Causally nonseparable processes admitting a causal model
A recent framework of quantum theory with no global causal order predicts the existence of ‘causally nonseparable’ processes. Some of these processes produce correlations incompatible with any causal order (they violate so-called ‘causal inequalities’ analogous to Bell inequalities ) while others do...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2016-01-01
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| Series: | New Journal of Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1367-2630/18/8/083040 |
| _version_ | 1797751000891654144 |
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| author | Adrien Feix Mateus Araújo Časlav Brukner |
| author_facet | Adrien Feix Mateus Araújo Časlav Brukner |
| author_sort | Adrien Feix |
| collection | DOAJ |
| description | A recent framework of quantum theory with no global causal order predicts the existence of ‘causally nonseparable’ processes. Some of these processes produce correlations incompatible with any causal order (they violate so-called ‘causal inequalities’ analogous to Bell inequalities ) while others do not (they admit a ‘causal model’ analogous to a local model ). Here we show for the first time that bipartite causally nonseparable processes with a causal model exist, and give evidence that they have no clear physical interpretation. We also provide an algorithm to generate processes of this kind and show that they have nonzero measure in the set of all processes. We demonstrate the existence of processes which stop violating causal inequalities but are still causally nonseparable when mixed with a certain amount of ‘white noise’. This is reminiscent of the behavior of Werner states in the context of entanglement and nonlocality. Finally, we provide numerical evidence for the existence of causally nonseparable processes which have a causal model even when extended with an entangled state shared among the parties. |
| first_indexed | 2024-03-12T16:40:59Z |
| format | Article |
| id | doaj.art-f0a64b293bef40989b7c0bcebcaf6a19 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:40:59Z |
| publishDate | 2016-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-f0a64b293bef40989b7c0bcebcaf6a192023-08-08T14:31:04ZengIOP PublishingNew Journal of Physics1367-26302016-01-0118808304010.1088/1367-2630/18/8/083040Causally nonseparable processes admitting a causal modelAdrien Feix0Mateus Araújo1Časlav Brukner2Faculty of Physics, University of Vienna , Boltzmanngasse 5, A-1090 Vienna, Austria; Institute for Quantum Optics and Quantum Information (IQOQI) , Boltzmanngasse 3, A-1090 Vienna, AustriaFaculty of Physics, University of Vienna , Boltzmanngasse 5, A-1090 Vienna, Austria; Institute for Quantum Optics and Quantum Information (IQOQI) , Boltzmanngasse 3, A-1090 Vienna, AustriaFaculty of Physics, University of Vienna , Boltzmanngasse 5, A-1090 Vienna, Austria; Institute for Quantum Optics and Quantum Information (IQOQI) , Boltzmanngasse 3, A-1090 Vienna, AustriaA recent framework of quantum theory with no global causal order predicts the existence of ‘causally nonseparable’ processes. Some of these processes produce correlations incompatible with any causal order (they violate so-called ‘causal inequalities’ analogous to Bell inequalities ) while others do not (they admit a ‘causal model’ analogous to a local model ). Here we show for the first time that bipartite causally nonseparable processes with a causal model exist, and give evidence that they have no clear physical interpretation. We also provide an algorithm to generate processes of this kind and show that they have nonzero measure in the set of all processes. We demonstrate the existence of processes which stop violating causal inequalities but are still causally nonseparable when mixed with a certain amount of ‘white noise’. This is reminiscent of the behavior of Werner states in the context of entanglement and nonlocality. Finally, we provide numerical evidence for the existence of causally nonseparable processes which have a causal model even when extended with an entangled state shared among the parties.https://doi.org/10.1088/1367-2630/18/8/083040quantum informationcausalityprocess matrixquantum mechanics |
| spellingShingle | Adrien Feix Mateus Araújo Časlav Brukner Causally nonseparable processes admitting a causal model New Journal of Physics quantum information causality process matrix quantum mechanics |
| title | Causally nonseparable processes admitting a causal model |
| title_full | Causally nonseparable processes admitting a causal model |
| title_fullStr | Causally nonseparable processes admitting a causal model |
| title_full_unstemmed | Causally nonseparable processes admitting a causal model |
| title_short | Causally nonseparable processes admitting a causal model |
| title_sort | causally nonseparable processes admitting a causal model |
| topic | quantum information causality process matrix quantum mechanics |
| url | https://doi.org/10.1088/1367-2630/18/8/083040 |
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