Large violation of Bell inequalities using both particle and wave measurements

Daniel Cavalcanti*, Nicolas Brunner, Paul Skrzypczyk, Alejo Salles, Valerio Scarani

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review


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).

Original languageEnglish
Article number022105
Number of pages4
JournalPhysical Review A: Atomic, Molecular and Optical Physics
Issue number2
Publication statusPublished - 8 Aug 2011



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