Quantum key distribution using deterministic single-photon sources over a field-installed fibre link

Mujtaba Zahidy, Mikkel T. Mikkelsen, Ronny Müller, Beatrice Da Lio, Martin Krehbiel, Ying Wang, Nikolai Bart, Andreas D. Wieck, Arne Ludwig, Michael Galili, Søren Forchhammer, Peter Lodahl, Leif K. Oxenløwe, Davide Bacco*, Leonardo Midolo*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Quantum-dot-based single-photon sources are key assets for quantum information technology, supplying on-demand scalable quantum resources for computing and communication. However, long-lasting issues such as limited long-term stability and source brightness have traditionally impeded their adoption in real-world applications. Here, we realize a quantum key distribution field trial using true single photons across an 18-km-long dark fibre, located in the Copenhagen metropolitan area, using an optimized, state-of-the-art, quantum-dot single-photon source frequency-converted to the telecom wavelength. A secret key generation rate of > 2 kbits/s realized over a 9.6 dB channel loss is achieved with a polarization-encoded BB84 scheme, showing remarkable stability for more than 24 hours of continuous operation. Our results highlight the maturity of deterministic single-photon source technology while paving the way for advanced single-photon-based communication protocols, including fully device-independent quantum key distribution, towards the goal of a quantum internet.

Original languageEnglish
Article number2
Journalnpj Quantum Information
Issue number1
Number of pages6
Publication statusPublished - Dec 2024


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