  A simple theory of the detected current I(t) flowing through charge qubits --
quantum dots -- is proposed in terms of standard continuous measurement theory.
Applied to a double dot, our formalism easily confirms previous results on
quantum Zeno effect, driven by growing ammeter performance gamma. Due to the
transparent formalism, we can calculate the exact fluctuation spectrum S(omega)
of the detected current, containing a significant Lorentzian peak near the Rabi
frequency of the double dot.
