Invariance of quantum correlations under local channel for a bipartite quantum state

We show that the quantum discord and the measurement induced non-locality (MiN) in a bipartite quantum state is invariant under the action of a local quantum channel if and only if the channel is invertible. In particular, these quantities are invariant under a local unitary channel.Comment: 4 pages, no figures, proof of theorm 2 modifie

Tight lower bound to the geometric measure of quantum discord

Dakic, Vedral and Brukner [Physical Review Letters \tf{105},190502 (2010)] gave a geometric measure of quantum discord in a bipartite quantum state as the distance of the state from the closest classical quantum (or zero discord) state and derived an explicit formula for a two qubit state. Further, S.Luo and S.Fu [Physical Review A \tf{82}, 034302 (2010)] obtained a generic form of this geometric measure for a general bipartite state and established a lower bound. In this brief report we obtain a rigorous lower bound to the geometric measure of quantum discord in a general bipartite state which dominates that obtained by S.Luo and S.Fu.Comment: 10 pages,2 figures. In the previous versions, a constraint was ignored while optimizing the second term in Eq.(5), in which case, only a lower bound on the geometric discord can be obtained. The title is also consequently changed. Accepted in Phys.Rev.

Entanglement Capacity of Nonlocal Hamiltonians : A Geometric Approach

We develop a geometric approach to quantify the capability of creating entanglement for a general physical interaction acting on two qubits. We use the entanglement measure proposed by us for $N$-qubit pure states (PRA \textbf{77}, 062334 (2008)). Our procedure reproduces the earlier results (PRL \textbf{87}, 137901 (2001)). The geometric method has the distinct advantage that it gives an experimental way to monitor the process of optimizing entanglement production.Comment: 8 pages, 1 figure

PHYTOCHEMICAL, ANTI-INFLAMMATORY, ANTIOXIDANT, CYTOTOXIC AND ANTIBACTERIAL STUDY OF CAPPARIS CARTILAGINEA DECNEFROM YEMEN

Objective: To investigate phytochemicals and biological activities of Capparis cartilaginea extracts.Methods: The methanolic extracts of leaves, stem and twigs of C. cartilaginea were screened for their phytochemicals. The essential oil of the leaves was hydrodistilled by a Clevenger apparatus and analyzed by gas chromatography-mass spectrometry (GC-MS). The leaves extract of C. cartilaginea was evaluated for its anti-inflammatory effect, using formalin-induced paw edema. The leaves, stem and twig extracts were assessed for their antioxidant activity, using free radical scavenging assay, cytotoxic activity, using 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and antibacterial activity, using the microdilution method.Results: All extracts of C. cartilaginea contained alkaloids, carbohydrates, protein, coumarin, phytosterols, bitter principles, phenols and tannins. The essential oil of the leaves was mainly composed of isopropyl isothiocyanate (69.4%), butane,1-isothiocyanate (26.97%) and isobutyl isothiocyanate (3.26%). The leaves extract at doses of 200 and 400 mg/kg, significantly inhibited paw edema at the 3rd h (49.1%, 54.0%, respectively) and this effect was comparable to that of diclofenac (58.87%). The leaves extract showed the highest antioxidant activity with IC50 value of 91.71 µg/ml. The twigs extract exhibited the highest cytotoxic activity against human lung carcinoma (A549) with IC50 of 57.5 µg/ml. The leaves and stem extracts exhibited antibacterial activity against Staphylococcus aureus with minimum inhibitory concentration (MIC) of 5.0 mg/ml. Conclusion: The leaves extract of C. cartilaginea is a potential source of bioactive compounds that could have a role in anti-inflammation. Twigs extract of the C. cartilaginea possesses a potential cytotoxic effect on human lung cell line