Detecting entangled states in graphene via crossed Andreev reflection

Shot-noise cross correlations across single layer graphene structures are calculated with insulators separating a superconducting region. A different feature of specular crossed Andreev reflection comes into play due to the unique band structure of graphene. This gives rise to a rich structure in the states of the electric current flowing across the graphene sheet. We identified a parametric regime where positive shot-noise cross correlations of the current appear signifying entanglement. In contrast to previous proposals the sign of the cross correlations can be easily tuned by the application of a gate voltage.