Applied Physics Letters

Time-division single-photon Sagnac interferometer for quantum key distribution

Chunyuan Zhou, Heping Zeng

Published Jan 30, 2003• 18 citations

Abstract

We introduce a single-photon Sagnac interferometer for quantum cryptography using time-division phase modulation. The interferometer was arranged to allow coherent laser pulses to travel clockwise and counter-clockwise along the same fiber loop with the corresponding phases modulated in separated periods, interfering at the exit coupler. High visibility of the single-photon interference was observed over a long-distance Sagnac loop. Stable performance was realized by passive compensation of stress and temperature-dependent drifts of the fiber-optic path. Time-division phase encoding and decoding can be realized by controlling the applied electric pulses on integrated phase modulators in the Sagnac loop, which makes this system suitable for a practical quantum cryptography system.

DOI: 10.1063/1.1541102

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