Application Of Weak Measurement In Quantum Information Processing

In the process of quantum communication and information processing,the quantum system inevitably interacts with the surrounding environment.For example,in the cavity QED system,quantum decoherence or quantum dissipation happens in the controlled atoms coupled with the field environment.It will hinder the realization of the large-scale quantum information processing.This thesis focuses on the controlled atoms in optical cavity.The structured opitica-field environments are reasonably taken into account.We study the effects of the weak measurement on the quantum network communication and measurement precision of quantum parameters.The research work mainly includes the following three aspects:Firstly,we propose a quantum information processing scheme based on quantum demultiplexer.It can achieve quantum information from arbitrary output.This scheme considers the light-field environment with the characteristic of amplitude channel.And we study the protection of quantum network communication by a generalized local measurement.Generalized local measurement is a generalized form of weak measurement.We find that generalized local measurement is beneficial to improve the transmission efficiency and quantum parameter estimation accuracy of quantum information.Then,we proposed two kinds of quantum parameter measurement schemes based on weak measurement: parallel parameterized scheme and sequential parameterized.It is found that the parameter estimation accuracy can achieve Heisenberg limit in sequential parameterized.And the feasibility of this scheme with weak measurement is very high.With the consideration of structured amplitude-damping light-field environments,we analyze two kinds of the optimized schemes based on the weak measurements.Finally,the effect of weak measurement on the accelerated cavity QED system is discussed.In the non-inertial reference,the quantum dynamical evolution of the accelerated cavity QED system can be described by the Unruh channel which demonstrates the Unruh effect.When there exists quantum correlation between a stationary cavity QED system and the acceleration quantum system,the weak measurement is reasonably applied on the stationary system.It is found that the weak measurement contributes to suppress the attenuation of measurement precision and quantum correlation induced by Unruh effect.To some extent,the quantum information is protected by weak measurement.