7,226 research outputs found
Entanglement entropy and entanglement spectrum of the Kitaev model
In this paper, we obtain an exact formula for the entanglement entropy of the
ground state and all excited states of the Kitaev model. Remarkably, the
entanglement entropy can be expressed in a simple separable form S=S_G+S_F,
with S_F the entanglement entropy of a free Majorana fermion system and S_G
that of a Z_2 gauge field. The Z_2 gauge field part contributes to the
universal "topological entanglement entropy" of the ground state while the
fermion part is responsible for the non-local entanglement carried by the Z_2
vortices (visons) in the non-Abelian phase. Our result also enables the
calculation of the entire entanglement spectrum and the more general Renyi
entropy of the Kitaev model. Based on our results we propose a new quantity to
characterize topologically ordered states--the capacity of entanglement, which
can distinguish the states with and without topologically protected gapless
entanglement spectrum.Comment: 4.0 pages + supplementary material, published version in Phys. Rev.
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Momentum polarization: an entanglement measure of topological spin and chiral central charge
Topologically ordered states are quantum states of matter with topological
ground state degeneracy and quasi-particles carrying fractional quantum numbers
and fractional statistics. The topological spin is an
important property of a topological quasi-particle, which is the Berry phase
obtained in the adiabatic self-rotation of the quasi-particle by . For
chiral topological states with robust chiral edge states, another fundamental
topological property is the edge state chiral central charge . In this paper
we propose a new approach to compute the topological spin and chiral central
charge in lattice models by defining a new quantity named as the momentum
polarization. Momentum polarization is defined on the cylinder geometry as a
universal subleading term in the average value of a "partial translation
operator". We show that the momentum polarization is a quantum entanglement
property which can be computed from the reduced density matrix, and our
analytic derivation based on edge conformal field theory shows that the
momentum polarization measures the combination of
topological spin and central charge. Numerical results are obtained for two
example systems, the non-Abelian phase of the honeycomb lattice Kitaev model,
and the Laughlin state of a fractional Chern insulator described by a
variational Monte Carlo wavefunction. The numerical results verifies the
analytic formula with high accuracy, and further suggests that this result
remains robust even when the edge states cannot be described by a conformal
field theory. Our result provides a new efficient approach to characterize and
identify topological states of matter from finite size numerics.Comment: 13 pages, 8 figure
Magnetic-flux-controlled giant Fano factor for the coherent tunneling through a parallel double-quantum-dot
We report our studies of zero-frequency shot noise in tunneling through a
parallel-coupled quantum dot interferometer by employing number-resolved
quantum rate equations. We show that the combination of quantum interference
effect between two pathways and strong Coulomb repulsion could result in a
giant Fano factor, which is controllable by tuning the enclosed magnetic flux.Comment: 11 pages, 2 figure
Evaluation of anti-hyperglycemic activities of phloridzin in diabetic mice
Background: The aim of the study was to investigate the hypoglycemic effects of Phloridzin.Methods and Materials: High fat diet induced diabetic KKAy mice were administered with phloridzin at an oral dose (60 mg/kg/day, ig.) for 10 weeks. A range of parameters, including blood glucose and lipid, serum insulin, glucose tolerance, were tested to evaluate its anti-hyperglycemic effects.Results: Phloridzin decreased water-intake, body weight, FBG, FINS, HOME-IR, Serum leptin, and CRP levels, increased serum adiponectin level in diabetic mice. Phloridzin also improved the oral glucose tolerance test (OGTT) to a certain degree. In addition, phloridzin decreased liver index, and epididymal, perirenal white adipose tissue indexs, increased pancreas index in diabetic mice. At last, phloridzin increased hepatic GK activity and hepatic glycogen level, decreased hepatic PEPCK, G-6-Pase activities in diabetic mice.Conclusions: Phloridzin possessed anti-hyperglycemic activities.Keywords: Diabetes, Phloridzin, FBG, Insulin resistance, Area under curv
Geometric bionics: Lotus effect helps polystyrene nanotube films get good blood compatibility
Various biomaterials have been widely used for manufacturing biomedical applications including artificial organs, medical devices and disposable clinical apparatus, such as vascular prostheses, blood pumps, artificial kidney, artificial hearts, dialyzers and plasma separators, which could be used in contact with blood^1^. However, the research tasks of improving hemocompatibility of biomaterials have been carrying out with the development of biomedical requirements^2^. Since the interactions that lead to surface-induced thrombosis occurring at the blood-biomaterial interface become a reason of familiar current complications with grafts therapy, improvement of the blood compatibility of artificial polymer surfaces is, therefore a major issue in biomaterials science^3^. After decades of focused research, various approaches of modifying biomaterial surfaces through chemical or biochemical methods to improve their hemocompatibility were obtained^1^. In this article, we report that polystyrene nanotube films with morphology similar to the papilla on lotus leaf can be used as blood-contacted biomaterials by virtue of Lotus effect^4^. Clearly, this idea, resulting from geometric bionics that mimicking the structure design of lotus leaf, is very novel technique for preparation of hemocompatible biomaterials
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