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Quantum non-locality based on finite-speed causal influences leads to superluminal signalling

Nature Physics volume 8, pages 867870 (2012) | Download Citation

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Abstract

The experimental violation of Bell inequalities using space-like separated measurements precludes the explanation of quantum correlations through causal influences propagating at subluminal speed1,2. Yet, any such experimental violation could always be explained in principle through models based on hidden influences propagating at a finite speed v>c, provided v is large enough3,4. Here, we show that for any finite speed v with , such models predict correlations that can be exploited for faster-than-light communication. This superluminal communication does not require access to any hidden physical quantities, but only the manipulation of measurement devices at the level of our present-day description of quantum experiments. Hence, assuming the impossibility of using non-local correlations for superluminal communication, we exclude any possible explanation of quantum correlations in terms of influences propagating at any finite speed. Our result uncovers a new aspect of the complex relationship between multipartite quantum non-locality and the impossibility of signalling.

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Acknowledgements

We acknowledge S. Massar and T. Vértesi for helpful discussions as well as J. Silman, E. Cavalcanti, T. Barnea and S. Portmann for comments on the manuscript. This work was supported by the European ERC AG Qore and SG PERCENT, the European EU FP7 QCS and Q-Essence projects, the CHIST-ERA DIQIP project, the Swiss NCCRs QP and QSIT, the Interuniversity Attraction Poles Photonics@be Programme (Belgian Science Policy), the Brussels-Capital Region through a BB2B Grant, the Spanish FIS2010-14830 project, the National Research Foundation and the Ministry of Education of Singapore.

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Affiliations

  1. Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland

    • J-D. Bancal
    • , Y-C. Liang
    •  & N. Gisin
  2. Laboratoire d’Information Quantique, Université Libre de Bruxelles, 1050 Bruxelles, Belgium

    • S. Pironio
  3. ICFO-Institut de Ciències Fotòniques, Castelldefels (Barcelona), 08860 Castelldefels (Barcelona), Spain

    • A. Acín
  4. ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, 08010 Barcelona, Spain

    • A. Acín
  5. Centre for Quantum Technologies, National University of Singapore, Singapore 117543, Singapore

    • V. Scarani
  6. Department of Physics, National University of Singapore, Singapore 117542, Singapore

    • V. Scarani

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All authors participated at various levels in the results presented here and in the writing of the article.

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The authors declare no competing financial interests.

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Correspondence to J-D. Bancal.

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https://doi.org/10.1038/nphys2460

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