  We present a theoretical study of the detection of the decay time scales for
a single-level quantum dot by means of a capacitively coupled sensor dot, which
acts as an electrometer. We investigate the measurement back-action on the
quantum-dot decay rates and elucidate its mechanism. We explicitly show that
the setup can be used to measure the bare quantum-dot relaxation rates by
choosing gate pulses that minimize the back-action. Interestingly, we find that
besides the charge relaxation rate, also the rate associated to the fermion
parity in the dot can be accessed with this setup.
