Article in EPJ Quantum Technology 

Matija Koterle, Jure Pirman, Tadej Mežnaršič, Katja Gosar, Erik Zupanič and Peter Jeglič from the Department of Condensed Matter Physics F5 and colleagues form the Department of Theoretical Physics F1 and Faculty of Electrical Engineering have published a paper in EPJ Quantum Technology with the tittle Mbit/s-range alkali vapour spin noise quantum random number generators.

Spin noise based quantum random number generators first appeared in 2008 and have since then garnered little further interest, in part because their bit rate is limited by the transverse relaxation time which is typically in the kbit/s range for coated alkali vapour cells. In the paper the researchers present two advances to spin noise based quantum random number generators. The first is an improved bit generation protocol that allows generating bits at high rates with only a minor increase of serial correlations. The second is a significant reduction of the transverse relaxation time itself by removing the coating, increasing the vapour temperature, and introducing a magnetic-field gradient. In this way they managed to increase the bit generation rate to 1.04 Mbit/s. They analysed the quality of the generated random bits using entropy estimation and they discuss the extraction methods to obtain high-entropy bitstreams. We accurately predict the entropy output of the device backed with a stochastic model and numerical simulations.