open access publication

Article, 2024

Long-distance continuous-variable quantum key distribution over 100-km fiber with local local oscillator

Science Advances, ISSN 2375-2548, Volume 10, 1, Page eadi9474, 10.1126/sciadv.adi9474

Contributors

Hajomer, Adnan A E (Corresponding author) [1] Derkach, Ivan D 0000-0001-8014-7202 [1] [2] Jain, Nitin 0000-0001-8555-1773 [1] Chin, Hou-Man 0000-0002-2488-9305 [1] Andersen, Ulrik Lund 0000-0002-1990-7687 [1] Gehring, Tobias 0000-0002-4311-2593 (Corresponding author) [1]

Affiliations

  1. [1] Technical University of Denmark
    2. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD];
  2. [2] Palacký University, Olomouc
    3. [NORA names: Czechia; Europe, EU; OECD]

Abstract

Quantum key distribution (QKD) enables two remote parties to share encryption keys with security based on the laws of physics. Continuous-variable (CV) QKD with coherent states and coherent detection integrates well with existing telecommunication networks. Thus far, long-distance CV-QKD has only been demonstrated using a highly complex scheme where the local oscillator is transmitted, opening security loopholes for eavesdroppers and limiting potential applications. Here, we report a long-distance CV-QKD experiment with a locally generated local oscillator over a 100-kilometer fiber channel with a total loss of 15.4 decibels. This record-breaking distance is achieved by controlling the phase noise-induced excess noise through a machine learning framework for carrier recovery and optimizing the modulation variance. We implement the full CV-QKD protocol and demonstrate the generation of keys secure against collective attacks in the finite-size regime. Our results mark a substantial milestone for realizing CV quantum access networks with a high loss budget and pave the way for large-scale deployment of secure QKD.

Keywords

CV-QKD, CV-QKD protocol, access networks, applications, attacks, budget, carrier recovery, carriers, channel, coherent detection, coherent states, continuous-variable (CV, continuous-variable quantum key distribution, decibels, detection, distance, distribution, eavesdropper, encryption, encryption key, excess noise, experiments, fiber channel, fibers, finite-size regime, framework, generation, generation of keys, key distribution, keys, large-scale deployment, law, laws of physics, learning framework, local local oscillator, local oscillator, loopholes, loss, loss budget, machine, machine learning framework, modulation, modulation variance, network, noise, oscillations, parties, phase, physics, potential applications, protocol, quantum, quantum access network, quantum key distribution, recovery, regime, remote parties, results, secure quantum key distribution, security, security loopholes, state, telecommunication networks, telecommunications, variance

Funders

  • Danish National Research Foundation
  • Carlsberg Foundation
  • Innovation Fund Denmark
  • Czech Science Foundation
  • European Commission

Data Provider: Digital Science

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