Generation of correlated quantum random number sequences with bright twin beams

Abstract

Quantum random number generators play a vital role in securing communication and encryption. In the present work, we have produced bright twin beams using four-wave mixing in a double-Λ configuration in rubidium-85 vapor and generated two strings of highly correlated random numbers. The randomness originates from the probabilistic nature of the intensity fluctuations of the twin beams and the quantum correlations are certified by measuring the intensity-difference squeezing in the generated twin beams. At an analysis frequency of 2 MHz, we have measured 95% correlation between the random intensity fluctuations of the twin beams. We observe over 5 bits/sample of entropy from the quantum fluctuations of the twin beams. Furthermore, to extract identical strings of random numbers, post-selection of the binned data and hashing algorithms are used, leading to a binary string of random numbers at a rate of 6 Mbps that passes standard statistical tests from NIST and TestU01. Here, the simplicity of generating bright twin beams shows the potential of this method in quantum cryptography and quantum communication.