1110.6361 (A. C. Lobo et al.)

The ontological status of density matrices and the consistency of the
Deutsch CTC model    [PDF]

A. C. Lobo, I. L. Paiva, P. R. Dieguez

We discuss the ontological status of the density matrix concept, and we
advance the argument 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.

View original: http://arxiv.org/abs/1110.6361