Cooling by Coulomb Heat Drag Based on Three Coupled Quantum Dots

We establish a model for a four-terminal thermoelectric system,based on three coupled quantum dots,which consists of a left/right electron reservoir(the source and the drain),two thermal reservoirs and three coupled quantum dots.Based on the master equation theory,we derive the expressions of the electron current and heat flow among the three quantum dots and the corresponding reservoir.We show that the source can be cooled by passing a thermal current between the two thermal reservoirs,with no net heat exchange between the thermal reservoirs and the electron reservoirs.This effect is called the Coulomb heat drag effect.Then,we define the coefficient of performance(COP) and the cooling power.The influence of the main system parameters,such as charging energy,energy level,and temperature,on the performance of the four-terminal thermoelectric system is analyzed in detail.By choosing appropriate parameters one can obtain the maximum cooling power and the corresponding COP.Finally,we also show that the Maxwell demon effect can be realized by using nonequilibrium thermal reservoirs in our four-terminal thermoelectric system.