International Conference on Transparent Optical Networks
Multi-nodes quantum network in metropolitan area of Naples
Ciro Bruscino, M. Peluso, Pasquale Ercolano, C. Zhang, Daniela Salvoni, Angelo Giuliana, M. Venturini, Davide Bacco, Francesco B. L. Santagiustina, Tommaso Occhipinti, Luca Calderaro, Simone Capeleto, Alessandro Zavatta, Carlo Liorni, Giuseppe De Falco, Massimiliano Dispenza, G. Elia, R. Aiello, P. Maddaloni, G. Delli Santi, C. Perissinotto, Davide Calonico, L. Parlato, G. P. Pepe
Quantum Key Distribution (QKD) has been proven to be an unconditionally secure method for exchanging cryptographic keys under real-world conditions. By exploiting the principles of quantum physics, QKD enables the establishment of secret keys between two communicating parties, ensuring the security of transmitted data. Recently, numerous companies and research institutions have demonstrated the successful implementation of large-scale, high-speed communication systems in both laboratory settings and field tests. Additionally, several advanced network structures have been developed to facilitate secure communication via QKD, contributing to the creation of metropolitan-scale secure networks. In this work, we leverage the state-of-the-art of superconducting nanostrip single-photon detectors (SNSPDs) to enhance the performance of commercial QKD systems. These systems are deployed in a three-node network around the city of Naples, connecting an industrial hub with the Physics Department and the CNR-INO research center.The goal is to establish secure communication channels for exchanging and managing encrypted data. This work represents a significant step toward the practical realization of metropolitan-scale QKD networks and their integration into existing communication infrastructure. By using SNSPDs, we ensure high efficiency and low noise levels, contributing to more reliable and secure key distribution over metropolitan distances. The integration of these technologies demonstrates the feasibility of QKD as a cornerstone for future secure communications in urban environments.
Quantum Key Distribution (QKD) has been proven to be an unconditionally secure method for exchanging cryptographic keys under real-world conditions. By exploiting the principles of quantum physics, QKD enables the establishment of secret keys between two communicating parties, ensuring the security of transmitted data. Recently, numerous companies and research institutions have demonstrated the successful implementation of large-scale, high-speed communication systems in both laboratory settings and field tests. Additionally, several advanced network structures have been developed to facilitate secure communication via QKD, contributing to the creation of metropolitan-scale secure networks. In this work, we leverage the state-of-the-art of superconducting nanostrip single-photon detectors (SNSPDs) to enhance the performance of commercial QKD systems. These systems are deployed in a three-node network around the city of Naples, connecting an industrial hub with the Physics Department and the CNR-INO research center.The goal is to establish secure communication channels for exchanging and managing encrypted data. This work represents a significant step toward the practical realization of metropolitan-scale QKD networks and their integration into existing communication infrastructure. By using SNSPDs, we ensure high efficiency and low noise levels, contributing to more reliable and secure key distribution over metropolitan distances. The integration of these technologies demonstrates the feasibility of QKD as a cornerstone for future secure communications in urban environments.
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.
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.
The increasing reliance on optical communication networks for high-speed data transmission has amplified concerns regarding secure information exchange in the era of quantum computing. Classical cryptographic protocols such as RSA and ECC, though widely deployed, are vulnerable to attacks from large-scale quantum computers executing Shor’s algorithm. Quantum Key Distribution (QKD) has emerged as a revolutionary cryptographic paradigm that leverages the principles of quantum mechanics to enable theoretically unbreakable key exchange. This paper investigates the integration of QKD into optical communication networks, focusing on protocol design, implementation challenges, and potential scalability. Through scenario-based evaluation, the study highlights the trade-offs between quantum security and practical deployment constraints such as channel loss, photon detector efficiency, and key generation rates. Results from simulated models demonstrate that while QKD can achieve provable security in metropolitan-area networks, long-distance transmission requires advanced techniques such as quantum repeaters and trusted nodes. This work concludes that QKD offers a promising pathway toward quantum-safe communication but necessitates
Abstract Quantum key distribution (QKD) enables secure key exchanges between two remote users. The ultimate goal of secure communication is to establish a global quantum network. The existing field tests suggest that quantum networks are feasible. To achieve a practical quantum network, we need to overcome several challenges including realizing versatile topologies for large scales, simple network maintenance, extendable configuration and robustness to node failures. To this end, we present a field operation of a quantum metropolitan-area network with 46 nodes and show that all these challenges can be overcome with cutting-edge quantum technologies. In particular, we realize different topological structures and continuously run the network for 31 months, by employing standard equipment for network maintenance with an extendable configuration. We realize QKD pairing and key management with a sophisticated key control centre. In this implementation, the final keys have been used for secure communication such as real-time voice telephone, text messaging and file transmission with one-time pad encryption, which can support 11 pairs of users to make audio calls simultaneously. Combined with intercity quantum backbone and ground–satellite links, our metropolitan implementation paves the way toward a global quantum network.
In a society based on the continuous exchange of sensitive data and information, the importance of secure and trustful communications is essential. Quantum key distribution (QKD) makes it possible to share data in an unconditionally secure way exploiting the basic principles of Quantum Mechanics [1]. During the last 30 years, many QKD protocols have been developed and tested, achieving long distance transmission [2] and secret key rates up to hundreds of Mbits per second [3]. However, this technology is still far from a large-scale deployment in existing fiber networks and telecom infrastructures, due to multiple factors: low secret-key rate, limited distance between users, lack of applications, high costs and high requirements in terms of low noise fiber links.
Information security faces unprecedented challenges in the digital age, particularly in the face of cyber threats and the emergence of quantum computing. This research examines QKD as a solution for secure communications in urban fiber networks. The study analyzes QKD protocols, including BB84 and Twin-Field QKD, implementing a 46-node metropolitan quantum network and key distribution over distances greater than 1002 kilometers. Various transmission media, such as multicore optical fibers and free-space communication, were evaluated, demonstrating high-capacity quantum communication with advanced noise mitigation techniques. The results reveal significant advances in quantum communication security, highlighting the potential of QKD to provide theoretically secure key distribution based on quantum mechanical principles. The research addresses challenges such as transmission loss, environmental disturbances, and network scalability, laying the groundwork for future implementations in metropolitan networks. This work contributes significantly to the standardization of evaluation protocols and metrics, which is crucial for the global adoption of QKD in a world increasingly dependent on cybersecurity, especially in developing smart cities.