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' rule 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.
Tue, 05.07.2022 15:00