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1

Matching Names and Definitions of Topological Operators

\\u000a In previous empirical work humans did not recognize the definition of most topological operators for regions by their names\\u000a in two geospatial information systems (GIS). This work differentiates the not corresponding definitions and comprises more\\u000a topological terms in order to find better term\\/definition matches. The main hypothesis is that the majority of acceptable\\u000a matches – defined as matches selected by

Catharina Riedemann

2005-01-01

2

Topological Charge of Lattice Abelian Gauge Theory

Configuration space of abelian gauge theory on a periodic lattice becomes topologically disconnected by excising exceptional gauge field configurations. It is possible to define a U(1) bundle from the nonexceptional link variables by a smooth interpolation of the transition functions. The lattice analogue of Chern character obtained by a cohomological technique based on the noncommutative differential calculus is shown to give a topological charge related to the topological winding number of the U(1) bundle.

T. Fujiwara; H. Suzuki; K. Wu

2000-01-26

3

Background-independent charges in Topologically Massive Gravity

We construct background-independent Noether charges in Topologically Massive Gravity with negative cosmological constant using its first-order formulation. The procedure is carried out by keeping track of the surface terms in the variation of the action, regardless the value of the gravitational Chern-Simons coupling mu. In particular, this method provides a definition of conserved quantities for solutions at the chiral point

Olivera Miskovic; Rodrigo Olea

2009-01-01

4

Health Insurance Definitions Allowable Charge

Health Insurance Definitions Allowable Charge: Also referred to as the Allowed Amount, Approved considered payment-in-full by an insurance company and an associated network of healthcare providers. If the doctor is a member of your health insurance company's network of providers, he or she may be required

Buehrer, R. Michael

5

Thermodynamics of charged topological dilaton black holes

A class of $(n+1)$-dimensional topological black hole solutions in Einstein-Maxwell-dilaton theory with Liouville-type potentials for the dilaton field is presented. In these spacetimes, black hole horizon and cosmological horizon can be an $(n-1)$-dimensional positive, zero or negative constant curvature hypersurface. Because of the presence of the dilaton field, these topological black holes are neither asymptotically flat nor (anti)-de Sitter. We calculate the charge, mass, temperature, entropy and electric potential of these solutions. We also analyze thermodynamics of these topological black holes and disclose the effect of the dilaton field on the thermal stability of the solutions.

Ahmad Sheykhi

2007-10-15

6

Topology density correlator on dynamical domain-wall ensembles with nearly frozen topological charge

Global topological charge decorrelates very slowly or even freezes in fine lattice simulations. On the other hand, its local fluctuations are expected to survive and lead to the correct physical results as long as the volume is large enough. We investigate this issue on recently generated configurations including dynamical domain-wall fermions at lattice spacings a = 0.08 fm and finer. We utilize the Yang-Mills gradient flow to define the topological charge density operator and calculate its long-distance correlation, through which we propose a new method for extracting the topological susceptibility in a sub-volume. This method takes care of the finite volume correction, which reduces the bias caused by the global topological charge. Our lattice data clearly show a shorter auto-correlation time than that of the naive definition using the whole lattice, and are less sensitive to the global topological history. Numerical results show a clear sea-quark mass dependence, which agrees well with the prediction of chiral perturbation theory.

JLQCD collaboration; H. Fukaya; S. Aoki; G. Cossu; S. Hashimoto; T. Kaneko; J. Noaki

2014-11-13

7

Large statistics study of the topological charge distribution in the SU(3) gauge theory

We present preliminary results for a high statistics study of the topological charge distribution in the SU(3) Yang-Mills theory obtained by using the definition of the charge suggested by Neuberger fermions. We find statistical evidence for deviations from a gaussian distribution. The large statistics required has been obtained by using PCs of the INFN-GRID.

Leonardo Giusti; Silvano Petrarca; Bruno Taglienti

2007-05-22

8

Topology-based Feature Definition and Analysis

Defining high-level features, detecting them, tracking them and deriving quantities based on them is an integral aspect of modern data analysis and visualization. In combustion simulations, for example, burning regions, which are characterized by high fuel-consumption, are a possible feature of interest. Detecting these regions makes it possible to derive statistics about their size and track them over time. However, features of interest in scientific simulations are extremely varied, making it challenging to develop cross-domain feature definitions. Topology-based techniques offer an extremely flexible means for general feature definitions and have proven useful in a variety of scientific domains. This paper will provide a brief introduction into topological structures like the contour tree and Morse-Smale complex and show how to apply them to define features in different science domains such as combustion. The overall goal is to provide an overview of these powerful techniques and start a discussion how these techniques can aid in the analysis of astrophysical simulations.

Weber, Gunther H.; Bremer, Peer-Timo; Gyulassy, Attila; Pascucci, Valerio

2010-12-10

9

Topological charge in 1+1 dimensional lattice $?^4$ theory

We investigate the topological charge in 1+1 dimensional $\\phi^4$ theory on a lattice with Anti Periodic Boundary Condition (APBC) in the spatial direction. We propose a simple order parameter for the lattice theory with APBC and we demonstrate its effectiveness. Our study suggests that kink condensation is a possible mechanism for the order-disorder phase transition in the 1+1 dimensional $\\phi^4$ theory. With renormalizations performed on the lattice with Periodic Boundary Condition (PBC), the topological charge in the renormalized theory is given as the ratio of the order parameters in the lattices with APBC and PBC. We present a comparison of topological charges in the bare and the renormalized theory and demonstrate invariance of the charge of the renormalized theory in the broken symmetry phase.

Asit K. De; A. Harindranath; Jyotirmoy Maiti; Tilak Sinha

2005-11-10

10

Topological BPS charges in 10- and 11-dimensional supergravity

We consider the supersymmetry algebras of the maximal supergravities in 10 and 11 dimensions. We construct expressions from which the topological charge structure of the algebras can be determined in supersymmetric curved backgrounds. These are interpreted as the topological charges of the 1/2-BPS states that are found in the theories. We consider charges for all the M-, NS- and D-branes as well as the Kaluza-Klein monopoles. We also show that the dimensional reduction relations between the 11-dimensional and IIA charges, and T-duality relations of the IIA and IIB charges, match those found for the branes themselves. Finally we consider the massive versions of the IIA and 11-dimensional theories and find that the expressions for the charges, with a slight modification, are still valid in those instances.

Callister, Andrew K.; Smith, Douglas J. [Department of Mathematical Sciences, Durham University, Science Laboratories, South Road, Durham. DH1 3LE (United Kingdom)

2008-09-15

11

Diffusion of topological charge in lattice QCD simulations

NASA Astrophysics Data System (ADS)

We study the autocorrelations of observables constructed from the topological charge density, such as the topological charge on a time slice or in a subvolume, using a series of hybrid Monte Carlo simulations of pure SU(3) gauge theory with both periodic and open boundary conditions. We show that the autocorrelation functions of these observables obey a simple diffusion equation and we measure the diffusion coefficient, finding that it scales like the square of the lattice spacing. We use this result and measurements of the rate of tunneling between topological charge sectors to calculate the scaling behavior of the autocorrelation times of these observables on periodic and open lattices. There is a characteristic lattice spacing at which open boundary conditions become worthwhile for reducing autocorrelations and we show how this lattice spacing is related to the diffusion coefficient, the tunneling rate, and the lattice Euclidean time extent.

