Optimal superconducting hybrid machine

Optimal engine performances can be accomplished by quantum effects. Here we explore two routes toward ideal engines, namely (1) quantum systems that operate as hybrid machines being able to perform more than one useful task and (2) the suppression of fluctuations in doing such tasks. For classical devices, the absence of fluctuations is conditioned by a high entropy production, as dictates the thermodynamic uncertainty relations. Here we generalize such relations for multiterminal conductors that operate as hybrid thermal machines. These relations are overcome in quantum conductors as we show for a double quantum dot contacted to normal metals and a reservoir being a generator of entangled Cooper pairs.