Quantum physics cannot be captured by classical linear hidden variable theories even in the absence of entanglement

Autor: Kawthar Al Rasbi, Lewis A. Clark, Almut Beige
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Frontiers in Physics, Vol 12 (2024)
Druh dokumentu: article
ISSN: 2296-424X
DOI: 10.3389/fphy.2024.1325239
Popis: Recent experimental tests of Bell inequalities confirm that entangled quantum systems cannot be described by local classical theories but still do not answer the question whether or not quantum systems could, in principle, be modeled by linear hidden variable theories. In this paper, we study the quantum trajectories of a single qubit that experiences a sequence of repeated generalized measurements. It is shown that this system, which constitutes a hidden quantum Markov model, is more likely to produce complex time correlations than any classical hidden Markov model with two output symbols. From this, we conclude that quantum physics cannot be replaced by linear hidden variable theories. Indeed, it has already been recognized that not only entanglement but also non-classical time correlations of quantum systems with quantum feedback are a valuable resource for quantum technology applications.
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