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.