Jeudi 19 février 2015 à 10h15
Salle 234, Ecole de Physique

Statistics of charge transport and modified time ordering

Vincent Beaud, ETH Zürich

In the last 25 years a discrepancy arose about the 3rd cumulant of charge transport across a tunnel junction for independent fermionic carriers. Depending on settings and methods, it was found to be binomial or not. Our result removes the ambiguity in a model of energy-dependent scattering with quadratic dispersion relation. Independently, we treat the special case of a large detector and complete similar results of Bachmann, Graf and Lesovik (2010) on a model with linear dispersion relation. In all cases binomial statistics is confirmed. In this talk, after briefly reviewing some results and expectations, a generating function of counting statistics will be introduced and reformulated in terms of time-ordered current correlators. The ordering prescription will be shown to differ from the usual ones (Dyson and Keldysh) by the Matthews modification, inducing additional terms at coinciding times. Eventually, we shall present the model with quadratic dispersion relation and illustrate the method in a simple instance. This is joint work with G.M. Graf, G.B. Lesovik and A.V. Lebedev.