  We theoretically investigate the thermoelectric properties of heat engines
based on Mach-Zehnder interferometers. The energy dependence of the
transmission amplitudes in such setups arises from a difference in the
interferometer arm lengths. Any thermoelectric response is thus of purely
quantum mechanical origin. In addition to an experimentally established
three-terminal setup, we also consider a two-terminal geometry as well as a
four-terminal setup consisting of two interferometers. We find that
Mach-Zehnder interferometers can be used as powerful and efficient heat engines
which perform well under realistic conditions.
