Pumped current and voltage for an adiabatic quantum pump

We consider adiabatic pumping of electrons through a quantum dot. There are two ways to operate the pump: to create a dc current $Ī$ or to create a dc voltage $\overline{V}.$ We demonstrate that, for very slow pumping, $Ī$ and $\overline{V}$ are not simply related via the dc conductance G as $Ī=\overline{V}G.\mathrm{}$ For the case of a chaotic quantum dot, we consider the statistical distribution of $\overline{V}G-Ī.$ Results are presented for the limiting cases of a dot with single-channel and with multichannel point contacts.