Thermoelectric Transport In Four-terminal Quantum Dot System

Since the industrial revolution,how to transform heat into work has been the core issue.In order to understand the physical process of thermal power conversion,the theory of thermodynamics was born.The conversion of thermal energy into electrical energy can be realized by thermoelectric effect,so the research in recent years mainly focuses on the nanoscale thermoelectric devices and microscale thermoelectric transport properties.In addition to the existing research on the elastic thermoelectric transport in the mesoscopic system,more attention has been paid to the inelastic process,that is,the electron energy is not conserved in the transport process.Compared with conventional elastic thermoelectric devices,inelastic thermoelectric devices can achieve higher efficiency and greater output power.Several types of inelastic thermoelectric devices have been studied,involving electron-phonon or electron-electron interaction.This article will demonstrate the inelastic thermoelectric transport at low temperatures and discuss the key influence of electron-electron interactions.Firstly,the steady-state transport properties in various mesoscopic systems and the fundamental problems of thermal power conversion in nanoscale scale are discussed.Then a three-terminal device model with a quantum dot is introduced in detail.The heat from the third terminal can induce the source and drain to generate electricity.The intrinsic mechanism is inelastic Coulomb scattering.When the left-right inversion symmetry is destroyed,it will produce directional transport as in other quantum fields.In this process,the heat at the third end is collected to generate electrical energy across the source and drain.The innovation of this research work lies in the discovery that the Coulomb interaction between two circuits separated by an insulating layer will lead to unconventional thermoelectric effects,such as cooling by thermal current effect and Maxwell's demon effect.The cooling by thermal current effect refers to the cooling caused by the thermal current in another circuit in one circuit.The specific content is as follows:Firstly,a four-terminal four-quantum dot thermoelectric transport system is constructed,which can be regarded as two independent circuits.At the beginning,demonstrate the Coulomb resistance of each circuit with one quantum dot,propose the microscopic theory of thermoelectric transport in quantum dot system,construct the expressions of current and heat flow,study the steady-state transport through two quantum dots by master equation method,and obtain the tunneling rate.Then the case of two quantum dots in each circuit is described.The unconventional thermoelectric transport under the Coulomb drag effect is studied,and the unconventional thermoelectric energy conversion formula is obtained.Then,the cooling effect of thermal current is studied,and the cooling power and coefficient of performance are calculated.Finally,it is proved that this quantum dot system can realize Maxwell's demon without violating the second law of thermodynamics.In other words,the two electronic heat sources in the system can be used to generate electricity in the manner of Maxwell's demon,cooling low-temperature heat sources or heating high-temperature heat sources,where the working substance does not exchange any energy or particles with the two heat sources.This work reveals the role of Coulomb interaction in the non-local four terminal quantum thermoelectric transport,which is conducive to the autonomous energy saving of nano electronic devices.