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

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).