Single-emitter quantum key distribution over 175 km of fibre with optimised finite key rates

Christopher L. Morrison, Roberto G. Pousa, Francesco Graffitti, Zhe Xian Koong, Peter Barrow, Nick G. Stoltz, Dirk Bouwmeester, John Jeffers, Daniel K. L. Oi, Brian D. Gerardot, Alessandro Fedrizzi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)
17 Downloads (Pure)


Quantum key distribution with solid-state single-photon emitters is gaining traction due to their rapidly improving performance and compatibility with future quantum networks. Here we emulate a quantum key distribution scheme with quantum-dot-generated single photons frequency-converted to 1550 nm, achieving count rates of 1.6 MHz with g(2) (0)=3.6% and asymptotic positive key rates over 175 km of telecom fibre. We show that the commonly used finite-key analysis for non-decoy state QKD drastically overestimates secure key acquisition times due to overly loose bounds on statistical fluctuations. Using the tighter multiplicative Chernoff bound to constrain the estimated finite key parameters, we reduce the required number of received signals by a factor 108. The resulting finite key rate approaches the asymptotic limit at all achievable distances in acquisition times of one hour, and at 100 km we generate finite keys at 13 kbps for one minute of acquisition. This result is an important step towards long-distance single-emitter quantum networking.
Original languageEnglish
Article number3573
JournalNature Communications
Publication statusPublished - 16 Jun 2023


  • Photons
  • Plant Structures
  • Quantum Dots
  • Traction

ASJC Scopus subject areas

  • General Physics and Astronomy
  • General Chemistry
  • General Biochemistry,Genetics and Molecular Biology


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