  We measure the shot noise of a quantum point-contact using a capacitively
coupled InAs double quantum dot as an on-chip sensor. Our measurement signals
are the (bidirectional) interdot electronic tunneling rates which are
determined by means of time-resolved charge sensing. The detector frequency is
set by the relative detuning of the energy levels in the two dots. For nonzero
detuning, the noise in the quantum point contact generates inelastic tunneling
in the double dot and thus causes an increase in the interdot tunneling rate.
Conservation of spectral weight in the dots implies that this increase must be
compensated by a decrease in the rate close to zero detuning, which is
quantitatively confirmed in our experiment.