McGlynn, Greg; Mawhinney, Robert D.

2014-10-01

12

An Evaluation of 2-phase Charge Pump Topologies with Charge Transfer Switches for

to step up or step down the voltage. This approach has the advantages of a simple control method, reduced electronic devices. Charge pumps are inductorless DC-DC converters that are small size and high integration common charge pump topologies are evaluated in terms of voltage drop due to on-resistance and charge loss

Arslan, Tughrul

13

Weyl and Dirac semimetals with Z2 topological charge

NASA Astrophysics Data System (ADS)

We study the stability of gap-closing (Weyl or Dirac) points in the three-dimensional Brillouin zone of semimetals using Clifford algebras and their representation theory. We show that a pair of Weyl points with Z2 topological charge are stable in a semimetal with time-reversal and reflection symmetries when the square of the product of the two symmetry transformations equals minus identity. We present toy models of Z2 Weyl semimetals which have surface modes forming helical Fermi arcs. We also show that Dirac points with Z2 topological charge are stable in a semimetal with time-reversal, inversion, and SU(2) spin rotation symmetries when the square of the product of time-reversal and inversion equals plus identity. Furthermore, we briefly discuss the topological stability of point nodes in superconductors using Clifford algebras.

Morimoto, Takahiro; Furusaki, Akira

2014-06-01

14

Holographic QCD with Topologically Charged Domain-Wall/Membranes

We study the thermodynamical phase structures of holographic QCD with nontrivial topologically charged domain-wall/membranes which are originally related to the multiple $\\theta$-vacua in the large $N_c$ limit. We realize the topologically charged membranes as the holographic D6-brane fluxes in the Sakai-Sugimoto model. The D6-brane fluxes couple to the probe D8-anti-D8 via Chern-Simon term, and act as the source for the baryonic current density of QCD. We find rich phase structures of the dual meson system by varying asymptotic separation of D8 and anti-D8. Especially, there can be a thermodynamically favored and stable phase of finite baryonic current density. This provides the supporting evidence for the discovery of the topologically charged membranes found in the lattice QCD calculations. We also find a crossover phase with the limiting baryonic current density and temperature which suggest a Hagedorn-like phase transition of meson dissociation.

Feng-Li Lin; Shang-Yu Wu

2008-08-20

15

Simultaneous Magnetic and Charge Doping of Topological Insulators with Carbon

NASA Astrophysics Data System (ADS)

A two-step doping process, magnetic followed by charge or vice versa, is required to produce massive topological surface states (TSS) in topological insulators for many physics and device applications. Here, we demonstrate simultaneous magnetic and hole doping achieved with a single dopant, carbon, in Bi2Se3 by first-principles calculations. Carbon substitution for Se (CSe) results in an opening of a sizable surface Dirac gap (up to 82 meV), while the Fermi level remains inside the bulk gap and close to the Dirac point at moderate doping concentrations. The strong localization of 2p states of CSe favors spontaneous spin polarization via a p-p interaction and formation of ordered magnetic moments mediated by surface states. Meanwhile, holes are introduced into the system by CSe. This dual function of carbon doping suggests a simple way to realize insulating massive TSS.

Shen, Lei; Zeng, Minggang; Lu, Yunhao; Yang, Ming; Feng, Yuan Ping

2013-12-01

16

C library for topological study of the electronic charge density.

The topological study of the electronic charge density is useful to obtain information about the kinds of bonds (ionic or covalent) and the atom charges on a molecule or crystal. For this study, it is necessary to calculate, at every space point, the electronic density and its electronic density derivatives values up to second order. In this work, a grid-based method for these calculations is described. The library, implemented for three dimensions, is based on a multidimensional Lagrange interpolation in a regular grid; by differentiating the resulting polynomial, the gradient vector, the Hessian matrix and the Laplacian formulas were obtained for every space point. More complex functions such as the Newton-Raphson method (to find the critical points, where the gradient is null) and the Cash-Karp Runge-Kutta method (used to make the gradient paths) were programmed. As in some crystals, the unit cell has angles different from 90°, the described library includes linear transformations to correct the gradient and Hessian when the grid is distorted (inclined). Functions were also developed to handle grid containing files (grd from DMol® program, CUBE from Gaussian® program and CHGCAR from VASP® program). Each one of these files contains the data for a molecular or crystal electronic property (such as charge density, spin density, electrostatic potential, and others) in a three-dimensional (3D) grid. The library can be adapted to make the topological study in any regular 3D grid by modifying the code of these functions. PMID:22865338

Vega, David; Aray, Yosslen; Rodríguez, Jesús

2012-12-01

17

Glueballs and topological charge in the presence of dynamical quarks

We have estimated the string tension and the masses of the 0{sup ++} and 2{sup ++} glueballs in lattice QCD with 2 light flavours of staggered quarks. In addition we have measured the topological charge and hence susceptibility of our gauge field configurations. The simulations were performed at 6/g{sup 2}=5.6 and quark masses m=0.01 and 0.025 (lattice units) on lattice sizes ranging from 12{sup 4} to 16{sup 4}. 7 refs., 5 figs.

Bitar, K.M.; Edwards, R.; Heller, U.M.; Kennedy, A.D. (Florida State Univ., Tallahassee, FL (USA). Supercomputer Computations Research Inst.); DeGrand, T.A. (Colorado Univ., Boulder, CO (USA). Dept. of Physics); Gottlieb, S.; Kraznitz, A. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics); Kogut, J.B.; Renken, R.L. (Illinois Univ., Urbana, IL (USA). Dept. of Physics); Liu, W.; Rossi, P. (Thinking

1990-11-01

18

Mean Gradient Charge: A new definition of atomic charge using induced atomic gradient

NASA Astrophysics Data System (ADS)

A new definition of atomic charge, Mean Gradient Charge (MGC) is proposed on the basis of 'induced atomic gradient'. Conceptually the connection between electric response to external point charge and Coulomb's law made exact, providing a unique way of extracting atomic charges from quantum mechanical calculations without any numerical ambiguities. Furthermore MGC is relatively invariant with respect to molecular rotation, choices of basis set and even correlation treatments. Preliminary test calculations show that MGC values are in between Mulliken and NPA charges.

Choi, Cheol Ho

2012-02-01

19

NASA Astrophysics Data System (ADS)

In this letter we demonstrate that the fermionic zero modes on a superconducting domain wall can be associated to an one dimensional supersymmetry that contains non-trivial topological charges. In addition, the system also possesses three distinct supersymmetries with non-trivial topological charges and we also study some duality transformations of the supersymmetric algebras.

Oikonomou, V. K.

2015-01-01

20

(2+1)-dimensional charged black hole in topologically massive electrodynamics.

