John von Neumann once said “Anyone who attempts to generate random numbers by deterministic means is, of course, living in a state of sin.” Enter Calvin Leung from Harvey Mudd College in California and colleagues. In earlier work, Leung and co-workers used light coming from stars in the Milky Way to develop a random-number generator to assign detector settings for a so-called Bell experiment, which tests the quantum nature of a system. This allowed them to rule out any local correlations between the particles and detectors used in the experiment going back 600 years into the past. The team has now used (distant) quasars to push this time frame back to near the beginning of the universe.

Further reading

C Leung et al. 2018 Phys. Rev. A 97 042120.