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Bell scenarios are multipartite scenarios that exclude any signalling between parties. This leads to a strict hierarchy of classical, quantum, and non-signalling correlations in such scenarios. Here we consider a minimal relaxation of…

Quantum Physics · Physics 2025-07-01 Ravi Kunjwal , Ognyan Oreshkov

Bell's theorem states that quantum correlation function of two spins can not be represented as an expectation value of two classical random variables. Spin is described in Bell's model by a single scalar random variable. We discuss another…

Quantum Physics · Physics 2007-05-23 Igor Volovich , Yaroslav Volovich

Understanding cause-effect relationships is a crucial part of the scientific process. As Bell's theorem shows, within a given causal structure, classical and quantum physics impose different constraints on the correlations that are…

Quantum Physics · Physics 2021-02-09 V. Vilasini , Roger Colbeck

Bell inequalities follow from a set of seemingly natural assumptions about how to provide a causal model of a Bell experiment. In the face of their violation, two types of causal models that modify some of these assumptions have been…

Quantum Physics · Physics 2022-05-11 Patrick J. Daley , Kevin J. Resch , Robert W. Spekkens

It is known that the classical framework of causal models is not general enough to allow for causal reasoning about quantum systems. While the framework has been generalized in a variety of different ways to the quantum case, much of this…

Quantum Physics · Physics 2020-11-23 Jonathan Barrett , Robin Lorenz , Ognyan Oreshkov

Quantum mechanics admits correlations that cannot be explained by local realistic models. Those most studied are the standard local hidden variable models, which satisfy the well-known Bell inequalities. To date, most works have focused on…

Quantum Physics · Physics 2017-06-01 Dylan J. Saunders , Adam J. Bennet , Cyril Branciard , Geoff J. Pryde

Bell's theorem is typically understood as the proof that quantum theory is incompatible with local-hidden-variable models. More generally, we can see the violation of a Bell inequality as witnessing the impossibility of explaining quantum…

Bell scenarios are multipartite scenarios that exclude any communication between parties. This constraint leads to a strict hierarchy of correlation sets in such scenarios, namely, classical, quantum, and nonsignaling. However, without any…

Quantum Physics · Physics 2026-05-29 Ravi Kunjwal , Ognyan Oreshkov

Analyzing the geometry of correlation sets constrained by general causal structures is of paramount importance for foundational and quantum technology research. Addressing this task is generally challenging, prompting the development of…

Using a process-theoretic formalism, we introduce the notion of a causal-inferential theory: a triple consisting of a theory of causal influences, a theory of inferences (of both the Boolean and Bayesian varieties), and a specification of…

Quantum Physics · Physics 2021-05-21 David Schmid , John H. Selby , Robert W. Spekkens

The problem of using observed correlations to infer causal relations is relevant to a wide variety of scientific disciplines. Yet given correlations between just two classical variables, it is impossible to determine whether they arose from…

The fields of quantum non-locality in physics, and causal discovery in machine learning, both face the problem of deciding whether observed data is compatible with a presumed causal relationship between the variables (for example a local…

Quantum Physics · Physics 2014-06-02 Rafael Chaves , Lukas Luft , David Gross

Bell's Theorem shows that quantum mechanical correlations can violate the constraints that the causal structure of certain experiments impose on any classical explanation. It is thus natural to ask to which degree the causal assumptions --…

Quantum Physics · Physics 2015-04-16 Rafael Chaves , Richard Kueng , Jonatan Bohr Brask , David Gross

Quantum networks are the center of many of the recent advances in quantum science, not only leading to the discovery of new properties in the foundations of quantum theory but also allowing for novel communication and cryptography…

Nonlocality and contextuality are at the root of conceptual puzzles in quantum mechanics, and are key resources for quantum advantage in information-processing tasks. Bell nonlocality is best understood as the incompatibility between…

Quantum Physics · Physics 2019-02-18 Eric G. Cavalcanti

This thesis reports progress in the analysis of causality and multi-agent logical paradoxes in quantum and post-quantum theories. These research areas are highly relevant for the foundations of physics as well as the development of quantum…

Quantum Physics · Physics 2021-02-05 V. Vilasini

We present a method that allows the study of classical and quantum correlations in networks with causally-independent parties, such as the scenario underlying entanglement swapping. By imposing relaxations of factorization constraints in a…

Causal networks beyond that in the paradigmatic Bell's theorem can lead to new kinds and applications of non-classical behavior. Their study, however, has been hindered by the fact that they define a non-convex set of correlations and only…

Quantum Physics · Physics 2023-11-16 Giulio Camillo , Pedro Lauand , Davide Poderini , Rafael Rabelo , Rafael Chaves

Bell's Theorem witnesses that the predictions of quantum theory cannot be reproduced by theories of local hidden variables in which observers can choose their measurements independently of the source. Working out an idea of Branciard,…

Quantum Physics · Physics 2012-10-03 Tobias Fritz

Causal reasoning is essential to science, yet quantum theory challenges it. Quantum correlations violating Bell inequalities defy satisfactory causal explanations within the framework of classical causal models. What is more, a theory…

Quantum Physics · Physics 2021-03-05 Jonathan Barrett , Robin Lorenz , Ognyan Oreshkov