The 2+1 black hole coupled to a Maxwell field can be charged in two different ways. Besides a Coulomb field, whose potential grows logarithmically in the radial coordinate, there also exists a topological charge due to the existence of a noncontractible cycle. The topological charge does not gravitate and is somehow decoupled from the black hole. This situation changes if one turns on the Chern-Simons term for the Maxwell field. First, the flux integral at infinity becomes equal to the topological charge. Second, demanding regularity of the black hole horizon, the Coulomb charge must vanish identically. Hence, in 2+1 topologically massive electrodynamics coupled to gravity, the black hole can support holonomies only for the Maxwell field. This means that the charged black hole is constructed from the vacuum by means of spacetime identifications. PMID:16090671

Andrade, Tomás; Bañados, Máximo; Benguria, Rafael D; Gomberoff, Andrés

2005-07-01

21

Maximum-Likelihood Approach to Topological Charge Fluctuations in Lattice Gauge Theory

We present a novel technique for the determination of the topological susceptibility (related to the variance of the distribution of global topological charge) from lattice gauge theory simulations, based on maximum-likelihood analysis of the Markov-chain Monte Carlo time series. This technique is expected to be particularly useful in situations where relatively few tunneling events are observed. Restriction to a lattice subvolume on which topological charge is not quantized is explored, and may lead to further improvement when the global topology is poorly sampled. We test our proposed method on a set of lattice data, and compare it to traditional methods.

R. C. Brower; M. Cheng; G. T. Fleming; M. F. Lin; E. T. Neil; J. C. Osborn; C. Rebbi; E. Rinaldi; D. Schaich; C. Schroeder; G. Voronov; P. Vranas; E. Weinberg; O. Witzel

2014-07-24

22

Maximum-likelihood approach to topological charge fluctuations in lattice gauge theory

NASA Astrophysics Data System (ADS)

We present a novel technique for the determination of the topological susceptibility (related to the variance of the distribution of global topological charge) from lattice gauge theory simulations, based on maximum-likelihood analysis of the Markov-chain Monte Carlo time series. This technique is expected to be particularly useful in situations where relatively few tunneling events are observed. Restriction to a lattice subvolume on which topological charge is not quantized is explored, and may lead to further improvement when the global topology is poorly sampled. We test our proposed method on a set of lattice data, and compare it to traditional methods.

Brower, R. C.; Cheng, M.; Fleming, G. T.; Lin, M. F.; Neil, E. T.; Osborn, J. C.; Rebbi, C.; Rinaldi, E.; Schaich, D.; Schroeder, C.; Voronov, G.; Vranas, P.; Weinberg, E.; Witzel, O.

2014-07-01

23

NASA Astrophysics Data System (ADS)

We explore the charge transfer in the telomere G-Quadruplex (TG4) DNA theoretically by the nonequilibrium Green's function method, and reveal the topological effect of the charge transport in TG4 DNA. The consecutive TG4 (CTG4) is semiconducting with 0.2 0.3 eV energy gap. Charges transfer favorably in the CTG4, but are trapped in the nonconsecutive TG4 (NCTG4). The global conductance is inversely proportional to the local conductance for NCTG4. The topological structure transition from NCTG4 to CTG4 induces abruptly 3nA charge current, which provide a microscopic clue to understand the telomerase activated or inhibited by TG4. Our findings reveal the fundamental property of charge transfer in TG4 and its relationship with the topological structure of TG4.

Wang, Xin; Liang, Shi-Dong

2013-02-01

24

We explore charge transfer in the telomere G-Quadruplex (TG4) DNA theoretically by the nonequilibrium Green's function method, and reveal the topological effect of charge transport in TG4 DNA. The consecutive TG4(CTG4) is semiconducting with 0.2 ~ 0.3eV energy gap. Charges transfers favorably in the consecutive TG4, but are trapped in the non-consecutive TG4 (NCTG4). The global conductance is inversely proportional to the local conductance for NCTG4. The topological structure transition from NCTG4 to CTG4 induces abruptly ~ 3nA charge current, which provide a microscopic clue to understand the telomerase activated or inhibited by TG4. Our findings reveal the fundamental property of charge transfer in TG4 and its relationship with the topological structure of TG4.

Wang, Xin

2015-01-01

25

Momentum polarization: An entanglement measure of topological spin and chiral central charge

NASA Astrophysics Data System (ADS)

Topologically ordered states are quantum states of matter with topological ground-state degeneracy and quasiparticles carrying fractional quantum numbers and fractional statistics. The topological spin ?a=2?ha is an important property of a topological quasiparticle, which is the Berry phase obtained in the adiabatic self-rotation of the quasiparticle by 2?. For chiral topological states with robust chiral edge states, another fundamental topological property is the edge state chiral central charge c. In this paper we propose an approach to compute the topological spin and chiral central charge in lattice models by defining a quantity that we call 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 ha-(c)/(24) of topological spin and central charge. Results are obtained for two example systems, the non-Abelian phase of the honeycomb lattice Kitaev model and the ?=1/2 Laughlin state of a fractional Chern insulator described by a variational Monte Carlo wave function, which verify the analytic formula with high accuracy and further suggest that this result remains robust even when the edge states cannot be described by a conformal field theory. Our result provides an efficient approach to extract characteristic quantities of topological states of matter from finite size numerics.

Tu, Hong-Hao; Zhang, Yi; Qi, Xiao-Liang

2013-11-01

26

Observability of Same-Charge Lepton Topologies in Fully Leptonic Top Quark Pair Events in CMS

NASA Astrophysics Data System (ADS)

At the Large Hadron Collider dileptonic tbar t({+jets}) events can be selected with a relatively high signal-to-noise ratio and efficiency, with background events produced via Standard Model diagrams. Within the clean sample of these events, both isolated leptons have an opposite electric charge. In several models beyond the Standard Model tt/ bar t bar t(+{jets}) topologies are predicted, kinematically similar to the Standard Model tbar t({+jets}) signature, where both leptons have an equal electric charge. Such a signal of new physics can be diluted by the mis-identification of the leptons or their electric charge in Standard Model tbar t({+jets}) events. The observability of an excess of same-charge dilepton signals above the mis-reconstruction of the Standard Model background is presented, assuming the same topology. With an integrated luminosity of 30 fb-1, a same-charge dilepton signature of pp to tt/ bar t bar t events with a cross section larger than 1.2 pb is visible in the measurement of the ratio between same-charge and opposite-charge lepton pair events [J. D'Hondt, S. Lowette, G. Hammad, J. Heyninck, P. Van Mulders, ``Observability of same-charge lepton topology in dileptonic events t bar t'', CERN-CMS-NOTE-2006-065.

Lowette, S.

