Mono-parametric quantum charge pumping: Interplay between spatial interference and photon-assisted tunneling

We analyze quantum charge pumping in an open ring with a dot embedded in one of its arms. We show that cyclic driving of the dot levels by a single parameter leads to a pumped current when a static magnetic flux is simultaneously applied to the ring. Based on the computation of the Floquet-Green's functions, we show that for low driving frequencies omega(0), the interplay between the spatial interference through the ring plus photon-assisted tunneling gives an average direct current, which is proportional to omega(2)(0). The direction of the pumped current can be reversed by changing the applied magnetic field.