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Towards a European quantum network

Domenico Ribezzo, Mujtaba Zahidy, Ilaria Vagniluca, Nicola Biagi, Saverio Francesconi, Tommaso Occhipinti, Leif Katsuo Oxenløwe, Martin Lončarić, Ivan Cvitić, Mario Stipčević, Žiga Pušavec, Rainer Kaltenbaek, A. Ramšak, Franceso Cesa, Giorgetti, G, Francesco Scazza, Angelo Bassi, Paolo De Natale, Saverio Francesconi, M. Inguscio, Davide Bacco, Alessandro Zavatta

Published Jan 1, 2022• 3 citations
OpenAlex

Abstract

Already deployed optical fibers have been utilized to realize the first quantum network connecting three countries. The cities of Trieste (Italy), Rijeka (Croatia) and Ljubljana (Slovenia) have exchanged quantum keys with a rate up to 3.13 kps, realizing quantum key distribution in a real-world scenario.

Related papers

Towards a European quantum network

Domenico Ribezzo, Mujtaba Zahidy, Ilaria Vagniluca +19 more

Already deployed optical fibers have been utilized to realize the first quantum network connecting three countries. The cities of Trieste (Italy), Rijeka (Croatia) and Ljubljana (Slovenia) have exchanged quantum keys with a rate up to 3.13 kps, realizing quantum key distribution in a real-world scenario.

•Jan 1, 2022•0 citations

Building the Practical Foundations of a European Quantum Communication Infrastructure

Domenico Ribezzo, Mujtaba Zahidy, Claudia De Lazzari +7 more

Today, quantum networks have made Quantum Key Distribution (QKD) the standard method for securely distributing encryption keys among multiple parties. In this study, we present an approach to implementing quantum networks, validated through on-field implementations. Utilizing a weak coherent pulse source, an optimized BB84 protocol (efficient BB84), and optical fiber channels, we took the initial steps within the European Quantum Communication Infrastructure (EuroQCI) initiative. Our method successfully established a quantum network linking the cities of Trieste (Italy), Rijeka (Croatia), and Ljubljana (Slovenia)-the first to connect three different countries. A second quantum link between Malta and Sicily (Italy) was established for technological characterization, while a multi-core optical fiber in downtown L’Aquila (Italy) facilitated the first QKD process involving high-dimensional quantum states in a real-world scenario.

International Conference on Transparent Optical Networks•Jul 14, 2024•0 citations

Deploying an Inter‐European Quantum Network

Domenico Ribezzo, Mujtaba Zahidy, Ilaria Vagniluca +19 more

Abstract Around 40 years have passed since the first pioneering works introduced the possibility of using quantum physics to enhance communications safety. Nowadays, quantum key distribution (QKD) exited the physics laboratories to become a mature technology, triggering the attention of States, military forces, banks, and private corporations. This work takes on the challenge of bringing QKD closer to a consumer technology: deployed optical fibers by telecommunication companies of different States have been used to realize a quantum network, the first‐ever connecting three different countries. This work also emphasizes the necessity of networks where QKD can come up besides classical communications, whose coexistence currently represents the main limitation of this technology. This network connects Trieste to Rijeka and Ljubljana via a trusted node in Postojna. A key rate of over 3 kbps in the shortest link and a 7‐hour‐long measurement demonstrate the system's stability and reliability. The network has been used to present the QKD at the G20 Digital Ministers' Meeting in Trieste. The experimental results, together with the interest that one of the most important events of international politics has attracted, showcase the maturity of the QKD technology bundle, placing it in the spotlight for consumer applications in the near term.

arXiv:2203.11359•Advanced Quantum Technologies•Dec 14, 2022•102 citations

Advancements in deployed quantum communication networks

Domenico Ribezzo, Carlo Marconi, Luca Bianchi +6 more

Quantum communication has established itself as a reliable and effective method of ensuring absolute confidentiality by exploiting quantum properties. We reached a significant milestone with the launch of the first quantum network connecting three European countries during the G20 meeting in Trieste. A reliable quantum key distribution (QKD) link using an undersea fibre-optic cable between the islands of Malta and Sicily was successfully implemented using an innovative room-temperature single-photon detector that outperformed standard detectors. We also implemented QKD in two terrestrial free-space links in the Florence area, demonstrating that time-bin, fibre-based QKD systems can be efficiently used for free-space communications links.

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A quantum key distribution network in the metropolitan area of Padova

Marco Avesani, Giulio Foletto, Matteo Padovan +13 more

One of the most advanced technologies within the field of quantum mechanics is quantum key distribution (QKD), which allows the secure generation of secret keys among remote users. In order for QKD to be more widely adopted, it must be integrated into existing classical communication systems. However, this can be difficult due to the use of various technologies and channels in deployed networks. Recently, we developed a QKD network in the metropolitan area of Padova, which connects various nodes across the city through a combination of fiber and free-space links. By utilizing a modular design based on the iPOGNAC encoder and the Qubit4Sync method, we have realized portable and adaptable systems that operate in the C and O bands. This allowed us to deploy and test the compatibility of both research and commercial QKD systems by ThinkQuantum with classical communication over a variety of links, as well as their ability to switch between free-space and fiber connections. Finally, we developed and experimentally implemented complex network configurations such as star networks, where a fiber-based transmitter and free-space transmitter could operate with a single receiver.

