Los Alamos Researchers Enable Quantum Key Distribution Over 50km Fiber

A team of Los Alamos National Laboratory scientists, in collaboration with researchers from the National Institute of Standards and Technology in Boulder, Colo., and Albion College, in Albion, Mich., have achieved quantum key distribution (QKD) at telecommunications industry wavelengths in a 50-kilometer (31 mile) optical fiber. According to the researchers, the work could accelerate the development of QKD for secure communications in optical fibers at distances far beyond current technological limits.

In research published recently in Applied Physics Letters, the team describes the use of new superconducting transition-edge sensors (TES) to distribute cryptographic key material at wavelengths of 1,550 nanometers through 50 kilometers of optical fiber. TES could provide increases in range and performance over current QKD photon detection schemes. Unlike the single-photon sensitive avalanche photodiodes (APD) that are typically used in existing optical fiber QKD systems, TESs detect photons by measuring minute temperature increases in a superconducting material caused by the absorption of individual photons.

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