2021/01/31 by Giulio Foletto, Matteo Padovan, Marco Avesani +3
Computer Science · Mathematics · Medicine · Physics and Astronomy · #Bell's theorem #Biofield Effects and Biophysics #Mathematics #Physics #Quantum #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum entanglement #Quantum mechanics #Quantum nonlocality #Quantum state #Randomness #Randomness tests #Robustness (evolution) #Statistical physics #Statistics #Weak measurement #quant-ph
paper · pdf · doi:10.1103/physreva.103.062206
published as Phys. Rev. A 103, 062206 (2021) · 9 pages, 6 figures
openalex publication_date 2021/06/02 · arxiv created 2021/08/03 · arxiv updated 2021/08/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Quantum nonlocality offers a secure way to produce random numbers: Their unpredictability is intrinsic and can be certified just by observing the statistic of the measurement outcomes, without assumptions on how they are produced. To do this, entangled pairs are generated and measured to violate a Bell inequality with the outcome statistics. However, after a projective quantum measurement, entanglement is entirely destroyed and cannot be used again. This fact poses an upper bound to the amount of randomness that can be produced from each quantum state when projective measurements are employed. Instead, by using weak measurements, some entanglement can be maintained and reutilized, and a sequence of weak measurements can extract an unbounded amount of randomness from a single state as predicted in [Phys. Rev. A 95, 020102(R) (2017)]. We study the feasibility of these weak measurements, analyze the robustness to imperfections in the quantum state they are applied to, and then test them using an optical setup based on polarization-entangled photon pairs. We show that the weak measurements are realizable, but can improve the performance of randomness generation only in close-to-ideal conditions.