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Experimental fully contextual correlations
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Departamento de Física Aplicada II, Universidad de Sevilla.
Department of Informatics, University of Bergen.
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(English)Article in journal (Refereed) Submitted
Abstract [en]

Quantum correlations are contextual yet, in general, nothing prevents the existence of even morecontextual correlations. We identify and test a simple noncontextual inequality in which the quantumviolation cannot be improved by any hypothetical post-quantum resource, and use it to experimentally obtain correlations in which the maximum noncontextual content, defined as the maximumfraction of noncontextual correlations, is less than 0.06. Our correlations are experimentally generated from the outcomes of sequential compatible measurements on a four-state quantum system encoded in the polarization and path of a single photon.

National Category
Atom and Molecular Physics and Optics
URN: urn:nbn:se:su:diva-66460OAI: diva2:467986
Available from: 2011-12-20 Created: 2011-12-20 Last updated: 2011-12-20Bibliographically approved
In thesis
1. Dynamics of Quantum Correlations with Photons: Experiments on bound entanglement and contextuality for application in quantum information
Open this publication in new window or tab >>Dynamics of Quantum Correlations with Photons: Experiments on bound entanglement and contextuality for application in quantum information
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The rapidly developing interdisciplinary field of quantum information, which merges quantum and information science, studies non-classical aspects of quantum systems. These studies are motivated by the promise that the non-classicality can be used to solve tasks more efficiently than classical methods would allow. In many quantum informational studies, non-classical behaviour is attributed to the notion of entanglement.

In this thesis we use photons to experimentally investigate fundamental questions such as: What happens to the entanglement in a system when it is affected by noise? In our study of noisy entanglement we pursue the challenging task of creating bound entanglement. Bound entangled states are created through an irreversible process that requires entanglement. Once in the bound regime, entanglement cannot be distilled out through local operations assisted by classical communication. We show that it is possible to experimentally produce four-photon bound entangled states and that a violation of a Bell inequality can be achieved. Moreover, we demonstrate an entanglement-unlocking protocol by relaxing the condition of local operations.

We also explore the non-classical nature of quantum mechanics in several single-photon experiments. In these experiments, we show the violation of various inequalities that were derived under the assumption of non-contextuality. Using qutrits we construct and demonstrate the simplest possible test that offers a discrepancy between classical and quantum theory. Furthermore, we perform an experiment in the spirit of the Kochen-Specker theorem to illustrate the state-independence of this theorem. Here, we investigate whether or not measurement outcomes exhibit fully contextual correlations. That is, no part of the correlations can be attributed to the non-contextual theory. Our results show that only a small part of the experimental generated correlations are amenable to a non-contextual interpretation.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2012. 102 p.
Quantum information, quantum optics, foundations of quantum mechanics, entanglement, non-contextuality, Kochen-Specker theorem, parametric down-conversion, quantum state engineering
National Category
Physical Sciences
Research subject
urn:nbn:se:su:diva-66469 (URN)978-91-7447-421-3 (ISBN)
Public defence
2012-01-26, FA31, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 5: Submitted. Paper 6: Submitted.

Available from: 2012-01-04 Created: 2011-12-20 Last updated: 2015-04-30Bibliographically approved

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Amselem, EliasBourennane, Mohamed
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