Although the generation of true random numbers is crucial in modern digital electronic information systems for statistical sampling, cryptography, and other applications, the ability to generate these random numbers truly unpredictably and irreproducibly is limited in current common generation schemes such as extraction of a random bit from the random time intervals between the emission of photons from semiconductors. In these and other complex schemes, timing precision is a limitation to the random bit generation rate.
Researchers at Peking University (Beijing, China) have overcome this limitation with the development of a simple and compact method for true random-number generation based on photon-number detection of a weak laser pulse.
With equal probabilities for the bits of ones and zeroes, bias-free from the variabilities of the device and the environment, capable of generating random numbers at high speed, and only limited by the repetition rate of the single-photon detector used in the setup, the new technique essentially consists of an attenuated output from a pulsed distributed-feedback diode laser (300 ps pulses at 1550 nm) that is detected by an indium gallium arsenide photodetector operating in Geiger mode. A von Neumann correction method (with no post-processing required) is used for the detection scheme, which looks at the random bits generated from successive pairs of photon detections. Contact Hong Guo at hongguo@pku.edu.cn.