Interconversion And Manipulation Between Quantum Coherence And Quantum Correlations In Multipartite Systems

Quantum resource has obvious advantages in communication security and computation speedup over its classical counterpart in quantum information processing.Quantum coherence is a kind of important resource in quantum systems,which plays a key role in quantum computation.Beyond quantum coherence,another iconic quantum resource is quantum correlation in bipartite or multipartite systems.It is well known that quantum entanglement is a typical quantum correlation,but there are other types of quantum correlations without entanglement.That is to say,quantum correlation is more general than quantum entanglement.Quantum discord is a prominent measure to characterize quantum correlation.In particular,the distance-based measure of discord is easy to generalize to the case of many body systems.In recent years,the study of conversion between different kinds of quantum resources under some specific operations has been paid great attention.It is very meaningful because quantum resource conversion allows us to measure one kind of resource with another and construct a unified theory of quantum resources.Theoretical and experimental results show that quantum coherence,quantum entanglement and quantum correlation can be interconverted under certain scenarios,and some useful constraint relations for resource conversion have been presented.So far,there are many good results in resource conversion for bipartite systems,but the corresponding results in multipartite systems are still lacking,and among which the optimal conversion needs extraordinary amounts of attention.In this thesis,we study the interconversion and manipulation between quantum coherence and quantum correlations in multipartite systems.In Chapter I,we introduce some basic concepts and measures for quantum coherence,quantum entanglement and quantum correlation.Then we review the advances in quantum resource conversion both theoretically and experimentally.In Chapter II,via the measure of relative entropy,we give the constraint relation in the process of converting quantum coherence into tripartite quantum correlation and present an optimal resource conversion scheme.Furthermore,the optimal scheme is also presented for converting tripartite quantum correlation into single-body coherence or two-body quantum correlation under local quantum incoherent operations and classical communications.The similar scheme for interconversion between quantum coherence and quantum correlations can also be generalized to N-partite systems.In Chapter ?,we study entanglement property and resource dynamics in the conversion from quantum coherence to quantum entanglement.For a multilevel coherent state,one can convert it to bipartite multilevel entangled state through an optimal conversion scheme.We show that the initial parameters of coherent state determine whether or not the output state is genuine bipartite multilevel entanglement.In addition,we prove that,under local noisy channels,coherence of single-qubit is more robust than the three-qubit entanglement converted by the optimal scheme.At the end of this thesis,we summarize our main results on resource conversion and manipulation,and make an outlook for the study in future.