Efficient Cooper Pair Splitting Without Interactions

For the three-terminal NSN device with single-mode normal terminals and without Coulomb blockade, we propose the interpretation of charge transfer process which allows us to consistently characterize the device operation as that of a Cooper pair splitter in terms of scattering matrix elements as well as in terms of measurable quantities. The obtained explicit expression for the splitting probability notably contains the two-particle interference term not available from conductance measurements. We show that splitting doesn’t necessarily rely on single-particle crossed Andreev reflection amplitude thus allowing for the unit efficiency at zero energy. Our results imply that the current cross-correlator generally doesn’t provide definite measure of splitting.