2007-02-01

27

Low-Lying Dirac Eigenmodes, Topological Charge Fluctuations and the Instanton Liquid Model

The local structure of low-lying eigenmodes of the overlap Dirac operator is studied. It is found that these modes cannot be described as linear combinations of 't Hooft "would-be" zeromodes associated with instanton excitations that underly the Instanton Liquid Model. This implies that the instanton liquid scenario for spontaneous chiral symmetry breaking in QCD is not accurate. More generally, our data suggests that the vacuum fluctuations of topological charge are not effectively dominated by localized lumps of unit charge with which the topological "would-be" zeromodes could be associated.

I. Horvath; S. J. Dong; T. Draper; F. X. Lee; H. B. Thacker; J. B. Zhang

2002-05-07

28

Charged Particle Environment Definition for NGST: Model Development

NASA Technical Reports Server (NTRS)

NGST will operate in a halo orbit about the L2 point, 1.5 million km from the Earth, where the spacecraft will periodically travel through the magnetotail region. There are a number of tools available to calculate the high energy, ionizing radiation particle environment from galactic cosmic rays and from solar disturbances. However, space environment tools are not generally available to provide assessments of charged particle environment and its variations in the solar wind, magnetosheath, and magnetotail at L2 distances. An engineering-level phenomenology code (LRAD) was therefore developed to facilitate the definition of charged particle environments in the vicinity of the L2 point in support of the NGST program. LRAD contains models tied to satellite measurement data of the solar wind and magnetotail regions. The model provides particle flux and fluence calculations necessary to predict spacecraft charging conditions and the degradation of materials used in the construction of NGST. This paper describes the LRAD environment models for the deep magnetotail (XGSE < -100 Re) and solar wind, and presents predictions of the charged particle environment for NGST.

Blackwell, William C.; Minow, Joseph I.; Evans, Steven W.; Hardage, Donna M.; Suggs, Robert M.

2000-01-01

29

FAST TRACK COMMUNICATION: Semiclassical central charge in topologically massive gravity

It is shown that the warped black hole geometries discussed recently in arXiv:0807.3040 (Anninos et al 2008) admit an algebra of asymptotic symmetries isomorphic to the semi-direct product of a Virasoro algebra and an algebra of currents. The realization of this asymptotic symmetry by canonical charges allows us to find the central charge of the Virasoro algebra. The right-moving central

Geoffrey Compère; Stéphane Detournay

2009-01-01

30

Topological charged black holes in generalized Ho?ava-Lifshitz gravity

NASA Astrophysics Data System (ADS)

As a candidate of quantum gravity in ultrahigh energy, the (3 +1 )-dimensional Ho?ava-Lifshitz (HL) gravity with critical exponent z ?1 indicates anisotropy between time and space at short distance. In the paper, we investigate the most general z =d Ho?ava-Lifshitz gravity in arbitrary spatial dimension d , with a generic dynamical Ricci flow parameter ? and a detailed balance violation parameter ? . In arbitrary dimensional generalized HLd +1 gravity with z ?d at long distance, we study the topological neutral black hole solutions with general ? in z =d HLd +1 , as well as the topological charged black holes with ? =1 in z =d HLd +1 . The HL gravity in the Lagrangian formulation is adopted, while in the Hamiltonian formulation, it reduces to Dirac-De Witt's canonical gravity with ? =1 . In particular, the topological charged black holes in z =5 HL6 , z =4 HL5 , z =3 ,4 HL4 , and z =2 HL3 with ? =1 are solved. Their asymptotical behaviors near the infinite boundary and near the horizon are explored, respectively. We also study the behavior of the topological black holes in the (d +1 )-dimensional HL gravity with U (1 ) gauge field in the zero temperature limit and finite temperature limit, respectively. Thermodynamics of the topological charged black holes with ? =1 , including temperature, entropy, heat capacity, and free energy are evaluated.

Li, Tian-Jun; Qi, Yong-Hui; Wu, Yue-Liang; Zhang, Yun-Long

2014-12-01

31

We calculate perturbative renormalization properties of the topological charge, using the standard lattice discretization given by a product of twisted plaquettes. We use the overlap and clover action for fermions, and the Symanzik improved gluon action for 4- and 6-link loops. We compute the multiplicative renormalization of the topological charge density to one loop; this involves only the gluon part of the action. The power divergent additive renormalization of the topological susceptibility is calculated to 3 loops.

A. Skouroupathis; H. Panagopoulos

2005-09-07

32

Experimental Charge Densities and Intermolecular Interactions: Electrostatic and Topological Analysis of DL-Histidine Philip Coppens,*, Yuriy Abramov, Michael Carducci,,1 Boris Korjov, Irina-resolution, low-temperature X-ray diffraction data set on DL-histidine, collected with a CCD detector, is used

Coppens, Philip

33

Measuring the fractional topological charge of LG beams by using interference intensity analysis

NASA Astrophysics Data System (ADS)

We demonstrate a method to measure the fractional topological charge (TC) of Laguerre-Gaussian (LG) beams by analyzing the interference intensity patterns between the vortex beam and its conjugate beam. By this method, the magnitude of integer and fractional TCs is quantitatively measured by using a simple unified formula. The proposed method can measure TCs up to 60.

Li, Xinzhong; Tai, Yuping; Lv, Fangjie; Nie, Zhaogang

2015-01-01

34

This paper introduces a simple novel method of transmission supplement charge allocation based on topological analysis of power flows in the network. The method uses the MW-MILE methodology but analyses the share, not the impact of, individual loads and generators in line flows. This results in positive contributions from all the users hence rescinding the problem of counterflows

J. Bialek

1997-01-01

35

Charge quantisation without magnetic monopoles: a topological approach to electromagnetism

The present work provides a theoretical explanation for the quantisation of electric charges, an open problem since Millikan's oil drop experiment in 1909. This explanation is based solely on Maxwell's theory, it recasts Electromagnetic theory under the language of complex line bundles; therefore, neither magnetic monopoles nor quantum mechanics are invoked. Essentially, the existence of magnetic monopoles was the only theoretical explanation for charge quantisation (e.g. Dirac's monopole), and there is no experimental data supporting their existence ---on the contrary, they have nerver been observed.

Romero Solha

2014-06-24

36

Low dimensional long range topological charge structure in the QCD vacuum

While sign-coherent 4-dimensional structures cannot dominate topological charge fluctuations in the QCD vacuum at all scales due to reflection positivity, it is possible that enhanced coherence exists over extended space-time regions of lower dimension. Using the overlap Dirac operator to calculate topological charge density, we present evidence for such structure in pure-glue SU(3) lattice gauge theory. It is found that a typical equilibrium configuration is dominated by two oppositely-charged sign-coherent connected structures (``sheets'') covering about 80% of space-time. Each sheet is built from elementary 3-d cubes connected through 2-d faces, and approximates a low-dimensional curved manifold (or possibly a fractal structure) embedded in the 4-d space. At the heart of the sheet is a ``skeleton'' formed by about 18% of the most intense space-time points organized into a global long-range structure, involving connected parts spreading over maximal possible distances. We find that the skeleton is locally 1-dimensional and propose that its geometrical properties might be relevant for understanding the possible role of topological charge fluctuations in the physics of chiral symmetry breaking.

