The Dynamics Of Quantum Correlation And Fisher Information In The Hierarchical Environment

Quantum systems have fascinating properties that do not exist in classical systems.These characteristics can be characterized and quantified from different perspectives of quantum correlation,such as Bell non-locality,quantum entanglement,quantum dicord,and quantum steering.The feature of quantum correlation not only has theoretical significance,but also can be developed and utilized as an indispensable physical resource in emerging technologies such as quantum communication and quantum metrology.In experimental researches,in order to extract the information from quantum state,people usually need to perform quantum measurements.These quantum measurement operating technologies naturally lead to the emergency of quantum Fisher information.In the quantum field,fisher information has a richer structure and more potential that the classical world does not have.Especially,in the research of quantum detection and parameter estimation,quantum fisher information plays a vital role.Because the inevitably interaction between system and the surrounding environment can make the quantum coherence decay rapidly,resulting in the loss of quantum information,which has become a major obstacle to the development of new quantum technologies.Therefore,it is of great practical significance to study the decoherence mechanism of the system,to find out possible decoherence sources,and to find effective methods to eliminate them,or to take effective schemes to suppress the decoherence as much as possible.The entanglement system of three-qubit in the hierarchical environment was discussed from the following aspects:Firstly,based on three independent qubit systems coupled with their respective cascade cavities,the influences of strong and weak coupling strength g(the coupling strength between the qubit and the cavity),the cavity-cavity coupling strength Ω and the cavity dissipation rate Γ1 on negativity,Bell non-locality and entangled witnesses were investigated in detail.The results show that both Bell non-locality and the entanglement quantified by entanglement witnesses will exhibit the phenomenon of sudden death and sudden.When the cavity decay rate Γ1=0,as the cavity coupling strength increases,these three measures will experience short-term damped oscillations,after which they will reach their respective stable values,and the greater the Ω is,the greater the stable value is.At the same time,the magnitude or survival time of these three measures in the weak coupling system is always better than those in the strong weak coupling system.In addition,the existence of cavity decay rate Γ1 also has a great negative influence on quantum correlation.In order to suppress the influence of the environment on the quantum correlation,we further analyzed the effective manipulating of weak measurement and measurement reversal operations,and obtained some interesting results.Secondly,we have studied the dynamics of the quantum fisher information in the three-qubit system and the manipulating role of the filtering operation in it.The results showed that when the cavity decay rateΓ1=0 and the coupling between the cavity and the cavity is Ω=0,in the strong and weak coupling regimes,the quantum fisher information will always decay monotonously to zero after a period of time.Different from the strong coupling regime,the survival time of the quantum fisher information is longer in the weak coupling regime.When the cavity-cavity interaction exists,as the cavity coupling strength increases,the quantum fisher information reaches a stable value after a short-term damped oscillation,and the larger Ω is,the more intense the oscillation and the greater the stable value is.However,when there is dissipation in the coupled cavity,that is,Γ1≠0,the quantum fisher information will not be remained steadily.In order to suppress the loss of Fisher information caused by the destruction of quantum correlations,we introduce filtering operations.It has been shown that filtering operations can play an active role in protecting quantum fisher information.