  In a mesoscopic system, under zero bias voltage, a finite charge is
transferred by quantum adiabatic pumping by adiabatically and periodically
changing two or more control parameters. We obtained expressions for the pumped
charge for a ring of three quantum dots (QDs) by choosing the magnetic flux
penetrating the ring as one of the control parameters. We found that the pumped
charge shows a steplike behavior with respect to the variance of the flux. The
value of the step heights is not universal but depends on the trajectory of the
control parameters. We discuss the physical origin of this behavior on the
basis of the Fano resonant condition of the ring.
