Toshiba Europe Limited (Toshiba) and Quantum Bridge Technologies Inc. (QBT) have finalized a live network demonstration establishing an international, information-theoretic secure (ITS) data transmission system. Unveiled at the Optical Fiber Communication Conference (OFC) 2026, the cross-continental deployment connected operational metropolitan Quantum Key Distribution (QKD) networks in Cambridge, UK, and Toronto, Canada. The physical implementation was executed on field-installed carrier-grade fiber infrastructure hosted within data centers operated by Telehouse Canada Inc., a subsidiary of KDDI Corporation. The project validates an architecture designed to mitigate the distance limitations of standard fiber-based QKD by bypassing the absolute requirement for ultra-long-distance quantum repeaters or satellite linkages.
Technical Architecture & Specifications / Operational Implementation
The network topology integrates high-speed metropolitan QKD links with QBT’s Distributed Symmetric Key Establishment (DSKE) protocol to facilitate long-haul key relays. The Cambridge network utilized two fiber links operating under a 10 dB fixed attenuation profile, yielding secure bit rates (SBR) of 352 kbps and 741 kbps with corresponding quantum bit error rates (QBER) of 3.0% and 2.4%. The Toronto metropolitan network ran two links in a back-to-back hardware configuration (0 dB channel loss), stabilizing at average SBRs of 3.95 Mbps and 2.89 Mbps with QBERs of 2.6% and 3.2%. All hardware endpoints executed the T12 optimized efficient BB84 QKD protocol. Interoperability between the discrete vendor platforms was achieved by extending draft version 0.5.1 of the European Telecommunications Standards Institute (ETSI) GS QKD 020 Interoperable Key Management Specification. This REST API framework managed non-blocking, asynchronous key handovers between the co-located QKD and DSKE Key Management Entities (KMEs) at the network’s designated gateway nodes, deploying a (2,2) threshold secret-sharing scheme using pre-shared random data over public internet channels.
Strategic Positioning & Ecosystem Integration
The combined QKD-DSKE framework isolates the end-user application layer from complex physical and key-routing topologies, delivering on-demand 256-bit symmetric keys via standard ETSI GS QKD 014 delivery interfaces. Under active evaluation conditions, the initiating KME exhibited an average encryption key delivery response latency of 365 milliseconds (± 81 ms standard deviation), which accounts for the multi-hop key relay and trans-Atlantic network propagation delays. Conversely, the responding decryption KME delivered keys to the target application with an average latency of 14 milliseconds (± 5 ms), utilizing pre-buffered synchronization mechanisms. The architectural methodology establishes a baseline for multi-vendor, globally scalable quantum-safe networking capable of operating within current enterprise data center parameters while protecting sensitive communications against future algorithmic or quantum-accelerated cryptanalysis.
You can review the official press announcement detailing the trans-Atlantic network demonstration here. For complete engineering parameters, data configurations, and architectural specifications, download the full OFC technical paper here.
May 20, 2026