Quantum Computing, Communication, and Simulation•Mar 8, 2023•4 citations

Multi-node quantum key distribution network using existing underground optical fibre infrastructure

Mariella Minder, Andreas Siakolas, Stephanos Yerolatsitis +2 more

Quantum key distribution (QKD) offers unconditional information security by allowing two distant users to establish a common encryption key resilient to hacking. Resultingly, QKD networks interconnecting critical infrastructure and enabling the secure exchange of classified information, can provide a solution to the increasing number of successful cyberattacks. To efficiently deploy quantum networks, the technology must be integrated over existing communication infrastructure, such as optical fibre links. Yet, QKD poses stringent requirements on the conditions of the network over which it is deployed. This work demonstrates the first quantum communication network in Cyprus via the deployment of a multi-node quantum network, exploiting existing commercial underground optical fibre. The network employs bidirectional occupation of fibres and wavelength multiplexing in a ring architecture to achieve, with minimal use of dark fibres, high-rate QKD. Results obtained reveal consistent key generation rates across all nodes, confirming reliable operation in a real-world environment. This deployment highlights the feasibility of leveraging existing telecom infrastructure for quantum-secured communication, marking a significant step toward scalable and cost-effective quantum networks suited for critical applications.

quant-pharXiv:2512.02701•Workshop on Specialty Optical Fibers and Their Applications (WSOF)•Dec 3, 2025•0 citations
Today, quantum networks have made Quantum Key Distribution (QKD) the standard method for securely distributing encryption keys among multiple parties. In this study, we present an approach to implementing quantum networks, validated through on-field implementations. Utilizing a weak coherent pulse source, an optimized BB84 protocol (efficient BB84), and optical fiber channels, we took the initial steps within the European Quantum Communication Infrastructure (EuroQCI) initiative. Our method successfully established a quantum network linking the cities of Trieste (Italy), Rijeka (Croatia), and Ljubljana (Slovenia)-the first to connect three different countries. A second quantum link between Malta and Sicily (Italy) was established for technological characterization, while a multi-core optical fiber in downtown L’Aquila (Italy) facilitated the first QKD process involving high-dimensional quantum states in a real-world scenario.
Abstract Around 40 years have passed since the first pioneering works introduced the possibility of using quantum physics to enhance communications safety. Nowadays, quantum key distribution (QKD) exited the physics laboratories to become a mature technology, triggering the attention of States, military forces, banks, and private corporations. This work takes on the challenge of bringing QKD closer to a consumer technology: deployed optical fibers by telecommunication companies of different States have been used to realize a quantum network, the first‐ever connecting three different countries. This work also emphasizes the necessity of networks where QKD can come up besides classical communications, whose coexistence currently represents the main limitation of this technology. This network connects Trieste to Rijeka and Ljubljana via a trusted node in Postojna. A key rate of over 3 kbps in the shortest link and a 7‐hour‐long measurement demonstrate the system's stability and reliability. The network has been used to present the QKD at the G20 Digital Ministers' Meeting in Trieste. The experimental results, together with the interest that one of the most important events of international politics has attracted, showcase the maturity of the QKD technology bundle, placing it in the spotlight for consumer applications in the near term.
Quantum communication has established itself as a reliable and effective method of ensuring absolute confidentiality by exploiting quantum properties. We reached a significant milestone with the launch of the first quantum network connecting three European countries during the G20 meeting in Trieste. A reliable quantum key distribution (QKD) link using an undersea fibre-optic cable between the islands of Malta and Sicily was successfully implemented using an innovative room-temperature single-photon detector that outperformed standard detectors. We also implemented QKD in two terrestrial free-space links in the Florence area, demonstrating that time-bin, fibre-based QKD systems can be efficiently used for free-space communications links.
One of the most advanced technologies within the field of quantum mechanics is quantum key distribution (QKD), which allows the secure generation of secret keys among remote users. In order for QKD to be more widely adopted, it must be integrated into existing classical communication systems. However, this can be difficult due to the use of various technologies and channels in deployed networks. Recently, we developed a QKD network in the metropolitan area of Padova, which connects various nodes across the city through a combination of fiber and free-space links. By utilizing a modular design based on the iPOGNAC encoder and the Qubit4Sync method, we have realized portable and adaptable systems that operate in the C and O bands. This allowed us to deploy and test the compatibility of both research and commercial QKD systems by ThinkQuantum with classical communication over a variety of links, as well as their ability to switch between free-space and fiber connections. Finally, we developed and experimentally implemented complex network configurations such as star networks, where a fiber-based transmitter and free-space transmitter could operate with a single receiver.
Quantum key distribution (QKD) offers unconditional information security by allowing two distant users to establish a common encryption key resilient to hacking. Resultingly, QKD networks interconnecting critical infrastructure and enabling the secure exchange of classified information, can provide a solution to the increasing number of successful cyberattacks. To efficiently deploy quantum networks, the technology must be integrated over existing communication infrastructure, such as optical fibre links. Yet, QKD poses stringent requirements on the conditions of the network over which it is deployed. This work demonstrates the first quantum communication network in Cyprus via the deployment of a multi-node quantum network, exploiting existing commercial underground optical fibre. The network employs bidirectional occupation of fibres and wavelength multiplexing in a ring architecture to achieve, with minimal use of dark fibres, high-rate QKD. Results obtained reveal consistent key generation rates across all nodes, confirming reliable operation in a real-world environment. This deployment highlights the feasibility of leveraging existing telecom infrastructure for quantum-secured communication, marking a significant step toward scalable and cost-effective quantum networks suited for critical applications.