Title: Correlation effects in superconducting quantum dot systems,
Abstract: We study the effect of electron correlations on a system consisting of a
single-level quantum dot with local Coulomb interaction attached to two
superconducting leads. We use the single-impurity Anderson model with BCS
superconducting baths to study the interplay between the proximity induced
electron pairing and the local Coulomb interaction. We show how to solve the
model using the continuous-time hybridization-expansion quantum Monte Carlo
method. The results obtained for experimentally relevant parameters are
compared with results of self-consistent second order perturbation theory as
well as with the numerical renormalization group method.