  Periodically driven quantum dots can act as counterparts of cyclic thermal
machines at the nanoscale. In the slow-driving regime of geometric pumping,
such machines have been shown to operate in analogy to a Carnot cycle. For
larger driving frequencies, which are required in order to increase the cooling
power, the efficiency of the operation decreases. Up to which frequency a
close-to-optimal performance is still possible depends on the magnitude and
sign of on-site electron-electron interaction. Extending our previous detailed
study on cyclic quantum-dot refrigerators [Phys. Rev. B 106, 035405 (2022)], we
here find that the optimal cooling power remains constant up to weak
interaction strength compared to the cold-bath temperature. By contrast, the
work cost depends on the interaction via the dot's charge relaxation rate, as
the latter sets the typical driving frequency for the onset of non-geometric
pumping contributions.
