Overview
- The QuNET testnet, which transmitted quantum-encrypted data on 28 October 2026, joined smaller networks in Berlin, Thuringia and Bavaria for a practical multi‑site demonstration.
- The seven‑year QuNet‑Initiative was backed with €125 million from the federal research ministry and involved major institutes including Max‑Planck, Fraunhofer, DLR, FAU and TUM.
- QuNET uses quantum key distribution (QKD) to send single photons that let sender and receiver detect eavesdropping because measuring those photons changes their quantum state.
- Engineers bridged long distances by using trusted nodes that convert quantum keys into classical keys and re‑encrypt them, a practical choice that does not provide pure end‑to‑end quantum security.
- Researchers say the main technical limits are photon loss in conventional fiber over a few hundred kilometres and the lack of working quantum repeaters, which must be solved before full end‑to‑end quantum links are possible.