History Matching Using Principal Component Analysis

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Genuine Four Tangle for Four Qubit States

We report a four qubit polynomial invariant that quantifies genuine four-body correlations. The four qubit invariants are obtained from transformation properties of three qubit invariants under a local unitary on the fourth qubit.Comment: 03 pages, This short communication is a contribution to the proceedings of QCMC 2012 held in Vienna, Austria, July 30th to August 3rd 201

Unitary Invariants and Classification of Four-Qubit States via Negativity Fonts

Local unitary invariance and the notion of negativity fonts are used as the principle tools to construct four qubit invariants of degree 8, 12, and 24. A degree 8 polynomial invariant that is non-zero on pure four qubit states with four-body correlations and zero on all other states, is identified. Classification of four qubit states into seven major classes, using criterion based on the nature of correlations, is discussed.Comment: 12 pages, revtex, Eq. 26 and other Typos correcte

Two-way and three-way negativities of three qubit entangled states

We propose to quantify three qubit entanglement using global negativity along with K-way negativities, where K=2 and 3. K-way partial transpose with respect to a subsystem is defined so as to shift the focus to K-way coherences of the composite system instead of K subsystems of the composite system. While genuine tripartite entanglement of three qubit composite system is generated by 3-way coherences, tripartite entanglement can be present due to 2-way coherences as well.Comment: 07 pages, 04 figures, References added, text revised and figures revise