  Interference effects in quantum dots between different transport channels can
lead to a strong suppression of conductance, which cuts like a canyon through
the common conductance plot [Phys. Rev. Lett. 104, 186804 (2010)]. In the
present work, we consider the thermoelectric transport properties of the canyon
of conductance suppression using the second-order von Neumann approach. We
observe a characteristic signal for the zeros of the thermopower. This
demonstrates that thermoelectric measurements are an interesting complimentary
tool to study complex phenomena for transport through confined systems.
