Violation of Bell inequalities with photon counting and homodyne measurements - Daniel Cavalcanti

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; pre-established 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 produce very weak violations. In this talk I will present a simple method to generate large violations for feasible states using both photon counting and homodyne detections. The present scheme can be used to obtain nonlocality from easy-to-prepare Gaussian states (e.g. two-mode squeezed state) and requires efficiencies comparable to the best tests involving discrete variables.