Random bit generation using coherent state and threshold detectors at 1550 nanometers.

Abstract

We theoretically propose and experimentally validate a practical random bit generation method based on the detections of a coherent state in the few-photon regime by a gated single-photon threshold detector, operating at the telecom wavelength of 1550 nanometers. By fine tuning the mean number of photons per pulse of a laser beam directed to the single-photon detector, a 50-50 chance of detection or no-detection is reached; under this condition, detections inside the gate window are treated as "1"s, while "0"s are associated with the absence of detections. The same method could also be applied in a free-running single-photon detector for increased throughput by chopping the light signal instead of gating the detector. Both hardware implementations yielded bit strings, which were evaluated by a standard randomness test suite with good confidence. Despite the yet low rates achieved by the proposed method, its hardware compatibility with quantum key distribution setups makes it an interesting candidate for random number generation within the context of practical quantum communications.