I. Horvath; S.J. Dong; T. Draper; F.X. Lee; K.F. Liu; N. Mathur; H.B. Thacker; J.B. Zhang

2003-12-01

37

Comparison of converter topologies for charging capacitors used in pulsed load applications

NASA Technical Reports Server (NTRS)

The authors present a qualitative comparison of different power converter topologies which may be utilized for charging capacitors in pulsed power applications requiring voltages greater than 1 kV. The operation of the converters in capacitor charging applications is described, and relevant advantages are presented. All of the converters except one may be classified in the high-frequency switching category. One of the benefits from high-frequency operation is a reduction in size and weight. The other converter discussed is a member of the command resonant changing category. The authors first describe a boost circuit which functions as a command resonant charging circuit and utilizes a single pulse of current to charge the capacitor. The discussion of high-frequency converters begins with the flyback and Ward converters. Then, the series, parallel, and series/parallel resonant converters are examined.

Nelms, R. M.; Schatz, J. E.; Pollard, Barry

1991-01-01

38

Surface states of charge carriers in epitaxial films of the topological insulator Bi2Te3

NASA Astrophysics Data System (ADS)

The galvanomagnetic properties of p-type bismuth telluride heteroepitaxial films grown by the hot wall epitaxy method on oriented muscovite mica substrates have been investigated. Quantum oscillations of the magnetoresistance associated with surface electronic states in three-dimensional topological insulators have been studied in strong magnetic fields ranging from 6 to 14 T at low temperatures. The cyclotron effective mass, charge carrier mobility, and parameters of the Fermi surface have been determined based on the results of analyzing the magnetoresistance oscillations. The dependences of the cross-sectional area of the Fermi surface S( k F), the wave vector k F, and the surface concentration of charge carriers n s on the frequency of magnetoresistance oscillations in p-type Bi2Te3 heteroepitaxial films have been obtained. The experimentally observed shift of the Landau level index is consistent with the value of the Berry phase, which is characteristic of topological surface states of Dirac fermions in the films. The properties of topological surface states of charge carriers in p-type Bi2Te3 films obtained by analyzing the magnetoresistance oscillations significantly expand fields of practical application and stimulate the investigation of transport properties of chalcogenide films.

Luk'yanova, L. N.; Boikov, Yu. A.; Danilov, V. A.; Usov, O. A.; Volkov, M. P.; Kutasov, V. A.

2014-05-01

39

NASA Astrophysics Data System (ADS)

We propose that there might be emergent quasiparticles with fractional electronic charge such dyons on the domain wall between topological insulators and spin ice compounds through the Witten effect and interaction between the Dirac fermions and excited magnetic monopoles.

Sasaki, T.; Imai, E.; Kanazawa, I.

2014-12-01

40

A terahertz (THz) spiral phase plate with high transmission (>90% after Fresnel correction) and low dispersion has been developed based on the Tsurupica olefin polymer. Direct observations of the topological charge (both magnitude and sign) of a THz vortex beam are performed by using a THz camera with tilted lens focusing and radial defect introduction. The vortex outputs with a topological charge of ±1 (or ±2) are obtained at a frequency of 2 (or 4) THz.

Miyamoto, K., E-mail: k-miyamoto@faculty.chiba-u.jp [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Suizu, K.; Akiba, T. [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016 (Japan); Omatsu, T. [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); CREST Japan Science and Technology Agency, Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan)

2014-06-30

41

An Acoustic Charge Transport Imager for High Definition Television

NASA Technical Reports Server (NTRS)

This project, over its term, included funding to a variety of companies and organizations. In addition to Georgia Tech these included Florida Atlantic University with Dr. William E. Glenn as the P.I., Kodak with Mr. Mike Richardson as the P.I. and M.I.T./Polaroid with Dr. Richard Solomon as the P.I. The focus of the work conducted by these organizations was the development of camera hardware for High Definition Television (HDTV). The focus of the research at Georgia Tech was the development of new semiconductor technology to achieve a next generation solid state imager chip that would operate at a high frame rate (I 70 frames per second), operate at low light levels (via the use of avalanche photodiodes as the detector element) and contain 2 million pixels. The actual cost required to create this new semiconductor technology was probably at least 5 or 6 times the investment made under this program and hence we fell short of achieving this rather grand goal. We did, however, produce a number of spin-off technologies as a result of our efforts. These include, among others, improved avalanche photodiode structures, significant advancement of the state of understanding of ZnO/GaAs structures and significant contributions to the analysis of general GaAs semiconductor devices and the design of Surface Acoustic Wave resonator filters for wireless communication. More of these will be described in the report. The work conducted at the partner sites resulted in the development of 4 prototype HDTV cameras. The HDTV camera developed by Kodak uses the Kodak KAI-2091M high- definition monochrome image sensor. This progressively-scanned charge-coupled device (CCD) can operate at video frame rates and has 9 gm square pixels. The photosensitive area has a 16:9 aspect ratio and is consistent with the "Common Image Format" (CIF). It features an active image area of 1928 horizontal by 1084 vertical pixels and has a 55% fill factor. The camera is designed to operate in continuous mode with an output data rate of 5MHz, which gives a maximum frame rate of 4 frames per second. The MIT/Polaroid group developed two cameras under this program. The cameras have effectively four times the current video spatial resolution and at 60 frames per second are double the normal video frame rate.

Hunt, William D.; Brennan, Kevin; May, Gary; Glenn, William E.; Richardson, Mike; Solomon, Richard

1999-01-01

42

NASA Astrophysics Data System (ADS)

Majorana bound states have been a focus of condensed matter research for their potential applications in topological quantum computation. Here we utilize two charge-qubit arrays to explicitly simulate a DIII class one-dimensional superconductor model where Majorana end states can appear. Combined with one braiding operation, universal single-qubit operations on a Majorana-based qubit can be implemented by a controllable inductive coupling between two charge qubits at the ends of the arrays. We further show that in a similar way, a controlled-not gate for two topological qubits can be simulated in four charge-qubit arrays. Although the current scheme may not truly realize topological quantum operations, we elaborate that the operations in charge-qubit arrays are indeed robust against certain local perturbations.

Mao, Ting; Wang, Z. D.

2015-01-01

43

NSDL National Science Digital Library

A unit designed to develop logical reasoning through topology, using sorting, classifying, and patterning. Topology is about points, lines, and the figures they make; but length, area, curvature and angle can be altered as much as you wish. Thus topology is sometimes called Rubber-Sheet Geometry. Topics chosen are presented in a way that requires a minimum mathematical background and maturity; it is not assumed that students who use this unit know how to solve even simple equations or that they have much acquaintance with geometric figures.

Kaeley, Bhim S.

