  Statistical properties of the electron transport flowing through
nanostructures are strongly influenced by the interactions, geometry of the
system and/or by type of the external electrodes. These factors affect not only
the average current induced in the system but also contribute to fluctuations
in the flux of charges and their correlations. Due to possible applications of
the hybrid nano-systems, containing one or more superconducting electrodes, a
detailed understanding of the flow of charge and its fluctuations seems to be
of primary importance. Coulomb repulsion between electrons usually strongly
affect the current-current correlation function. In this work we study the
correlations in the charge flow through such interacting quantum dot contacted
to one superconducting and two normal electrodes. This set-up allows for
analysis of the Andreev scattering events in the correlations of currents
flowing between external electrodes and, in particular, gives access to
cross-correlations between currents from/to different normal electrodes. Our
approach relies on the master equation technique, which properly captures the
Coulomb interactions. We study the finite frequency correlations and find the
relaxation processes, related to the high frequency charge and low frequency
polarisation fluctuations. The multiterminal structure of here studied single
electron device allows to analyze a competition between the intra- and
inter-channel correlations. In the appropriate limit of the interacting quantum
dot embedded between two normal electrodes our calculations quantitatively
describe the recent experimental data on the frequency dependent correlations.
This shows a promising potential of the method for description of the hybrid
systems with superconducting electrode(s).
