Mercredi 03 juillet 2013 à 10h15
Salle 234, Ecole de Physique

Full counting statistics of Andreev events

Ville F. Maisi, Aalto University, Helsinki, Finland

The full counting statistics (FCS) of charge transfer in nano-electronic circuits provides information about fundamental tunneling processes. FCS is not limited to normal-state conductors, but may equally well describe charge fluctuations in superconducting materials. Nevertheless, despite considerable theoretical interest in the FCS of superconductors, experiments have so far been restricted to normal-state electrons. Here we measure the FCS of Andreev events in which Cooper pairs are either produced from electrons that are reflected as holes at a superconductor/normal-state interface or annihilated in the reverse process. Surprisingly, the FCS consists of quiet periods with no Andreev processes interrupted by the tunneling of a single electron that triggers an avalanche of Andreev events giving rise to strongly super-Poissonian distributions. Our experiment is important for quantum metrological applications and for entanglement generation using Cooper pair splitters.