Self-testing two-qubit maximally entangled states from generalized Clauser-Horne-Shimony-Holt tests

Device-independent certification, also known as self-testing, aims at guaranteeing the proper functioning of untrusted and uncharacterized devices. For example, quality an unknown source expected to produce two-qubit maximally entangled states can be evaluated in a bi-partite scenario, each party using two binary measurements. The most robust approach consists deducing fidelity produced with respect state from violation CHSH inequality. In this paper, we show how self-testing is improved by refined analysis measurement statistics. use suitably chosen Bell tests, depending on observed correlations, allows one conclude higher fidelities than ones previously known. particular, nontrivial statements obtained correlations that cannot exploited CHSH-based strategy. Our results not only provide novel insight into set quantum suited for but facilitate experimental implementations device-independent certifications.