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Séminaire : jeudi 30 juin 2022 à 11h15

Manabandra Nath Bera (Indian Institute of Science Education and Research (IISER))

Titre : Does quantum Bayes’ rule affirm consistency in measurement inferences in quantum mechanics?


Institut Néel, Salle D420
Résumé : Classical Bayes’ rule lays the foundation for the classical causal relation between cause (input) and effect (output). This rule is believed to be universally true for all physical processes. On the contrary, we show that it is inadequate to establish correct correspondence between cause and effect in quantum mechanics. In fact, there are instances where the use of classical Bayes’ theorem leads to inconsistencies in quantum measurement inferences, such as Frauchiger-Renner’s paradox. As a remedy, we introduce a deterministic causal relation based on quantum Bayes’ rule. It applies to general quantum processes even when a cause (or effect) is in a coherent superposition with other causes (or effects) and involves nonlocal correlations as allowed by quantum mechanics. This enables us to propose a resolution to Frauchiger-Renner’s paradox and reaffirm that quantum mechanics can consistently explain its use. We discuss the consequences of our results.