  Employing the Lanczos algorithm in combination with a kernel polynomial
moment expansion (KPM) and the maximum entropy method (MEM), we show a way of
calculating charge and spin excitations in the Holstein t-J model, including
the full quantum nature of phonons. To analyze polaron band formation we
evaluate the hole spectral function for a wide range of electron-phonon
coupling strengths. For the first time, we present results for the optical
conductivity of the 2D Holstein t-J model.
