Certified Randomness from a Two-Level System in a Relativistic Quantum Field

TL;DR

This paper investigates the generation of certified quantum randomness using atoms or superconducting qubits interacting with a relativistic quantum field, revealing that relativistic effects influence security assumptions.

Contribution

It provides a fully relativistic analysis of atomic measurement security, challenging previous assumptions based on non-relativistic models like RWA and SMA.

Findings

Adversary's guessing probability varies with initial atomic states.

Relativistic effects impact the security of quantum randomness protocols.

Ground state preparation does not minimize adversary's information as previously thought.

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 analysed 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).