  We investigate theoretically a novel type of high frequency quantum detector
based on the mesoscopic capacitor recently realized by Gabelli et al., [Science
{\bf 313}, 499 (2006)], which consists of a quantum dot connected via a single
channel quantum point contact to a single lead. We show that the state of a
double quantum dot charge qubit capacitively coupled to this detector can be
read out in the GHz frequency regime with near quantum limited efficiency. To
leading order, the quantum efficiency is found to be universal owing to the
universality of the charge relaxation resistance of the mesoscopic capacitor.
