  Destructive interference of single-electron tunneling between three quantum
dots can trap an electron in a coherent superposition of charge on two of the
dots. Coupling to external charges causes decoherence of this superposition,
and in the presence of a large bias voltage each decoherence event transfers a
certain number of electrons through the device. We calculate the counting
statistics of the transferred charges, finding a crossover from sub-Poissonian
to super-Poissonian statistics with increasing ratio of tunnel and decoherence
rates.
