Full counting statistics of electron transfer between superconductors - art. no. 197006

We present an extension of the Keldysh-Green's function method, which allow s one to calculate the full distribution of transmitted particles through a mesoscopic superconductor. The method is applied to the statistics of supe rcurrent in short contacts. If the current is carried by Andreev bound stat es the distribution corresponds to switching between long trains of electro ns going in opposite directions. For weak (gapless) superconductors or tunn el junctions we find that at low temperatures the distribution has negative "probabilities." Accounting for the quantum mechanical nature of the measu ring device shows that these negative values can indeed be measured.