Possibilistic and maximal indefinite causal order in the quantum switch

Fuente: arXiv
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Autori principali: van der Lugt, Tein, Ormrod, Nick
Natura: Preprint
Pubblicazione: 2023
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author van der Lugt, Tein
Ormrod, Nick
author_facet van der Lugt, Tein
Ormrod, Nick
contents It was recently found that the indefinite causal order in the quantum switch can be certified device-independently when assuming the impossibility of superluminal influences. Here we strengthen this result in two ways. First, we give a proof of this fact which is possibilistic rather than probabilistic, i.e. which does not rely on the validity of probability theory at the hidden variable level. Then, returning to the probabilistic setting, we show that the indefinite causal order in the quantum switch is also maximal, in the sense that the observed correlations are incompatible even with the existence of a causal order on only a small fraction of the runs of the experiment. While the original result makes use of quantum theory's violation of a Clauser-Horne-Shimony-Holt inequality, the proofs presented here are based on Greenberger, Horne, and Zeilinger's and Mermin's proofs of nonlocality, respectively.
format Preprint
id arxiv_https___arxiv_org_abs_2311_00557
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Possibilistic and maximal indefinite causal order in the quantum switch
van der Lugt, Tein
Ormrod, Nick
Quantum Physics
It was recently found that the indefinite causal order in the quantum switch can be certified device-independently when assuming the impossibility of superluminal influences. Here we strengthen this result in two ways. First, we give a proof of this fact which is possibilistic rather than probabilistic, i.e. which does not rely on the validity of probability theory at the hidden variable level. Then, returning to the probabilistic setting, we show that the indefinite causal order in the quantum switch is also maximal, in the sense that the observed correlations are incompatible even with the existence of a causal order on only a small fraction of the runs of the experiment. While the original result makes use of quantum theory's violation of a Clauser-Horne-Shimony-Holt inequality, the proofs presented here are based on Greenberger, Horne, and Zeilinger's and Mermin's proofs of nonlocality, respectively.
title Possibilistic and maximal indefinite causal order in the quantum switch
topic Quantum Physics
url https://arxiv.org/abs/2311.00557