A coarse-grained Schrödinger cat

Author(s): J. Kofler, Č. Brukner

Title of the book: Quantum Communication and Security

Editor(s): Marek Żukowski, Sergei Kilin, Janusz Kowalik

Publisher: American Institute of Physics

Year of Publication: 2007


Link: Link to publication


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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