Light, matter, and quantum randomness generation: A relativistic quantum information perspective

We study how quantum randomness generation based on unbiased measurements on a hydrogen-like atom can get compromised by the unavoidable coupling of the atom with the electromagnetic field. We improve on previous literature by analyzing the light-atom interaction in 3+1 dimensions with no single-mode or rotating-wave approximations and taking into account the non-pointlike nature of the atom, its orbital structure, and the exchanges of angular momentum between atom and field. We show that preparing the atom in the ground state in the presence of no field excitations is not universally the safest state to generate randomness.