Trnava Joins the Quantum Network: First skQCI Node Outside Bratislava Deployed
On April 9–10, the Slovak Quantum Communication Infrastructure (skQCI) project reached a next important milestone with the successful deployment of its first quantum communication node outside Bratislava — in Trnava. This step marks the transition from lab-based demonstrations to real-world deployment, as Slovakia moves toward building a national, quantum-secure network.
The newly launched node is hosted at the Faculty of Materials Science and Technology in Trnava, a valued academic partner that supports our shared vision of building a secure, quantum-based communication backbone across Slovakia. The installation was carried out by researchers from the Research Center for Quantum Information (RCQI) of Institute of Physics SAS — Djeylan Aktas (project lead), Gilberto Borges, Saeid Salari, Younes Benamara, and Peter Rapčan together with Andrej Buček from International Laser Center of SCSTI — in collaboration with suppliers from Quantum Industries (Mirela Selimovic, Thomas Heine, Sebastian Neumann).
Powered by Quantum Light and Precision Engineering
At the heart of the Trnava node is HERCULES — the High-Emission-Rate Quantum Light Entangled System developed by Quantum Industries. This rack-mounted platform generates entangled photons and transmits them through optical fibers, enabling entanglement-based QKD (eQKD) between network nodes. Capable of supporting simultaneous connections with up to six users (and scalable to sixteen), it’s a cornerstone of the evolving skQCI network. Complementing this setup is the ELVIS EKD-System from Quantum Optics Jena, featuring automatic polarization control and key management servers that ensure stable, secure transmission over time.
Precise Cryogenic Quantum Detection and Dynamic Switching for a Scalability
Photon detection is handled by superconducting nanowire single-photon detectors (SNSPDs) from Single Quantum. These ultra-sensitive detectors operate near 2 Kelvin and can achieve up to 90% detection efficiency. A complete cryogenic infrastructure — cryostat, vacuum pump, helium compressor, and a high-resolution timetagger — ensures precise time-correlation of photon arrivals, a crucial aspect of eQKD.
The installation also includes a POLATIS Series 6000 multimode optical switch, allowing for dynamic user connection management within the quantum network. With ultra-low optical loss and flexible software control, it is a key enabler for a scalable and responsive network.
Future Outlook
This node is the first of its kind deployed outside the capital and a critical component of Slovakia’s evolving quantum communication backbone. It provides a testing ground for secure key distribution, long-term system operation, and protocol validation under real-world conditions.
In the next stage of the skQCI rollout, the Trnava node will be connected with other locations as soon as we complete the procurement and installation of dedicated optical fiber links between cities — a technically demanding but essential step toward enabling secure, city-to-city quantum communication.
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