CL. Morrison, RG. Pousa, F. Graffitti, Z. Xian Koong, P. Barrow, N.G. Stoltz, D. Bouwmeester, J. Jeffers, DKL. Oi, BD. Gerardot, A. Fedrizzi.
Submitted to arXiv on 7 September 2022
Quantum key distribution with solid-state single-photon emitters is gaining traction due to their rapidly improving performance and compatibility with future quantum network architectures. In this work, we perform fibre-based quantum key distribution with a quantum dot frequency-converted to telecom wavelength, achieving count rates of 1.6 MHz with g(2)(0)=3.6%. We demonstrate positive key rates up to 175 km in the asymptotic regime. We then show that the community standard analysis for non-decoy state QKD drastically overestimates the acquisition time required to generate secure finite keys. Our improved analysis using the multiplicative Chernoff bound reduces the required number of received signals by a factor of 108 over existing work, with the finite key rate approaching the asymptotic limit at all achievable distances for acquisition times of one hour. Over a practical distance of 100 km we achieve a finite key rate of 13 kbps after one minute of integration time. This result represents major progress towards the feasibility of long-distance single-emitter QKD networks.