Optimization of a three-terminal non-linear heat nano-engine
  Charge and heat transport in nano-structures is dominated by non-equilibrium effects which strongly influence their behaviour. These effects are studied in a setup consisting of three external leads, one of which is considered as a heat reservoir and is tunnel-coupled to two cold electrodes via two independently controlled quantum dots. The energy flow from the hot electrode together with energy filtering provided by quantum dots leads to a voltage bias between the cold electrodes. The heat and charge currents in the device effectively flow in mutually perpendicular directions, allowing for their independent control. The non-equilibrium screening changes the values of the system parameters needed for its optimal performance but leaves the maximal output power and efficiency unchanged. Our results are important from the theoretical point of view as well as for the practical implementation and the control of the proposed heat engine. 
Barbara Szukiewicz, Ulrich Eckern, and Karol I. Wysokinski
cond-mat.mes-hall