  We study two capacitively coupled double quantum dots focusing on the regime
in which one double dot is strongly biased, while no voltage is applied to the
other. Then the latter experiences an effective driving force which induces a
ratchet current, i.e., a dc current in the absence of a bias voltage. Its
current noise is investigated with a quantum master equation in terms of the
full-counting statistics. This reveals, that whenever the ratchet current is
large, it also exhibits some features of a Poissonian process. By eliminating
the drive circuit, we obtain a reduced master equation which provides
analytical results for the Fano factor.
