Beyond the Entanglement of Qubit Pairs in Multipartite Systems

What can we learn about the entanglement of a multipartite system and residual correlations beyond two-tangle if we have access only to two-qubits at a time? Algebraic analysis of two-qubit marginal states of a multiqubit system in a pure state yields monogamy constraints at different levels on distribution of entanglement between sub-systems. Monogamy constraints, reported in this letter, are relations between well known entanglement measures that is one-tangle, two-tangles and three-tangles of an N-qubit pure state. Criterion to detect multipartite entanglement of an N-qubit pure state is also reported