title: Activation of nonlocal quantum resources.
abstract: We find two two-qubit bipartite states ρ1, ρ2 such that arbitrarily many copies of one or the other cannot exhibit nonlocal correlations in a two-setting-two-outcome Bell scenario. However, the bipartite state ρ1 ⊗ ρ2 violates the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality [J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, Phys. Rev. Lett. 23, 880 (1969).] by an amount of 2.023. We also identify a CHSH-local state ρ such that ρ⊗2 is CHSH inequality-violating. The tools employed can be easily adapted to find instances of nonlocality activation in arbitrary Bell scenarios.
authors.affiliation: Departamento Análisis Matemático, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Navascués
authors.forename: Tamás
authors.initials: T
authors.lastname: Vértesi