Proper and improper density matrices and the consistency of the Deutsch model for Local Closed Timelike Curves
Allen Lobo, Ismael L. Paiva, Pedro R. Dieguez · arXiv (Cornell University) · 2011
We discuss the concept of proper and improper density matrixes and we argue that this issue is of fundamental importance for the understanding of the quantum-mechanical CTC model proposed by Deutsch. We arrive at the conclusion that under a realistic interpretation, the distinction between proper and improper density operators is not a relativistically covariant notion and this fact leads to the conclusion that the D-CTC model is physically inconsistent.