%0 Journal Article %J Nat. Phys. %D 2021 %T Device-independent Randomness Expansion with Entangled Photons %A Lynden K. Shalm %A Yanbao Zhang %A Joshua C. Bienfang %A Collin Schlager %A Martin J. Stevens %A Michael D. Mazurek %A Carlos Abellán %A Waldimar Amaya %A Morgan W. Mitchell %A Mohammad A. Alhejji %A Honghao Fu %A Joel Ornstein %A Richard P. Mirin %A Sae Woo Nam %A Emanuel Knill %X

With the growing availability of experimental loophole-free Bell tests, it has become possible to implement a new class of device-independent random number generators whose output can be certified to be uniformly random without requiring a detailed model of the quantum devices used. However, all of these experiments require many input bits in order to certify a small number of output bits, and it is an outstanding challenge to develop a system that generates more randomness than is used. Here, we devise a device-independent spot-checking protocol which uses only uniform bits as input. Implemented with a photonic loophole-free Bell test, we can produce 24% more certified output bits (1,181,264,237) than consumed input bits (953,301,640), which is 5 orders of magnitude more efficient than our previous work [arXiv:1812.07786]. The experiment ran for 91.0 hours, creating randomness at an average rate of 3606 bits/s with a soundness error bounded by 5.7×10−7 in the presence of classical side information. Our system will allow for greater trust in public sources of randomness, such as randomness beacons, and the protocols may one day enable high-quality sources of private randomness as the device footprint shrinks.

%B Nat. Phys. %8 01/28/2021 %G eng %U https://arxiv.org/abs/1912.11158 %R https://doi.org/10.1038/s41567-020-01153-4