Quantum key distribution over a 40-dB channel loss using superconducting single-photon detectors

Hiroki Takesue, Sae Woo Nam, Qiang Zhang, Robert H. Hadfield, Toshimori Honjo, Kiyoshi Tamaki, Yoshihisa Yamamoto

Research output: Contribution to journalArticle

559 Citations (Scopus)

Abstract

We report the first quantum key distribution (QKD) experiment to enable the creation of secure keys over 42 dB channel loss and 200 km of optical fibre. We used the differential phase shift QKD (DPS-QKD) protocol, implemented with a 10-GHz clock frequency and superconducting single-photon detectors (SSPD) based on NbN nanowires. The SSPD offers a very low dark count rate (a few Hz) and small timing jitter (60 ps, full width at half maximum, FWHM). These characteristics allowed us to achieve a 12.1bit s-1 secure key rate over 200 km of fibre, which is the longest terrestrial QKD over a fibre link yet demonstrated. Moreover, this is the first 10-GHz clock QKD system to enable secure key generation. The keys generated in our experiment are secure against both general collective attacks on individual photons and a specific collective attack on multiphotons, known as a sequential unambiguous state discrimination (USD) attack. © Nature Publishing Group.

Original languageEnglish
Pages (from-to)343-348
Number of pages6
JournalNature Photonics
Volume1
Issue number6
DOIs
Publication statusPublished - Jun 2007

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    Takesue, H., Nam, S. W., Zhang, Q., Hadfield, R. H., Honjo, T., Tamaki, K., & Yamamoto, Y. (2007). Quantum key distribution over a 40-dB channel loss using superconducting single-photon detectors. Nature Photonics, 1(6), 343-348. https://doi.org/10.1038/nphoton.2007.75