Large violation of Bell inequalities using both particle andwave measurements

Daniel Cavalcanti, Nicolas Brunner, Paul Skrzypczyk, Alejo Salles, and Valerio Scarani
Phys. Rev. A 84, 022105 – Published 8 August 2011

Abstract

When separated measurements on entangled quantum systems are performed, the theory predicts correlations that cannot be explained by any classical mechanism: communication is excluded because the signal should travel faster than light; preestablished agreement is excluded because Bell inequalities are violated. All optical demonstrations of such violations have involved discrete degrees of freedom and are plagued by the detection-efficiency loophole. A promising alternative is to use continuous variables combined with highly efficient homodyne measurements. However, all the schemes proposed so far use states or measurements that are extremely difficult to achieve, or they produce very weak violations. We present a simple method to generate large violations for feasible states using both photon counting and homodyne detections. The present scheme can also be used to obtain nonlocality from easy-to-prepare Gaussian states (e.g., two-mode squeezed state).

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  • Received 31 January 2011

DOI:https://doi.org/10.1103/PhysRevA.84.022105

©2011 American Physical Society

Authors & Affiliations

Daniel Cavalcanti1,*, Nicolas Brunner2, Paul Skrzypczyk2, Alejo Salles3, and Valerio Scarani1,4

  • 1Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543
  • 2H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
  • 3Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
  • 4Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542

  • *dcavalcanti@gmail.com

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Issue

Vol. 84, Iss. 2 — August 2011

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