Quantum Thermalization And Quantum Entanglement In Nonequilibrium Coupled Light-atom Systems

The Jaynes-Cummings(JC)model,which describes the interaction of a two-level system(TLS)with a single-mode bosonic field,is considered as one of the most important and basic models in quantum optics.The JC model not only has important physical significance in various branches of modern physics such as atomic physics,quantum optics,and solid-state physics,but also has wide applications prospect in frontier quantum technologies including quantum control,quantum precision measurement,and quantum information processing.So far,many important physical effects and phenomena have been observed in the JC model,such as the quantization of electromagnetic fields,the vacuum Rabi splitting,and the collapse and revival of the inversion population of the TLS.All the phenomena observed are subjected to the influence of the dissipations because quantum systems are inevitably coupled to their environments.In particular,many interesting observations are based on the steady state of the JC system.Therefore,quantum statistical physics such as quantum thermalization and thermal entanglement are significant research topics in the open JC model.In this paper,based on two coupling modes of JC model and environment,we study the quantum thermalization and thermal entanglement of JC model in equilibrium and non-equilibrium open systems.This thesis is organized as follows:In the first chapter,we briefly introduces the research background and significance of JC model,and then solve the eigen system of quantum JC model and Rabi model.We also introduces quantum thermalization and the quanta of entanglement.In the second chapter,we introduce the open JC model Hamiltonian,we will also derive a microscopic master equation to describe the evolution of the JC model in both individual heat bath and a common heat bath cases.We compare the dynamics of the JC system when it is described by the phenomenological quantum master equation and the dressed-state master equations in the individual heat bath and common heat bath cases.In the third chapter,based on the master equation obtained in the second chapter,the temperature of each two energy levels of the JC model is calculated to judge the thermalization of the JC model under various parameters of individual heat baths and common heat bath.The results show that in the case of IHB,the JC model can only be thermalized when the two heat baths have the same temperature or when the coupling of the JC system to one of the two baths is turned off,while the JC system can be thermalized in the common heat-bath case irrespective of the bath temperature and the system-bath coupling strengths.We also study the thermal entanglement in this system.We find and prove a counterintuitive phenomenon of vanishing thermal entanglement in the JC system.The fourth chapter provides a summary and a prospect of this thesis.