  This paper presents a conceptual design for quantum heat machines using a
pair of coupled double quantum dots (DQDs), each DQD with an excess electron to
interact, as an working substance. We define a compression ratio as the ratio
between the Coulomb potentials which describes the interaction between the
electrons during the isochoric processes of the quantum Otto cycle and then we
analyse the arising of different regimes of operations of our thermal machine.
We also show how we can achieve truly quantum effects, escaping the classical
results expected for a quantum Otto engine, when considering the effects due to
a quantum tunnelling of a single electron between each individual DQD.
