  Three-terminal coherent conductors are able to perform as quantum
thermocouples when the heat absorbed from one terminal is transformed into
useful power in the other two. Allowing for a phase coherent coupling to the
heat source, we introduce a way to control and improve the thermoelectric
response via quantum interference. A simple setup composed of a scanning probe
between two resonant tunneling regions is proposed that achieves better
performance than incoherent analogs by enhancing the generated power and
efficiency, and reducing the output current noise.
