Randomness versus Nonlocality and Entanglement

Antonio Acín, Serge Massar, and Stefano Pironio
Phys. Rev. Lett. 108, 100402 – Published 9 March 2012
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Abstract

The outcomes obtained in Bell tests involving two-outcome measurements on two subsystems can, in principle, generate up to 2 bits of randomness. However, the maximal violation of the Clauser-Horne-Shimony-Holt inequality guarantees the generation of only 1.23 bits of randomness. We prove here that quantum correlations with arbitrarily little nonlocality and states with arbitrarily little entanglement can be used to certify that close to the maximum of 2 bits of randomness are produced. Our results show that nonlocality, entanglement, and randomness are inequivalent quantities. They also imply that device-independent quantum key distribution with an optimal key generation rate is possible by using almost-local correlations and that device-independent randomness generation with an optimal rate is possible with almost-local correlations and with almost-unentangled states.

  • Figure
  • Received 17 October 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.100402

© 2012 American Physical Society

Authors & Affiliations

Antonio Acín1,2, Serge Massar3, and Stefano Pironio3

  • 1ICFO-Institut de Ciencies Fotoniques, Avenida Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain
  • 2ICREA-Institució Catalana de Recerca i Estudis Avançats, Lluis Companys 23, 08010 Barcelona, Spain
  • 3Laboratoire d’Information Quantique, Université Libre de Bruxelles, Brussels, Belgium

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Issue

Vol. 108, Iss. 10 — 9 March 2012

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