Detecting nonlocality in many-body quantum states

Detecting nonlocality in many-body quantum states

Seminar author:Jordi Tura

Event date and time:11/11/2014 03:30:pm

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One of the most important steps in the understanding of quantum many-body systems is due to the intensive studies of their entanglement properties. Much less, however, is known about the role of quantum nonlocality in these systems. This is because standard many-body observables involve correlations among few particles, while there is no multipartite Bell inequality for this scenario. Here we provide the first example of nonlocality detection in many-body systems using only two-body correlations. To this aim, we construct families of multipartite Bell inequalities that involve only second order correlations of local observables. We then provide examples of systems, relevant for nuclear and atomic physics, whose ground states violate our Bell inequalities for any number of constituents. Finally, we identify inequalities that can be tested by measuring collective spin components, opening the way to the experimental detection of many-body nonlocality, for instance with atomic ensembles.

The talk will be based on the following studies
[1] J. Tura, R. Augusiak, A. B. Sainz, T. Vértesi, M. Lewenstein and A. Acín, Science 344 6189 pp. 1256-1258
[2] J. Tura, A. B. Sainz, T. Vértesi, M. Lewenstein, A. Acín and R. Augusiak, J. Phys. A: Math. Theor. 47 424024
[3] J. Tura et al., in preparation