Incompatibility between Realism and Quantum Mechanics: A Simple Example

Pablo L. Saldanha

Published 2018-05-14Version 1

We show that it is not possible to ascribe an objective reality to a property of a quantum system even if the system is in an eigenstate of the corresponding observable and a measurement of the property is certain to result in a particular value. This kind of incompatibility between realism and quantum mechanics is theoretically demonstrated with a simple example where sequential angular momentum measurements are performed on a quantum system. We discuss the relation of this result with other investigations about realism and quantum mechanics. In particular, we show that the Einstein-Podolsky-Rosen criterion for physical reality is incompatible with the quantum theory.