security sectors can begin to replace classical key‑exchange pipelines with quantum‑generated keys today, although scaling beyond tens of kilometres will still require advances in loss‑tolerant protocols or repeaters.
— Mark Eatherly
Summary
We demonstrate the feasibility of entanglement-based quantum key distribution (eQKD) in high-security financial infrastructure over a 22 km fiber link with 8 dB loss between two data centers using polarization entanglement. The fully automated system continuously generated secure keys for four months at an average rate of 63.8 kb/s, which were stored into a key management system and consumed to establish a VPN tunnel. The setup achieved 93.7% total up-time, with no downtime caused by the quantum optical components. Active polarization control kept the quantum bit error rate below 2% for 97.4% of the time and timing synchronization based on the entangled photon pairs' intrinsic temporal correlations achieved sub-300 ps precision. Our standalone system requires neither polarized guide lasers nor external high-precision time references. These results show practical integration of eQKD into operational financial infrastructure.