We demonstrate extraction of randomness from spontaneous-emission events less than 36 ns in the past, giving output bits with excess predictability below 10−5 and strong metrological randomness assurances. This randomness generation strategy satisfies the stringent requirements for unpredictable basis choices in current "loophole-free Bell tests" of local realism [Hensen et al., Nature (London) 526, 682 (2015); Giustina et al., Phys. Rev. Lett. 115, 250401 (2015); Shalm et al., Phys. Rev. Lett. 115, 250402 (2015)].
@article{arxiv.1506.02712,
title = {Generation of fresh and pure random numbers for loophole-free Bell tests},
author = {Carlos Abellan and Waldimar Amaya and Daniel Mitrani and Valerio Pruneri and Morgan W. Mitchell},
journal= {arXiv preprint arXiv:1506.02712},
year = {2015}
}