2007-04-03

44

Topology of the Spin-Polarized Charge Density in bcc and fcc Iron Travis E. Jones,1,* Mark E investigation of the topology of spin-polarized charge density, specifically in bcc and fcc iron. While, the spin-polarized charge densities of bcc and high-spin fcc iron are atypical. In these cases, the two

45

Topological charges in SL(2,R) covariant massive 11-dimensional and type IIB supergravity

NASA Astrophysics Data System (ADS)

In this paper we construct closed expressions that correspond to the topological charges of the various 1/2-BPS states of the maximal 10- and 11-dimensional supergravity theories. These expressions are related to the structure of the supersymmetry algebras in curved spacetimes. We mainly focus on IIB supergravity and 11-dimensional supergravity in a double M9-brane background, with an emphasis on the SL(2,R) multiplet structure of the charges and how these map between theories. This includes the charges corresponding to the multiplets of 7- and 9-branes in IIB. We find that examining the possible multiplet structures of the charges provides another tool for exploring the spectrum of BPS states that appear in these theories. As a prerequisite to constructing the charges we determine the field equations and multiplet structure of the 11-dimensional gauge potentials, extending previous results on the subject. The massive gauge transformations of the fields are also discussed. We also demonstrate how these massive gauge transformations are compatible with the construction of an SL(2,R) covariant kinetic term in the 11-dimensional Kaluza-Klein monopole worldvolume action.

Callister, Andrew K.; Smith, Douglas J.

2009-12-01

46

The Ehrenfest force field: Topology and consequences for the definition of an atom in a molecule

NASA Astrophysics Data System (ADS)

The Ehrenfest force is the force acting on the electrons in a molecule due to the presence of the other electrons and the nuclei. There is an associated force field in three-dimensional space that is obtained by the integration of the corresponding Hermitian quantum force operator over the spin coordinates of all of the electrons and the space coordinates of all of the electrons but one. This paper analyzes the topology induced by this vector field and its consequences for the definition of molecular structure and of an atom in a molecule. Its phase portrait reveals: that the nuclei are attractors of the Ehrenfest force, the existence of separatrices yielding a dense partitioning of three-dimensional space into disjoint regions, and field lines connecting the attractors through these separatrices. From the numerical point of view, when the Ehrenfest force field is obtained as minus the divergence of the kinetic stress tensor, the induced topology was found to be highly sensitive to choice of Gaussian basis sets at long range. Even the use of large split valence and highly uncontracted basis sets can yield spurious critical points that may alter the number of attraction basins. Nevertheless, at short distances from the nuclei, in general, the partitioning of three-dimensional space with the Ehrenfest force field coincides with that induced by the gradient field of the electron density. However, exceptions are found in molecules where the electron density yields results in conflict with chemical intuition. In these cases, the molecular graphs of the Ehrenfest force field reveal the expected atomic connectivities. This discrepancy between the definition of an atom in a molecule between the two vector fields casts some doubts on the physical meaning of the integration of Ehrenfest forces over the basins of the electron density.

Pendás, A. Martín; Hernández-Trujillo, J.

2012-10-01

47

Development of a subwavelength grating vortex coronagraph of topological charge 4 (SGVC4)

NASA Astrophysics Data System (ADS)

One possible solution to achieve high contrast direct imaging at a small inner working angle (IWA) is to use a vector vortex coronagraph (VVC), which provides a continuous helical phase ramp in the focal plane of the telescope with a phase singularity in its center. Such an optical vortex is characterized by its topological charge, i.e., the number of times the phase accumulates 2? radians along a closed path surrounding the singularity. Over the past few years, we have been developing a charge-2 VVC induced by rotationally symmetric subwavelength gratings (SGVC2), also known as the Annular Groove Phase Mask (AGPM). Since 2013, several SGVC2s (or AGPMs) were manufactured using synthetic diamond substrate, then validated on dedicated optical benches, and installed on 10-m class telescopes. Increasing the topological charge seems however mandatory for cancelling the light of bright stars which will be partially resolved by future Extremely Large Telescopes in the near-infrared. In this paper, we first detail our motivations for developing an SGVC4 (charge 4) dedicated to the near-infrared domain. The challenge lies in the design of the pattern which is unrealistic in the theoretically perfect case, due to state-of-the-art manufacturing limitations. Hence, we propose a new realistic design of SGVC4 with minimized discontinuities and optimized phase ramp, showing conclusive improvements over previous works in this field. A preliminary validation of our concept is given based on RCWA simulations, while full 3D finite-difference time-domain simulations (and eventually laboratory tests) will be required for a final validation.

Delacroix, Christian; Absil, Olivier; Carlomagno, Brunella; Piron, Pierre; Forsberg, Pontus; Karlsson, Mikael; Mawet, Dimitri; Habraken, Serge; Surdej, Jean

2014-08-01

48

An acoustic charge transport imager for high definition television applications

NASA Technical Reports Server (NTRS)

In this report we present the progress during the second six month period of the project. This includes both experimental and theoretical work on the acoustic charge transport (ACT) portion of the chip, the theoretical program modelling of both the avalanche photodiode (APD) and the charge transfer and overflow transistor and the materials growth and fabrication part of the program.

Hunt, William D.; Brennan, Kevin F.; Summers, Chris J.

1992-01-01

49

We discuss the thermal (or gravitational) responses in topological superconductors and in topological phases in general. Such thermal responses (as well as electromagnetic responses for conserved charge) provide a definition of topological insulators and superconductors beyond the single-particle picture. In two-dimensional topological phases, the Str\\v{e}da formula for the electric Hall conductivity is generalized to the thermal Hall conductivity. Applying this formula to the Majorana surface states of three-dimensional topological superconductors predicts cross-correlated responses between the angular momentum and thermal polarization (entropy polarization). We also discuss a use of D-branes in string theory as a systematic tool to derive all such topological terms and topological responses. In particular, we relate the $\\mathbb{Z}_2$ index of topological insulators introduced by Kane and Mele (and its generalization to other symmetry classes and to arbitrary dimensions) to the K-theory charge of non-BPS D-...

Furusaki, Akira; Nomura, Kentaro; Ryu, Shinsei; Takayanagi, Tadashi

2012-01-01

50

A unified phase transition picture of the charged topological black hole in Horava-Lifshitz gravity

Aiming at a unified phase transition picture of the charged topological black hole in Ho\\v{r}ava-Lifshitz gravity, we investigate this issue not only in canonical ensemble with the fixed charge case but also in grand-canonical ensemble with the fixed potential case. We firstly perform the standard analysis of the specific heat, the free energy and the Gibbs potential, and then study its geometrothermodynamics. It is shown that the local phase transition points not only witness the divergence of the specific heat, but also witness the minimum temperature and the maximum free energy or Gibbs potential. They also witness the divergence of the corresponding thermodynamic scalar curvature. No matter which ensemble is chosen, the metric constructed can successfully produce the behavior of the thermodynamic interaction and phase transition structure while other metrics failed to predict the phase transition point of the charged topological black hole in former literature. In grand-canonical ensemble, we have discovered the phase transition which has not been reported before. It is similar to the canonical ensemble in which the phase transition only takes place when $k=-1$. But it also has its unique characteristics that the location of the phase transition point depends on the value of potential, which is different from the canonical ensemble where the phase transition point is independent of the parameters. After an analytical check of Ehrenfest scheme, we find that the new phase transition is a second order one. It is also found that the thermodynamics of the black hole in Horava-Lifshitz gravity is quite different from that in Einstein gravity.

