Spectral functions of the quantum dot coupled to normal and/or superconducting leads

We study the spectrum of the quantum dot coupled to two external leads, whi ch may be normal and/or superconducting. The dot is described by the Anders on-Hubbard impurity model in the infinity U limit. The impurity spectral fu nction shows complex behavior depending on the temperature and the state of the leads. For normal leads and at low temperature we observe the appearan ce of the Kondo resonance, while for BCS-like superconducting leads the bou nd states emerge due to absence of low energy excitations in the leads.