Bounding the sets of classical and quantum correlations in networks

• Main Author: Pozas-Kerstjens, Alejandro
• Publication Date: 2019
• Other Authors: Rabelo, Rafael, Rudnicki, Łukasz, Araújo, Rafael Chaves Souto, Cavalcanti, Daniel, Navascu´es, Miguel, Acín, Antonio
• Format: Article
• Language: eng
• Source: Repositório Institucional da UFRN
• Download full: https://repositorio.ufrn.br/handle/123456789/30207
• topic: Entanglement swapping; Quantum networks

We present a method that allows the study of classical and quantum correlations in networks with causally independent parties, such as the scenario underlying entanglement swapping. By imposing relaxations of factorization constraints in a form compatible with semidefinite programing, it enables the use of the Navascu´es-Pironio-Acín hierarchy in complex quantum networks. We first show how the technique successfully identifies correlations not attainable in the entanglement-swapping scenario. Then we use it to show how the nonlocal power of measurements can be activated in a network: there exist measuring devices that, despite being unable to generate nonlocal correlations in the standard Bell scenario, provide a classical-quantum separation in an entanglement swapping configuration