Environmental noise usually hinders the efficiency of charge transport
through coherent quantum systems; an exception is dephasing-assisted transport
(DAT). We show that linear triple quantum dots in a transport configuration and
subjected to pure dephasing exhibit DAT if the coupling to the drain reservoir
exceeds a threshold. DAT occurs for arbitrarily weak dephasing and the
enhancement can be directly controlled by the coupling to the drain. Moreover,
for specific settings, the enhanced current is accompanied by a reduction in
relative shot noise. We identify the quantum Zeno effect and long-distance
tunnelling as underlying dynamical processes involved in dephasing-assisted and
-suppressed transport. Our analytical results are obtained by using the density
matrix formalism and the characteristic polynomial approach to full counting
statistics.Comment: To appear in New Journal of Physics, 20 pages, 5 figure
