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The global geometric entanglement (GE) is studied in the context of newly developed tensor network algorithms for finite systems. For onedimensional quantum spin systems it is found that, at criticality, the leading finite-size correction to the global GE per site behaves as b/n, where n is the size of the system and b a given coefficient. Our conclusion is based on the computation of the GE per spin for the quantum Ising model in a transverse magnetic field and for the spin-1/2 XXZ model. We also discuss the possibility of coefficient b being universal. [ABSTRACT FROM AUTHOR]

The high-pressure behavior of solid hydrogen has been investigated by in situ Raman spectroscopy upon compression to 300 GPa at ambient temperature. The hydrogen vibron frequency begins to decrease after it initially increases with pressure up to 38 GPa. This softening behavior suggests the weakening of the intramolecular bond and the increased intermolecular interactions. Above 237 GPa, the vibron frequency softens very rapidly with pressure at a much higher rate than that of phase III, corresponding to transformation from phase III into phase IV. The phase transition sequence has been confirmed from phase I to phase III and then to phase IV at 208 and 237 GPa, respectively. Previous theoretical calculations lead to the proposal of an energetically favorable monoclinic C2/c structure for phase III and orthorhombic Pbcn structure for phase IV. Up to 304 GPa, solid hydrogen is not yet an alkali metal since the sample is still transparent. [ABSTRACT FROM AUTHOR]

It is shown that the fidelity, a basic notion of quantum information science, may be used to characterize quantum phase transitions, regardless of what type of internal order is present in quantum many-body states. The equivalence between the existence of an order parameter and the orthogonality of different ground-state wavefunctions for a system undergoing a quantum phase transition is used to justify the introduction of the notions of irrelevant and relevant information as the counterparts of fluctuations and orders in the conventional description. The irrelevant and relevant information are quantified, which allows us to identify unstable and stable fixed points (in the sense of renormalization group theory) for quantum spin chains. [ABSTRACT FROM AUTHOR]