Generation of Fresh and Pure Random Numbers for Loophole-Free Bell Tests

Abstract

We demonstrate extraction of randomness from spontaneous-emission events less\nthan 36 ns in the past, giving output bits with excess predictability below\n$10^{-5}$ and strong metrological randomness assurances. This randomness\ngeneration strategy satisfies the stringent requirements for unpredictable\nbasis choices in current "loophole-free Bell tests" of local realism [Hensen et\nal., Nature (London) 526, 682 (2015); Giustina et al., Phys. Rev. Lett. 115,\n250401 (2015); Shalm et al., Phys. Rev. Lett. 115, 250402 (2015)].\n