Quantum B Secures European Patent for Quantum Conference Key Agreement Protocol

Quantum cryptography and security developer Quantum B, Inc. (formerly Quantum Blockchains) has been granted European Patent EP 4462727 (Application EP23461579) by the European Patent Office (EPO). The patent covers a Quantum Conference Key Agreement (QCKA) protocol designed to establish distributed consensus across independent network nodes using multipartite quantum entanglement, providing an alternative to classical consensus mechanisms like proof-of-work or voting algorithms.

The patented architecture utilizes a central quantum server that emits time-bin encoded photons transformed into multi-qubit Greenberger-Horne-Zeilinger (GHZ) states. Participating network nodes receive qubit measurement outcomes over quantum links while coordinating over classical Internet channels. By executing local measurements on distributed GHZ states, nodes derive correlated bit values to verify and execute operations on shared data blocks when locally calculated values achieve majority consensus across the network.

Under CEO Mirek Sopek and co-inventor Miriam Kosik, the Łódź and Lublin-based company developed the protocol to lower the communication overhead required for classical multi-party synchronization. The patent milestone supports Quantum B's broader hardware and software portfolio—which includes its emulated Quantum Key Distribution (pQKD) hardware platform—and its ongoing participation in the EU-funded POSEIDON project focused on post-quantum digital identity protection.

Review the official news release via Quantum B Documentation here and inspect patent application documentation at the European Patent Office Register here.

September 18, 2026