The Research On Heat Transfer Characteristics Based On Few-body Quantum Small System

As the science and technology has developed,the systems that people study tend to be miniaturized,even to smaller molecular and atomic scales.Miniaturized systems like quantum dot TVs,molecular motors,quantum computers,and quantum chips have begun to appear in tons of fields such as life,science and technology,and medical treatment.The system dynamics characteristics of quantum systems such as information transmission and energy transmission will be affected by quantum effects(quantum coherence,quantum entanglement,etc.),which make quantum systems show many phenomena different from macroscopic systems.In recent years,the heat transfer and control management of quantum systems have attracted the attention of many scholars.Due to the influence of quantum effects,the heat transfer characteristics of quantum systems will become very complicated,and exhibit many phenomena that are not available in classical heat transfer,such as energy transfer from low-temperature storage to high-temperature storage.Therefore,exploring the thermal properties of quantum systems and the influence of quantum effects on heat transfer has become an important subject of current quantum physics research.Scholars have explored the heat transfer behavior of the system based on a variety of quantum system models,such as quantum spin chains,quantum dots,and multi-level systems.At present,most of the research on heat transfer mainly focuses on the influence of the internal quantum effect of the system on the heat transfer of the system.Three-body coupled quantum system is an executable quantum model in current experiments.The first research work explored the heat transfer behavior of the system when the environment carries quantum effects(such as coherence and entanglement).In the second research work,the three-qubit spin chain is used as the research system to explore the influence of the structural characteristics and coupling strength of the system on the heat transfer of the system under the local thermal environment.The following is a brief overview of the two main research work in this paper.In the first research work,we designed a heat transfer scheme based on the three-qubit system,and explored the heat transfer between the system and the target environment under the auxiliary bath.In the thermodynamics framework of the collision model,we discussed the influence of the coherence strength,coherence phase and coupling strength of the aux-iliary bath on the thermal current and the thermal function of the system.Analyzed the influence of coupling between subsystems and quantum measurement operations on the heat transfer of the system.The results show that:1)Quantum coherence could be used as useful thermal control resources;2)Under a specific coherence strength or phase,the thermal current could be amplified,reduced and reversed by adjusting a single coupling parameter(the coupling of the system and the auxiliary bath);3)Under the coherent auxiliary bath,the quantum system acts as a multi-functional quantum device with thermal amplification,thermal suppression,cooling and thermal switching functions.The second research work,based on the three-qubit spin chain model with different coupling modes,studied the heat transfer behavior of the spin chain system coupled with two independent thermal baths.The details include:1)The general master equation for the evolution of the spin chain system is deduced;2)Discussed the heat transfer characteristics of XXX,XXZ,XYZ type(the coupling strength in the z direction is zero and not zero)three-qubit spin chain;3)The influence of the coupling parameters in the directions of x,y and z and the temperature difference on the heat transfer of the spin chain are analyzed.The research found that:1)Under the interaction of energy conservation(XXX and XXZ coupling model),the heat transfer of the spin chain system depends on the temperature difference of the two baths.When the temperature difference between the two storages is fixed,the lower the temperature of the low temperature bath,the greater the heat flow through the system;2)In the XXX-type coupling mode,the heat flow depends on the coupling parameters,and in the XXZ-type coupling mode,the heat flow depends on the coupling parameters of x and y direction.In these two coupling modes,the heat flow through the system is positively related to the coupling strength.When the coupling strength reaches a certain value,the heat flow flowing through the system reaches the stable maximum heat flow;3)For the XXZ-type system,when the coupling strength |?z| of the z direction is zero,the thermal current of the system is the largest;4)For the XYZ spin coupling method,the system can be used as a heat pump to heat the high temperature and low temperature bath at the same time.The greater the difference between the coupling strengths in the x and y directions,the stronger the pumping capability of the system.The research work of the paper verifies that the quantum coherence of the auxiliary bath could be used as a useful resource for the thermal regulation of the target thermal bath,and provide a new idea for the design of non-equilibrium quantum bath thermal management devices.Through the study of the heat transfer characteristics of the spin chains with various coupling interactions,the different behaviors of heat transfer under different coupling modes and the direct relationship with related parameters are revealed.At the same time,it provides a certain theoretical reference for the design of heat transfer devices based on the spin chain system.