Certified randomness from a two-level system in a relativistic quantum field
Thinh Lê (TU Delft - QuTech Advanced Research Centre, TU Delft - QID/Wehner Group, National University of Singapore)
Jean Daniel Bancal (National University of Singapore)
Eduardo Martín-Martínez (University of Waterloo, Perimeter Institute for Theoretical Physics)
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Abstract
Randomness is an indispensable resource in modern science and information technology. Fortunately, an experimentally simple procedure exists to generate randomness with well-characterized devices: measuring a quantum system in a basis complementary to its preparation. Towards realizing this goal one may consider using atoms or superconducting qubits, promising candidates for quantum information processing. However, their unavoidable interaction with the electromagnetic field affects their dynamics. At large time scales, this can result in decoherence. Smaller time scales in principle avoid this problem, but may not be well analyzed under the usual rotating wave and single mode approximation (RWA and SMA) which break the relativistic nature of quantum field theory. Here, we use a fully relativistic analysis to quantify the information that an adversary with access to the field could get on the result of an atomic measurement. Surprisingly, we find that the adversary's guessing probability is not minimized for atoms initially prepared in the ground state (an intuition derived from the RWA and SMA model).