Jie-Xiong Mo; Xiao-Xiong Zeng; Gu-Qiang Li; Xin Jiang; Wen-Biao Liu

2014-04-09

51

The topological analysis of the charge density distribution in Cs(2)UO(2)Cl(4) obtained from an accurate X-ray diffraction experiment at 20K is reported. Details of the techniques applied during data collection and data refinement are discussed. A split Hansen-Coppens multipole model for uranium and cesium atoms has been used to describe the charge density features associated with valence electrons and core deformations. The analysis of the deformation density distribution, QTAIM space partitioning, the Laplacian of the electron density, and electron localization function are discussed. Local QTAIM descriptors for bonds to uranium and cesium are reported, as well as integrated properties of each individual atom. U(5f), U(6s), U(6p), U(6d), and U(7s) shells were required to describe the aspherical charge density of the uranium pseudoatom. Observed deformation of the cesium atom core was described by applying the multipole model to Cs(5s) and Cs(5p) shells. PMID:21919474

Zhurov, Vladimir V; Zhurova, Elizabeth A; Stash, Adam I; Pinkerton, A Alan

2011-11-17

52

Phase Fluctuations and the Absence of Topological Defects in Photo-excited Charge Ordered Nickelate

The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerging in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of measuring material properties at atomic and electronic time scales out of equilibrium, can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here we combine time-resolved femotosecond optical and resonant X-ray diffraction measurements on charge ordered La{sub 1.75}Sr{sub 0.25}NiO{sub 4} to reveal unforeseen photoinduced phase fluctuations of the charge order parameter. Such fluctuations preserve long-range order without creating topological defects, distinct from thermal phase fluctuations near the critical temperature in equilibrium. Importantly, relaxation of the phase fluctuations is found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limits charge order recovery. This new aspect of phase fluctuations provides a more holistic view of the phase's importance in ordering phenomena of quantum matter.

Lee, W.S.; Chuang, Y.D.; Moore, R.G.; Zhu, Y.; Patthey, L.; Trigo, M.; Lu, D.H.; Kirchmann, P.S.; Krupin, O.; Yi, M.; Langner, M.; Huse, N.; Robinson, J.S.; Chen, Y.; Zhou, S.Y.; Coslovich, G.; Huber, B.; Reis, D.A.; Kaindl, R.A.; Schoenlein, R.W.; Doering, D.

2012-05-15

53

An acoustic charge transport imager for high definition television applications

NASA Technical Reports Server (NTRS)

The primary goal of this research is to develop a solid-state television (HDTV) imager chip operating at a frame rate of about 170 frames/sec at 2 Megapixels/frame. This imager will offer an order of magnitude improvements in speed over CCD designs and will allow for monolithic imagers operating from the IR to UV. The technical approach of the project focuses on the development of the three basic components of the imager and their subsequent integration. The camera chip can be divided into three distinct functions: (1) image capture via an array of avalanche photodiodes (APD's); (2) charge collection, storage, and overflow control via a charge transfer transistor device (CTD); and (3) charge readout via an array of acoustic charge transport (ACT) channels. The use of APD's allows for front end gain at low noise and low operating voltages while the ACT readout enables concomitant high speed and high charge transfer efficiency. Currently work is progressing towards the optimization of each of these component devices. In addition to the development of each of the three distinct components, work towards their integration and manufacturability is also progressing. The component designs are considered not only to meet individual specifications but to provide overall system level performance suitable for HDTV operation upon integration. The ultimate manufacturability and reliability of the chip constrains the design as well. The progress made during this period is described in detail.

Hunt, W. D.; Brennan, K. F.; Summers, C. J.

1994-01-01

54

NASA Astrophysics Data System (ADS)

The Chern number is a genuine topological number. On the other hand, a symmetry protected topological (SPT) charge is a topological number only when a symmetry exists. We propose a formula for the SPT charge as a derivative of the Chern number in terms of the Green function in such a way that it is valid and related to the associated Hall current even when the symmetry is broken. We estimate the amount of deviation from the quantized value as a function of the strength of the broken symmetry. We present two examples. First, we consider Dirac electrons with the spin-orbit coupling on honeycomb lattice, where the SPT charges are given by the spin-Chern, valley-Chern and spin-valley-Chern numbers. Though the spin-Chern charge is not quantized in the presence of the Rashba coupling, the deviation is estimated to be 10-7 in the case of silicene, a silicon cousin of graphene. Second, we analyze the effect of the mirror-symmetry breaking of the mirror-Chern number in a thin-film of topological crystalline insulator.

Ezawa, Motohiko

2014-03-01

55

The Internet AS-Level Topology: Three Data Sources and One Definitive Metric

We calculate an extensive set of characteristics for Internet AS topologies extracted from the three data sources most frequently used by the research community: traceroutes, BGP, and WHOIS. We discover that traceroute and BGP topologies are similar to one another but dier substantially from the WHOIS topology. Among the widely considered metrics, we nd that the joint degree distribution appears

Priya Mahadevan; Dmitri V. Krioukov; Marina Fomenkov; Bradley Huffaker; Xenofontas A. Dimitropoulos; Kimberly C. Claffy; Amin Vahdat

2005-01-01

56

The internet AS-level topology: three data sources and one definitive metric

We calculate an extensive set of characteristics for Internet AS topologies extracted from the three data sources most frequently used by the research community: traceroutes, BGP, and WHOIS. We discover that traceroute and BGP topologies are similar to one another but differ substantially from the WHOIS topology. Among the widely considered metrics, we find that the joint degree distribution appears

Priya Mahadevan; Dmitri V. Krioukov; Marina Fomenkov; Xenofontas A. Dimitropoulos; Kimberly C. Claffy; Amin Vahdat

2006-01-01

57

An acoustic charge transport imager for high definition television applications

NASA Technical Reports Server (NTRS)

This report covers: (1) invention of a new, ultra-low noise, low operating voltage APD which is expected to offer far better performance than the existing volume doped APD device; (2) performance of a comprehensive series of experiments on the acoustic and piezoelectric properties of ZnO films sputtered on GaAs which can possibly lead to a decrease in the required rf drive power for ACT devices by 15dB; (3) development of an advanced, hydrodynamic, macroscopic simulator used for evaluating the performance of ACT and CTD devices and aiding in the development of the next generation of devices; (4) experimental development of CTD devices which utilize a p-doped top barrier demonstrating charge storage capacity and low leakage currents; (5) refinements in materials growth techniques and in situ controls to lower surface defect densities to record levels as well as increase material uniformity and quality.

Hunt, William D.; Brennan, Kevin F.; Summers, Christopher J.

