  We study adiabatic quantum pumps on time scales that are short relative to
the cycle of the pump. In this regime the pump is characterized by the matrix
of energy shift which we introduce as the dual to Wigner's time delay. The
energy shift determines the charge transport, the dissipation, the noise and
the entropy production. We prove a general lower bound on dissipation in a
quantum channel and define optimal pumps as those that saturate the bound. We
give a geometric characterization of optimal pumps and show that they are
noiseless and transport integral charge in a cycle. Finally we discuss an
example of an optimal pump related to the Hall effect.
