Decoy-state quantum key distribution over 227 km with a frequency-converted telecom single-photon source

Frederick Barnes; Roberto G. Pousa; Christopher L. Morrison; Zhe Xian Koong; Joseph Ho; Francesco Graffitti; John Jeffers; Daniel K. L. Oi; Brian D. Gerardot; Alessandro Fedrizzi

doi:10.48550/arXiv.2512.05101

Decoy-state quantum key distribution over 227 km with a frequency-converted telecom single-photon source

Frederick Barnes, Roberto G. Pousa, Christopher L. Morrison, Zhe Xian Koong, Joseph Ho, Francesco Graffitti, John Jeffers, Daniel K. L. Oi, Brian D. Gerardot, Alessandro Fedrizzi

Research output: Working paper › Working Paper/Preprint

Abstract

We implement a decoy-state quantum key distribution scheme using a telecom C-band single- emitter source. The decoy states are created by varying the optical excitation of the quantum emitter to modulate the photon number distribution. We provide an analysis of our scheme based on existing security proofs, allowing the calculation of secret key rates including finite key effects. This enables us to demonstrate, with a realistic single-photon source, positive secret key rates using our scheme over 227 km of optical fiber, equivalent to a loss tolerance one order of magnitude greater than non-decoy schemes. This work broadens the scope of single-photon sources in future quantum networks by enabling long-distance QKD with realistic levels of single-photon purity.

Original language	English
Number of pages	9
DOIs	https://doi.org/10.48550/arXiv.2512.05101
Publication status	Published - 4 Dec 2025

Funding

This work was supported by the EPSRC Quantum Technology Hub in Quantum Communication (EP/T001011/1), International Network in Space Quantum Technologies (EP/W027011/1), and the Integrated Quantum Networks Research Hub (EP/Z533208/1). B.D.G. acknowledges support from the Royal Academy of Engineering for a Chair in Emerging Technology.

Keywords

quant-ph

Access to Document

10.48550/arXiv.2512.05101Licence: CC BY 4.0

Preprint-Barnes-etal-2025-Decoy-state-quantum-key-distribution-over-227-kmFinal published version, 1.04 MBLicence: CC BY 4.0

Doctoral Training Partnership 2018-19 University of Strathclyde | Gonzalez Pousa, Roberto
Oi, D. (Principal Investigator), Jeffers, J. (Co-investigator) & Gonzalez Pousa, R. (Research Co-investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/10/20 → 1/04/24
Project: Research Studentship - Internally Allocated
The EPSRC Quantum Communications Hub
Oi, D. (Principal Investigator) & Sidhu, J. (Researcher)
EPSRC (Engineering and Physical Sciences Research Council)
1/12/19 → 30/11/25
Project: Research

Cite this

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abstract = "We implement a decoy-state quantum key distribution scheme using a telecom C-band single- emitter source. The decoy states are created by varying the optical excitation of the quantum emitter to modulate the photon number distribution. We provide an analysis of our scheme based on existing security proofs, allowing the calculation of secret key rates including finite key effects. This enables us to demonstrate, with a realistic single-photon source, positive secret key rates using our scheme over 227 km of optical fiber, equivalent to a loss tolerance one order of magnitude greater than non-decoy schemes. This work broadens the scope of single-photon sources in future quantum networks by enabling long-distance QKD with realistic levels of single-photon purity.",

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AU - Ho, Joseph

AU - Graffitti, Francesco

AU - Jeffers, John

AU - Oi, Daniel K. L.

AU - Gerardot, Brian D.

AU - Fedrizzi, Alessandro

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N2 - We implement a decoy-state quantum key distribution scheme using a telecom C-band single- emitter source. The decoy states are created by varying the optical excitation of the quantum emitter to modulate the photon number distribution. We provide an analysis of our scheme based on existing security proofs, allowing the calculation of secret key rates including finite key effects. This enables us to demonstrate, with a realistic single-photon source, positive secret key rates using our scheme over 227 km of optical fiber, equivalent to a loss tolerance one order of magnitude greater than non-decoy schemes. This work broadens the scope of single-photon sources in future quantum networks by enabling long-distance QKD with realistic levels of single-photon purity.

AB - We implement a decoy-state quantum key distribution scheme using a telecom C-band single- emitter source. The decoy states are created by varying the optical excitation of the quantum emitter to modulate the photon number distribution. We provide an analysis of our scheme based on existing security proofs, allowing the calculation of secret key rates including finite key effects. This enables us to demonstrate, with a realistic single-photon source, positive secret key rates using our scheme over 227 km of optical fiber, equivalent to a loss tolerance one order of magnitude greater than non-decoy schemes. This work broadens the scope of single-photon sources in future quantum networks by enabling long-distance QKD with realistic levels of single-photon purity.

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ER -

Decoy-state quantum key distribution over 227 km with a frequency-converted telecom single-photon source

Abstract

Funding

Keywords

Access to Document

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Projects

Doctoral Training Partnership 2018-19 University of Strathclyde | Gonzalez Pousa, Roberto

The EPSRC Quantum Communications Hub

Cite this