Steven Weinstein
Published 2008-07-22, updated 2008-10-26Version 2
We consider the claim that decoherence explains the emergence of classicality in quantum systems, and conclude that it does not. We show that, given a randomly chosen universe composed of a variety of subsystems, some of which are macroscopic and subject to decoherence-inducing interactions, and some of which are microscopic, the macroscopic subsystems will not display any distinctively classical behavior. Therefore, a universe in which macroscopic and microscopic do display distinct behavior must be in a very special, highly nongeneric quantum state.
Comments: Changed to emphasize the role of stability as a criterion for classicality, rather than diagonalization of the reduced density matrix. The conclusion is restated to emphasize that, irrespective of the dynamics, it is only for very special global quantum states that macroscopic objects will display behavior distinct from microscopic objects
Emergence of Classicality in Stern-Gerlach Experiment via Self-Gravity
Classicality from quantumness revealed by disturbance-free measurement
Two Roads to Classicality
![QR code for arXiv:0807.3376 [quant-ph]](http://oss.arxitics.com/images/favicon.svg)