Study On Dynamics Of Quantum Coherence In Optical Hybrid Systems

In the field of optical quantum information,measurements of quantum coherence becomes a hot issue of the present optical frontiers.As one important kind of quantum resources,quantum coherence has been extensively applied to quantum remote communication,optical quantum computation and precise metrology based on optical controlling.Recently,optical hybrid systems have some amazing advantages of preparation,manipulation and integration.In this thesis,we take into account the optical hybrid systems with atoms coupled to optical fields.The atom-microcavity system and non-Hermitian atoms controlled by optical fields can be constructed.The spatial distribution of multipartite quantum coherence and evolution of quantum temporal coherence are also investigated.The dissipation mechanism of quantum coherence can be explored in the optical hybrid systems by means of quantum channels which can simulate the constructed optical environments.The main contents of the thesis include three aspects:Firstly,the atom-microcavity system with asymmetric interactions is studied.We analyze the impacts of asymmetric interactions on the distribution of three-body quantum coherence and its decoherence by the optical manipulation.It is found that the dynamics of multipartite quantum coherence is closely related to the types of initial states.When the initial state is chosen to be a Werner-like entangled state,the total coherence measure is equal to the sum of all two-body quantum coherence.This kind of coherence additivity can be violated under the influence of optical noise environments.Secondly,the non-Hermitian atomic system with parity-time(PT)symmetry can be constructed.The effective two-level optical hybrid system is obtained by the optical control of a(43)-type three-level atom.When the adjustable optical paramters are varied,the system takes on two kinds of phases including the PT phase and PT-broken one.It is found that when the system with real energy values is in PT symmetric phase,the quantum coherence has the largest value.We realize the control of quantum coherence in the non-Hermitian optical hybrid system by applying the atomic beam splitter.The decoherence is also investigated.Finally,the dynamics of quantum temporal coherence is studied based on the time correlation functions.The inequality of quantum temporal coherence is set up in the non-Hermitian optical hybrid system by the high-order time correlation functions.The squeezed optical environment is simulated by a squeezing generalized amplitude damping channel.When the system with PT symmetry is subjected to the squeezed optical environment,the evolution of quantum temporal coherence depends on the squeezing parameter and environmental temperatures.These conclusions can provide the research basis for the realization of quantum coherence measure,quantum communication and computation based on the optical hybrid systems.