Study On The Thermodynamics Of Quantum Otto Engines Working With Interacting Spins

In this thesis,a quantum Otto engine with multiple spin particles as working substance is investigated in the framework of stochastic thermodynamics.For a complete cycle engine,the time-varying power fluctuation and average power are explicitly derived.The efficiency under maximum power was obtained by optimizing external control parameters.The first chapter introduces the relevant thermodynamic history and theory knowledge involved in this study,and analyzes the relevant research background,which provides a complete theoretical guidance for our research.In chapter 2,we propose a quantum Otto heat engine with two interacting spin particles as working matter,and analyze the thermodynamic quantities in the system.Analytical expressions of power,efficiency and power fluctuation are derived by using the constraints of stochastic master equations and cycle conditions.We find that the interaction between particles can increase efficiency,but at the cost of improving power fluctuations.In chapter 3,we optimize the external control parameter to obtain the efficiency under the maximum power,which is found to be independent of inter-particle interaction.In the linear response regime,the efficiency at maximum power is close to the Curzon-Ahlborn(CA)efficiency,thereby showing that they share the same universality.Such universal behavior is further verified by minimizing irreversible entropy production and the engine under consideration is found to be mapped onto the low-dissipation model.Finally,we briefly discuss the entanglement for this working system which is extend to the case of three spins.The thesis is concluded in a final discussion in chapter 4.The limitations of this thesis that hinder the present study are given,and some examples are given to illustrate interesting topics that deserved to be studied in future.