## Phase-dependent current-current correlations

### Markku Stenberg

Laboratory of Physics, Helsinki University of Technology

**Friday, 20 April 2007, 13:15**

Seminar room F

**Abstract**:

Current fluctuations provide information on the transport process which
is not contained in the conductance. For example the effective charge
*q_eff* describing shot noise yields information on the charge
transferred and also on the energy-dependent correlations between charge
transfers. We study nonequilibrium noise correlations in diffusive
normal-superconducting structures in the presence of a supercurrent. We
adopt the full counting statistic approach and present a parametrization
for the quasiclassical Green's function in the first order of the
counting field χ. This we employ to obtain the voltage
and phase dependence of cross and autocorrelations and to describe the
role played by the setup geometry. We find that the low-voltage behavior
of *q_eff* is a result of a competition between anticorrelation of
Andreev pairs due to proximity effect and the depression of the local
density of states. Furthermore, we show that the noise correlations are
independent of the sign of the supercurrent.