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

7 Citations (Scopus)
12 Downloads (Pure)

Abstract

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 g20=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
Volume14
Issue number1
DOIs
Publication statusPublished - 16 Jun 2023

Keywords

  • quantum information
  • single photons and quantum effects
  • quantum networks
  • quantum key distribution (QKD)
  • optical fibre
  • finite key treatment

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