Tighter Monogamy Relations In Multiqubit Systems

As an important physical resourse quantum entanglement plays an important role in quantum information processing.At present,there already have been good results about the description of entanglement in the two-qubit systems.The characterization of the distribution of entanglement in the multipartite quantum systems becomes an attractive quantum entanglement theory.Entanglement monogamy is an important property for multipartite quantum system and it can be used to describe the entanglement structure in multipartite quantum system.On the basis of predecessors,using our new inequality we mainly obtain the tighter monogamy relations about concurrence,entanglement of formation,negativity,Tsallis-q entanglement,R(?)nyi-? entanglement in multiqubit quantum systems.The full text is divided into three chapters.The first chapter is preparatory knowledge,which are the basic knowledge and concepts used in the thesis.In the second chapter,we obtain the tighter monogamy relationship of concurrence of multiqubit systems when the parameters satisfy certain conditions in the inequality we present.By the functional relationship between entanglement of formation and concurrence,the relationship between negativity and concurrence for any pure state with Schmidt rank less than 2,the functional relationship between Tsallis-q entanglement and concurrence,and the relationship between R(?)nyi-? entanglement and concurrence,we derive the tighter monogamy relationships of entanglement of formation,negativity,Tsallis-q entanglement,R(?)nyi-? entanglement of multiqubit systems.In the third chapter,based on the relationship between concurrence of assistance and concurrence,and the relationship between negativity of assistance and concurrence of the W-class state,we obtain the tighter monogamy of concurrence of assistance and negativity of assistance of the W-class state respectively.