Entanglement of electrons field-emitted from a superconductor

Department of Applied Physics and Advanced Institute for Complex Systems, Waseda University, Tokyo 169-8555, Japan(April 22, 2009)Under appropriate circumstances the electrons emitted from a superconducting tip can be en-tangled. We analyze these nonlocal correlations by studying the coincidences of the field-emittedelectrons and show that electrons emitted in opposite directions violate Bell’s inequality. We scruti-nize the interplay between the bosonic nature of Cooper pairs and the fermionic nature of electrons.We further discuss the feasibility of our analysis in the light of present experimental capabilities.