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

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

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 12.1 bit 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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hadfield, Professor Robert
• Authors: Takesue, H., Nam, S.W., Zhang, Q., Hadfield, R.H., Honjo, T., Tamaki, K., and Yamamoto, Y.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Nature Photonics
• ISSN: 1749-4885
• Published Online: 01 June 2007