We investigate the emission of entangled electron pairs from a superconductor into a normal metal through a tunnelling interface of arbitrary size. We establish the equivalence between hole Andreev reflection and two-electron emission, ascribing each picture to a different choice of normal vacuum. The case of a tunnelling interface made of two point-like apertures is analyzed. We show that the distance dependence of the non-locally entangled current is very sensitive to the choice of tunnelling Hamiltonian. Finally, we investigate a resonant tunnelling structure which emits the entangled electrons in diverging directions thus solving the problem of spatial beamseparation.
Work done in collaboration with Elsa Prada (UAM and Univ. Karlsruhe).