Optical Post Processing for High Speed Quantum Random Number Generators

The speed of quantum random number generators is a major concern for practical quantum applications. However, the bit extraction process limits the final bit rate due to lack of comparably fast electronics. Here we introduce optical scattering as a method to perform optical bit extraction. Scattering is a probabilistic phenomenon and it increases the chaotic behaviour of coherent sources. As a result, it broadens the distribution of photon statistics and makes it super-Poissonian. We show that the raw signal of the sources with super-Poissonian distribution have better randomness compared to Poissonian, indicated by their autocorrelation characteristics. Therefore, the optical bit extraction process allows faster sampling of raw signal without compromising the randomness quality. The use of scattering mechanisms as an entropy source eases the miniaturization of quantum random number generators, it also makes them compatible and adaptable to existing technologies.