Navegando por Autor "Wolfe, Elie"
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Artigo Causal Networks and Freedom of Choice in Bell’s Theorem(PRX Quantum, 2021-11-03) Araújo, Rafael Chaves Souto; Moreno Filho, Marcos George Magalhães; Polino, Emanuele; Poderini, Davide; Agresti, Iris; Suprano, Alessia; Barros, Mariana Rodrigues; Carvacho, Gonzalo; Wolfe, Elie; Canabarro, Askery; Spekkens, Robert W.; Sciarrino, FabioBell’s theorem is typically understood as the proof that quantum theory is incompatible with local-hidden-variable models. More generally, we can see the violation of a Bell inequality as witnessing the impossibility of explaining quantum correlations with classical causal models. The violation of a Bell inequality, however, does not exclude classical models where some level of measurement dependence is allowed, that is, the choice made by observers can be correlated with the source generating the systems to be measured. Here, we show that the level of measurement dependence can be quantitatively upper bounded if we arrange the Bell test within a network. Furthermore, we also prove that these results can be adapted in order to derive nonlinear Bell inequalities for a large class of causal networks and to identify quantumly realizable correlations that violate them.Artigo Experimental genuine tripartite nonlocality in a quantum triangle network(PRX Quantum, 2022-09-21) Araújo, Rafael Chaves Souto; Poderini, Davide; Polino, Emanuele; Agresti, Iris; Vera, Gonzalo Alfredo Carvacho; Canabarro, Askery; Wolfe, Elie; Suprano, Alessia; Sciarrino, FabioQuantum networks are the center of many of the recent advances in quantum science, not only leading to the discovery of new properties in the foundations of quantum theory but also allowing for novel communication and cryptography protocols. It is known that networks beyond that in the paradigmatic Bell’s theorem imply new and sometimes stronger forms of nonclassicality. Due to a number of practical difficulties, however, the experimental implementation of such networks remains far less explored. Going beyond what has been previously tested, here we verify the nonlocality of an experimental triangle network, consisting of three independent sources of bipartite entangled photon states interconnecting three distant parties. By performing separable measurements only and evaluating parallel chained Bell inequalities, we show that such networks can lead to a genuine form of tripartite nonlocality, where classical models are unable to mimic the quantum predictions even if some of the parties are allowed to communicateArtigo Experimental nonclassicality in a causal network without assuming freedom of choice(Nature Communications, 2023-02-17) Polino, Emanuele; Poderini, Davide; Rodari, Giovanni; Agresti, Iris; Suprano, Alessia; Carvacho, Gonzalo; Wolfe, Elie; Canabarro, Askery; Moreno Filho, Marcos George Magalhães; Milani, Giorgio; Spekkens, Robert W.; Araújo, Rafael Chaves Souto; Sciarrino, FabioIn a Bell experiment, it is natural to seek a causal account of correlations wherein only a common cause acts on the outcomes. For this causal structure, Bell inequality violations can be explained only if causal dependencies are modeled as intrinsically quantum. There also exists a vast landscape of causal structures beyond Bell that can witness nonclassicality, in some cases without even requiring free external inputs. Here, we undertake a photonic experiment realizing one such example: the triangle causal network, consisting of three measurement stations pairwise connected by common causes and no external inputs. To demonstrate the nonclassicality of the data, we adapt and improve three known techniques: (i) a machine-learning-based heuristic test, (ii) a data-seeded inflation technique generating polynomial Bell-type inequalities and (iii) entropic inequalities. The demonstrated experimental and data analysis tools are broadly applicable paving the way for future networks of growing complexity