BIQuaN SASPRO2 1156/01/01

Title:Backbone of an International Quantum Network
Duration: 01/10/2022 - 30/09/2025
Principal Investigator: Dr. Djeylan Aktas
Mentor: Mário Ziman
Budget: 188 496 eur

Project Goals:Quantum communication is rapidly gaining popularity due to its high levels of security and technological maturity. Experimental devices have already been taken out of the lab and purpose-built Quantum Key Distribution systems are now an option for real-world communication thus ensuring provably secured point-to-point links. The history of quantum networks is already rich in attempts to stack these links in a telecommunication infrastructure and recently, hundreds of millions of euros of research funding have been allocated to build large-scale quantum communication network. However, most implementations suffer from drawbacks preventing them from being widely adopted. The first difficulty one encounters with a trusted-node approach is the resource overhead of a fully connected mesh, and second while trying to deploy these QKD systems, is their limited range of operation. They are quite efficient at a metropolitan scale but the drastic decreasing rate with losses and the nature of quantum information, disallowing amplification, make inter-city links a challenge. Entanglement-based QKD is key to build a scalable trusted-node free and fully connected quantum network. Amongst those protocols, Flood Light QKD is a prime candidate to solve bottleneck issues in connecting clusters of metropolitan networks with a single link. This protocol is not constrained by the fundamental limits of repeaterless quantum communications like standard QKD schemes and can reach gigabits rates of unconditionally secure communication. The challenge resting on the fact that it employs a phase-stable interferometric system deployed over a long optical fibre. This project aims at combining various QKD protocols for establishing full connectivity of multiple nodes over short distances and some specific entanglement-based protocols for reaching long distance of quantum communication. Hence, creating the backbone of a first international quantum communication network.

Researchers: Djeylan Aktas