Quantum key distribution in the Iberian Peninsula

Journal Article (2026)
Author(s)

V. Dominguez Tubio (TU Delft - QID/Wehner Group)

M. Badas Aldecocea (TU Delft - Aerospace Engineering)

D.L. Bakker (TU Delft - BUS/TNO STAFF)

G. Castro do Amaral (TU Delft - BUS/TNO STAFF)

Diego López (Telefónica Research)

J. Borregaard (Harvard University)

Research Group
Space Systems Egineering
URL related publication
http://10.1364/OPTICAQ.581903
More Info
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Publication Year
2026
Language
English
Research Group
Space Systems Egineering
Journal title
Optica Quantum
Issue number
1
Volume number
4
Downloads counter
7
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Abstract

A promising use of quantum networking is quantum key distribution (QKD), which can provide information-theoretic security unattainable by classical means. While optical fiber-based QKD networks suffer from exponential loss, satellite-assisted quantum communication offers a scalable solution for long-distance secure key exchange. In this work, we propose and evaluate a satellite-based QKD setup covering the Iberian Peninsula, linking Madrid with Barcelona, Bilbao, and Lisbon. Our proposed setup uses a Low-Earth-Orbit (LEO) state-of-the-art satellite equipped with a spontaneous parametric down-conversion (SPDC) source to distribute entangled photon pairs to ground stations. Considering vibrations in the satellite, we optimize the beam waist to enhance the transmission probability and improve the secret key rate (SKR). Our results show that key rates sufficient for real-world applications, such as secure communication between hospitals, using hybrid classical-quantum protocols, are feasible with existing protocols. Our results highlight the viability of near-term satellite-based QKD networks for national-scale secure communications.