  In order to investigate the effects of interference and interaction in
adiabatic pumping, we consider an Aharonov-Bohm (AB) interferometer with a
quantum dot embedded either in one or in both arms. We employ a real-time
formalism and we perform an expansion both in the tunnel-coupling strengths
between dot and leads and in the pumping frequency, taking into account the
Coulomb interaction non perturbatively. We find that pumping in a single-dot AB
interferometer has a peristaltic but phase-coherent character. In a double-dot
AB interferometer, we find a pumping mechanism that relies purely on quantum
mechanical interference and has no classical counterpart.
