The simplest causal inequalities and their violation
- Author(s)
- Cyril Branciard, Mateus Araújo, Adrien Feix, Fabio Michele Costa, Caslav Brukner
- Abstract
In a scenario where two parties share, act on and exchange some physical resource, the assumption that the parties' actions are ordered according to a definite causal structure yields constraints on the possible correlations that can be established. We show that the set of correlations that are compatible with a definite causal order forms a polytope, whose facets define causal inequalities. We fully characterize this causal polytope in the simplest case of bipartite correlations with binary inputs and outputs. We find two families of nonequivalent causal inequalities; both can be violated in the recently introduced framework of process matrices, which extends the standard quantum formalism by relaxing the implicit assumption of a fixed causal structure. Our work paves the way to a more systematic investigation of causal inequalities in a theory-independent way, and of their violation within the framework of process matrices.
- Organisation(s)
- Quantum Optics, Quantum Nanophysics and Quantum Information
- External organisation(s)
- Institut NÉEL (CNRS), Österreichische Akademie der Wissenschaften (ÖAW), University of Queensland
- Journal
- New Journal of Physics
- Volume
- 18
- No. of pages
- 14
- ISSN
- 1367-2630
- DOI
- https://doi.org/10.1088/1367-2630/18/1/013008
- Publication date
- 01-2016
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103025 Quantum mechanics
- Keywords
- ASJC Scopus subject areas
- General Physics and Astronomy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/fbed8301-16aa-4578-afe4-798d8297e9b2