We consider multipartite states of qubits and prove that their bipartite quantum entanglement, as quantified by the concurrence, satisfies a monogamy inequality conjectured by Coffman, Kundu, and Wootters. We relate this monogamy inequality to the concept of frustration of correlations in quantum spin systems.
We investigate possible generalizations of the Coffman-Kundu-Wootters monogamy inequality to four qubits, accounting for multipartite entanglement in addition to the bipartite terms. We show that the most natural extension of the inequality does not hold in general, and we describe the violations of this inequality in detail. We investigate alternative ways to extend the monogamy inequality to express a constraint on entanglement sharing valid for all four-qubit states, and perform an extensive numerical analysis of randomly generated four-qubit states to explore the properties of such extensions.
We provide a detailed proof of an analytical lower bound of entanglement quantified by concurrence for arbitrary bipartite quantum states. It is shown that though the bound does not allow one to detect bound entanglement, it is tight for some mixed states and can detect most of the free entanglement. On the other hand, it is known that the entanglement monogamy inequality proposed by Coffman, Kundu, and Wootters is, in general, not true for higher-dimensional quantum states. Inducing from the lower bound of concurrence, we find a proper form of entanglement monogamy inequality for arbitrary pure quantum states.
As the quantum entangled states are as a source for many of branches different quantum information theory, such as dense encoding,encryption and teleportation, theoretical study of any relation between the different parts of a entangled quantum state of semi-transparent. One of these relations, inequality monogamy. Although the correlation classical can be freely in the multipartite systems will be shared, the famous that quantum entanglement in this share has restrictions. This restriction on the sharing of entanglement, the famous to monogamy in the multipartite quantum systems. In terms of math, monogamy in the entanglement the first was introduced by Coffman-Kundu-Wootters (CKW) in the three qubit systems. Inequality CKW that obtained for the measure concurrence, mutually unique nature of entanglement two qubits common in the three qubit systems shows. A simple example of the monogamy property can be expressed that the amount of entanglement between A and B to add the amount of entanglement between A and C cannot be greater than the amount of entanglement between A and pair BC. The aim of this thesis reviews the types monogamy inequality defined for the various entangled measures especially measure concurrence.