Quantum causal histories in the light of quantum information

Etera R. Livine*, Daniel R. Terno

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)
6 Downloads (Pure)


We use techniques of quantum information theory to analyze the quantum causal histories approach to quantum gravity. While it is consistent to introduce closed timelike curves (CTCs), they cannot generically carry independent degrees of freedom. Moreover, if the effective dynamics of the chronology-respecting part of the system is linear, it should be completely decoupled from the CTCs. In the absence of a CTC, not all causal structures admit the introduction of quantum mechanics. It is possible for those and only those causal structures that can be represented as quantum computational networks. Dynamics of the subsystems should not be unitary or even completely positive. However, we show that other commonly made assumptions ensure the complete positivity of the reduced dynamics.

Original languageEnglish
Article number084001
Pages (from-to)1-8
Number of pages8
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number8
Publication statusPublished - 2 Apr 2007

Bibliographical note

Copyright 2007 by The American Physical Society. Reprinted from Physical review D.


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