Journal article
Cyclic quantum causal models
- Abstract:
- Causal reasoning is essential to science, yet quantum theory challenges it. Quantum correlations violating Bell inequalities defy satisfactory causal explanations within the framework of classical causal models. What is more, a theory encompassing quantum systems and gravity is expected to allow causally nonseparable processes featuring operations in indefinite causal order, defying that events be causally ordered at all. The first challenge has been addressed through the recent development of intrinsically quantum causal models, allowing causal explanations of quantum processes – provided they admit a definite causal order, i.e. have an acyclic causal structure. This work addresses causally nonseparable processes and offers a causal perspective on them through extending quantum causal models to cyclic causal structures. Among other applications of the approach, it is shown that all unitarily extendible bipartite processes are causally separable and that for unitary processes, causal nonseparability and cyclicity of their causal structure are equivalent.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, 1.0MB, Terms of use)
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- Publisher copy:
- 10.1038/s41467-020-20456-x
Authors
- Publisher:
- Nature Research
- Journal:
- Nature Communications More from this journal
- Volume:
- 12
- Article number:
- 885
- Publication date:
- 2021-02-09
- Acceptance date:
- 2020-12-02
- DOI:
- EISSN:
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2041-1723
- Language:
-
English
- Keywords:
- Pubs id:
-
1149926
- Local pid:
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pubs:1149926
- Deposit date:
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2020-12-16
Terms of use
- Copyright holder:
- Barrett et al.
- Copyright date:
- 2021
- Rights statement:
- Copyright © 2021 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
- Licence:
- CC Attribution (CC BY)
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