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Updated: Aug 23, 2026

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Decoy-State Quantum Key Distribution over 227 km with a Frequency-Converted Telecom Single-Photon Source
Frederik Brooke Barnes1, Roberto G Pousa2, Christopher L Morrison1
1Heriot-Watt University, Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Edinburgh EH14 4AS, United Kingdom.
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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 nondecoy schemes. This Letter broadens the scope of single-photon sources in future quantum networks by enabling long-distance quantum key distribution with realistic levels of single-photon purity.
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