110,419 research outputs found
Exploring Quantum Phase Transitions with a Novel Sublattice Entanglement Scenario
We introduce a new measure called reduced entropy of sublattice to quantify
entanglement in spin, electron and boson systems. By analyzing this quantity,
we reveal an intriguing connection between quantum entanglement and quantum
phase transitions in various strongly correlated systems: the local extremes of
reduced entropy and its first derivative as functions of the coupling constant
coincide respectively with the first and second order transition points. Exact
numerical studies merely for small lattices reproduce several well-known
results, demonstrating that our scenario is quite promising for exploring
quantum phase transitions.Comment: 4 pages, 4 figure
Elastic Wave Scattering and Dynamic Stress Concentrations in Stretching Thick Plates with Two Cutouts by Using the Refined Dynamic Theory
Based on the refined dynamic equation of stretching plates, the elastic tension–compression wave scattering and dynamic stress concentrations in the thick plate with two cutouts are studied. In view of the problem that the shear stress is automatically satisfied under the free boundary condition, the generalized stress of the first-order vanishing moment of shear stress is considered. The numerical results indicate that, as the cutout is thick, the maximum value of the dynamic stress factor obtained using the refined dynamic theory is 19% higher than that from the solution of plane stress problems of elastic dynamics
Magneto-infrared spectroscopy of Landau levels and Zeeman splitting of three-dimensional massless Dirac Fermions in ZrTe
We present a magneto-infrared spectroscopy study on a newly identified
three-dimensional (3D) Dirac semimetal ZrTe. We observe clear transitions
between Landau levels and their further splitting under magnetic field. Both
the sequence of transitions and their field dependence follow quantitatively
the relation expected for 3D \emph{massless} Dirac fermions. The measurement
also reveals an exceptionally low magnetic field needed to drive the compound
into its quantum limit, demonstrating that ZrTe is an extremely clean
system and ideal platform for studying 3D Dirac fermions. The splitting of the
Landau levels provides a direct and bulk spectroscopic evidence that a
relatively weak magnetic field can produce a sizeable Zeeman effect on the 3D
Dirac fermions, which lifts the spin degeneracy of Landau levels. Our analysis
indicates that the compound evolves from a Dirac semimetal into a topological
line-node semimetal under current magnetic field configuration.Comment: Editors' Suggestio
Spectroscopic Analysis of an EIT Wave/Dimming Observed by Hinode/EIS
EIT waves are a wavelike phenomenon propagating outward from the coronal mass
ejection (CME) source region, with expanding dimmings following behind. We
present a spectroscopic study of an EIT wave/dimming event observed by
Hinode/EIS. Although the identification of the wave front is somewhat affected
by the pre-existing loop structures, the expanding dimming is well defined. We
investigate the line intensity, width, and Doppler velocity for 4 EUV lines. In
addition to the significant blue shift implying plasma outflows in the dimming
region as revealed in previous studies, we find that the widths of all the 4
spectral lines increase at the outer edge of the dimmings. We illustrate that
this feature can be well explained by the field line stretching model, which
claims that EIT waves are apparently moving brightenings that are generated by
the successive stretching of the closed field lines.Comment: 11 pages, 7 figure
Identification of the relationship between Chinese Adiantum reniforme var. sinense and Canary Adiantum reniforme
© 2014 Wang et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated
Entanglement and Quantum Phase Transition in Low Dimensional Spin Systems
Entanglement of the ground states in and dimerized Heisenberg spin
chains as well as in a two-leg spin ladder is analyzed by using the spin-spin
concurrence and the entanglement entropy between a selected sublattice of spins
and the rest of the system. In particular, we reveal that quantum phase
transition points/boundaries may be identified based on the analysis on the
local extreme of this entanglement entropy, which is illustrated to be superior
over the concurrence scenario and may enable us to explore quantum phase
transitions in many other systems including higher dimensional ones.Comment: 4 pages, 4 figure
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