Research On Quantum Properties In Quantum Refrigerator

Quantum thermodynamics,which investigates physical phenomena at the intersection of quantum mechanics and classical thermodynamics,is an interdisciplinary subject and by now a well developed field.Quantum machine provides a good platform for people to study quantum thermodynamics.It is very meaningful to study the quantum properties of the quantum machine and to compare the properties with the classical heat machine.This study not only helps us to study the relationship between quantum mechanics and thermodynamics,but also helps to study quantum decoherence.In addition,it can also well reflect the differences between quantum mechanics and thermodynamics,so that we can better understand the transition problem in thermodynamics.In this thesis,we will study the quantum refrigerator model.Explore some problems related to thermodynamics and quantum thermodynamics.In the second chapter,we give a brief introduction to some basic physical concepts in this thesis,such as qubit,density matrix,which lay a theoretical foundation for the later application.In the third chapter,we introduce the quantum refrigerator model to be studied.It includes two different interactions,namely the strong interaction between two qubits and the weak interaction between three qubits.Based on the method of the master equation in the quantum open system,the physical quantities(such as the heat flow,the efficiency)and the coherence in the steady state of the refrigerator model are analyzed and calculated.Through numerical analysis,when the refrigerator system meets the positive work conditions,we find that the partial quantum properties of the system are beneficial to refrigeration,but it is not beneficial to the efficiency.In the fourth chapter,we present a perturbative method to solve the steadystate solutions of linear local master equations,which are demonstrated by two simple models.The solving process shows the stationary state as the result of competition between incoherent operations and the unitary creating quantum coherence,and consequently relate quantum coherence with thermodynamic consistency.