SAMOP 2023 – scientific programme

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QI: Fachverband Quanteninformation

QI 34: Concepts and Methods III

QI 34.5: Talk

Friday, March 10, 2023, 12:00–12:15, B302

Device-independent randomness extraction from almost separable multipartite states — •Giacomo Carrara, Federico Grasselli, Hermann Kampermann, Dagmar Bruß, and Gláucia Murta — Heinrich-Heine-Universität Düsseldorf

Bell inequalities represent a fundamental tool for many quantum information tasks that exploit nonlocality. In particular they can be used for device-independent (DI) protocols, where the parties do not need to trust or characterize the underlying systems and measurement devices. Specifically, the violation of a Bell inequality allows to certify the randomness of the parties’ outcomes with respect to a potential eavesdropper. Even though entanglement is necessary for the violation of a Bell inequality, the relation between nonlocality and entanglement is more intricate than one might expect. In [Phys. Rev. Lett., 108, 100402 (2012)] the authors show that maximal DI randomness can be obtained, in the bipartite scenario, from almost separable states. In this work, we extend this result to the multipartite scenario. In particular, we analyze the amount of randomness that can be extracted from a state arbitrarily close to a fully separable state using a suitably chosen multipartite Bell inequality. In order to achieve this result, we employ both standard numerical convex optimization and analytical methods.