Causation does not explain contextuality

Abstract

Realist interpretations of quantum mechanics presuppose the existence of elements of reality that are independent of the actions used to reveal them. Such a view is challenged by several no-go theorems that show quantum correlations cannot be explained by non-contextual ontological models, where physical properties are assumed to exist prior to and independently of the act of measurement. However, all such contextuality proofs assume a traditional notion of causal structure, where causal influence flows from past to future according to ordinary dynamical laws. This leaves open the question of whether the apparent contextuality of quantum mechanics is simply the signature of some exotic causal structure, where the future might affect the past or distant systems might get correlated due to non-local constraints. Here we show that quantum predictions require a deeper form of contextuality: even allowing for arbitrary causal structure, no model can explain quantum correlations from non-contextual ontological properties of the world, be they initial states, dynamical laws, or global constraints.

18+8 pages, 3 figures

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• Reassessing thermodynamic advantage from indefinite causal order
• Contextuality, Fine-Tuning, and Teleological Explanation
• Objective quantum fields, retrocausality and ontology
• No nonlocal advantage of quantum coherence beyond quantum instrumentality
• The Operational Choi-Jamiolkowski Isomorphism
• Classical and Quantum Causal Interventions
• The operational framework for quantum theories is both epistemologically and ontologically neutral
• A de Finetti theorem for quantum causal structures
• Introducing the Q-based interpretation of quantum theory
• Forward-backward stochastic simulations: Q-based model for measurement and Bell-nonlocality consistent with weak local realistic premises