Experimental Full-Domain Mapping of Quantum Correlation in Clauser-Horne-Shimony-Holt Scenarios

Quantum correlation between two parties serves as a useful resource in the surging applications of quan-tum information. The Bell nonlocality and quantum steering have been proposed to describe nonclassicalcorrelations against local-hidden-variable and local-hidden-state theories, respectively. To characterizethe two types of nonclassical correlations, various nonlocality and steering inequalities have been estab-lished, and the amount of inequality violation serves as a helpful indicator for many entanglement-basedtasks. Quantum state tomography has been employed for measuring quantum states, while the methodrequires intensive computation and does not directly verify either nonlocality or steering over the fulldomain independent of established theories. Here, we experimentally map the full-domain correlationwith bipartite states for nonlocality and quantum steering in Clauser-Horne-Shimony-Holt scenarios. Themeasurement of the maps automatically accounts for detection imperfections. Furthermore, we demon-strate the application of the correlation maps in the entanglement-based quantum key distribution protocolwith arbitrary bipartite states. The correlation maps show direct measurements and simple interpretationsthat can answer fundamental questions about nonlocality and quantum steering as well as contribute toquantum information applications in a straightforward manner.

Automated summary

Experimental measurement of quantum correlation is used to establish nonlocality and entanglement inequalities, which are employed to test nonclassical correlations. The correlation maps are applied in an entanglement-based quantum key distribution protocol.