How device-independent approaches change the meaning of physical theory

Abstract

Dirac sought an interpretation of mathematical formalism in terms of physical entities and Einstein insisted that physics should describe "the real states of the real systems". While Bell inequalities put into question the reality of states, modern device-independent approaches do away with the idea of entities: physical theory may contain no physical systems. Focusing on the correlations between operationally defined inputs and outputs, device-independent methods promote a view more distant from the conventional one than Einstein's 'principle theories' were from 'constructive theories'. On the examples of indefinite causal orders and almost quantum correlations, we ask a puzzling question: if physical theory is not about systems, then what is it about? The answer given by the device-independent models is that physics is about languages. In moving away from the information-theoretic reconstructions of quantum theory, this answer marks a new conceptual development in the foundations of physics.

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• Sharing nonfungible information requires shared nonfungible information
• Quantum Reconstructions as Stepping Stones toward Psi-Doxastic Interpretations?
• The operational framework for quantum theories is both epistemologically and ontologically neutral
• Against 'Particle Metaphysics' and 'Collapses' within the Definition of Quantum Entanglement
• Defending the Quantum Reconstruction Program
• Translating Bell Non-Locality to Prepare-and-Measure Scenarios under Dimensional Constraints
• Contextuality, Witness of Quantum Weirdness
• Whether a quantum computation employs nonlocal resources is operationally undecidable
• Ruling out the class of statistical processes involving two noninteracting identical particles in two modes
• Anomalous non-classicality via correlative and entropic Bell inequalities