On August 5, 2021, the first public demonstration of intergovernmental quantum communication between three countries took place during the G20 Digital Ministers’ Meeting in Trieste, Italy. Encrypted audio-video communication was established between nodes in Trieste, Ljubljana, and Rijeka using quantum key distribution (QKD), as reported by the EU Quantum Flagship.
For Slovenia, Prof. Rainer Kaltenbaek and Prof. Anton Ramšak from the Faculty of Mathematics and Physics at the University of Ljubljana led the effort, with technical support from Telekom Slovenije, which provided fibre-optic infrastructure via dark fibres through Postojna. On the Italian side, the demonstration was organized by the University of Trieste and the National Institute of Optics (CNR-INO). Croatian participation was coordinated by the Ruđer Bošković Institute.
Tommaso Calarco, President of the European Quantum Community Network, described the demonstration as “laying the foundation stone” of a new European quantum infrastructure. The event was carried out in the context of the EuroQCI initiative and represented the first quantum transmission between three nodes situated at distances of 50 and 80 kilometers.