We show that under coarse-grained measurements there is no observational difference between a quantum superposition of macroscopically distinct states (“Scrödinger-cat states”) and a classical mixture of these states. Since normally our observations in every-day life are of limited accuracy, no quantum features can be observed. Remarkably, the information gain in such classical coarse-grained measurements is only half of the maximal information gain in sharp quantum measurements. This suggests a novel approach to macroscopic realism and classical physics within quantum theory.
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