1993-01-01

58

The doubly-connected polygonal geometry of planar graphene rings is found to bring forth topological configurations for accessing nontrivial relativistic quantum field (RQF) theory models that carry beyond the constant-mass Dirac-fermion theory. These include generation of sign-alternating masses, solitonic excitations, and charge fractionization. The work integrates a RQF Lagrangian formulation with numerical tight-binding Aharonov-Bohm electronic spectra and the generalized position-dependent-mass Dirac equation. In contrast to armchair graphene rings (aGRGs) with pure metallic arms, certain classes of aGRGs with semiconducting arms, as well as with mixed metallic-semiconducting ones, are shown to exhibit properties of one-dimensional nontrivial topological insulators. This further reveals an alternative direction for realizing a graphene-based nontrivial topological insulator through the manipulation of the honeycomb lattice geometry, without a spin-orbit contribution.

Constantine Yannouleas; Igor Romanovsky; Uzi Landman

2014-01-22

59

Topology of charge density and elastic properties of Ti3SiC2 polymorphs

Using an all-electron, full potential first-principles method, we have investigated the topology of charge density and elastic properties of the two polymorphs, alpha and beta, of Ti3SiC2. The bonding effect was analyzed based on Bader's quantum theory of ''atoms in molecules'' (AIM). It was found that the Ti-Si bonding effect is significantly weaker in beta than in alpha, giving less stabilizing effect for beta. The Si-C bonds, which are absent in alpha, are formed in beta and provide additional stabilizing effect for beta. In contrast to conventional thinking, there is no direction interaction between Ti atoms in both alpha and beta. The calculated elastic properties are in good agreement with the experimental results, giving the bulk modulus of about 180 GPa and the Poisson's ratio of 0.2. The beta phase is generally softer than the alpha phase. As revealed by the direction dependent Young's modulus, there is only slight elastic anisotropy in Ti3SiC2. For alpha, Young's modulus is minimum in the c direction and maximum in the directions 42o from c. For beta, the maximum lies in the c direction, in part due to the formation of Si-C bonds in this direction.

Yu, Rong; Zhang, Xiao Feng; He, Lian Long; Ye, Heng Qiang

2004-06-24

60

Phase transitions in charged topological black holes dressed with a scalar hair

Phase transitions in charged topological black holes dressed with a scalar field are studied. These black holes are solutions of the Einstein-Maxwell theory with a negative cosmological constant and a conformally coupled real self-interacting scalar field. Comparing, in the grand canonical ensemble, the free energies of the hairy and undressed black holes two different phase transitions are found. The first of them is one of second-order type and it occurs at a temperature defined by the value of the cosmological constant. Below this temperature an undressed black hole spontaneously acquires a scalar hair. The other phase transition is one of first-order type. The corresponding critical temperature, which is bounded from above by the one of the previous case, strongly depends on the coupling constant of the quartic self-interaction potential, and this transition only appears when the coupling constant is less than a certain value. In this case, below the critical temperature the undressed black is thermodynamically favored. However, when the temperature exceeds the critical value a hairy black hole is likely to be occur.

Cristian Martinez; Alejandra Montecinos

2010-09-28

61

Using ensembles generated with periodic or open boundary conditions in the temporal direction, and using Wilson flow or HYP smearing to smoothen the gauge fields, we have studied the Topological Charge Density Correlator (TCDC) and the Inverse Participation Ratio (IPR) for the topological charge density distribution in Lattice Yang-Mills theory. We have observed that at the same lattice volume and lattice spacing and at a given Wilson flow time, there is no noticeable difference between the TCDCs calculated with periodic and open boundary conditions in the temporal direction. The size of the positive core increases and the heights of the positive and negative peaks decrease with flow time, in both the cases. Open boundary condition makes it possible to compute observables at a smaller lattice spacing. On the other hand, the reference energy scale provided by Wilson flow allows us to study their scaling behaviour. At a particular Wilson flow time $t$ for all the lattice spacings investigated (except the larges...

Chowdhury, Abhishek; Maiti, Jyotirmoy

2014-01-01

62

The most basic characteristic of x-quasiperiodic solutions u(x,t) of the sine-Gordon equation u_{tt}-u_{xx}+\\sin u=0 is the topological charge density denoted $\\bar n$. The real finite-gap solutions u(x,t) are expressed in terms of the Riemann theta-functions of a non-singular hyperelliptic curve $\\Gamma$ and a positive generic divisor D of degree g on $\\Gamma$, where the spectral data $(\\Gamma, D)$ must satisfy some reality conditions. The problem addressed in note is: to calculate $\\bar n$ directly from the theta-functional expressions for the solution u(x,t). The problem is solved here by introducing what we call the multiscale or elliptic limit of real finite-gap sine-Gordon solutions. We deform the spectral curve to a singular curve, for which the calculation of topological charges reduces to two special easier cases.

P. G. Grinevich; K. V. Kaipa

2009-04-23

63

This paper presents a new single-stage power factor corrected (PFC) AC-DC converter. The topology is based on CIC-CPPFC (continuous input current charge-pump power factor correction) technique, achieving continuous conduction mode (CCM) input current with high power factor and reduced current ripple by using a coupled inductor, meeting IEC 61000-3-2 regulations for wide load range without additional input filter. The converter

Cícero S. Postiglione; Arnaldo J. Perin; Claudinor B. Nascimento

2008-01-01

64

Single-stage AC-DC converter with PFC based on continuous input current charge-pump topologies

This paper presents a single-stage power factor corrected (PFC) AC-DC converter. The topology is based on CIC-CPPFC (continuous input current charge-pump power factor correction) technique, achieving continuous conduction mode (CCM) input current with high power factor by using a coupled inductor, meeting IEC 61000-3-2 regulations for wide load range without additional input filter. Two different switching laws are tested. The

Cícero S. Postiglione; André L. Fuerback; Claudinor B. Nascimento; Arnaldo J. Perin

2009-01-01

65

NASA Astrophysics Data System (ADS)

We study topological phases in orthorhombic perovskite iridium (Ir) oxide superlattices grown along the [001 ] crystallographic axis. Bilayer Ir oxide superlattices display topological magnetic insulators exhibiting quantized anomalous Hall effects due to strong spin-orbit coupling of Ir 5 d orbitals and electronic correlation effects. We also find a valley Hall insulator with counterpropagating edge currents from two different valleys and a topological crystalline insulator with edge states protected by the crystal lattice symmetry based on stacking of two layers. In a single-layer superlattice, a topological insulator can be realized, when a strain field is applied to break the symmetry of a glide plane protecting the Dirac points. It turns into a topological magnetic insulator in the presence of magnetic ordering and/or in-plane magnetic field. We discuss essential ingredients for these topological phases and experimental signatures to test our theoretical proposals.

Chen, Yige; Kee, Hae-Young

2014-11-01

66

The perihelion precession, the deflection of light, and the radar echo delay are classical tests of General Relativity here used to probe brane world topologically charged black holes in a f(R) bulk and to constrain the parameter that arises from the Shiromizu-Maeda-Sasaki procedure applied to a f(R) bulk as well. The existing Solar system observational data constrain the possible values of the tidal charge parameter and the effective cosmological constant including f(R) brane world effects. We show that the observational/experimental data for both perihelion precession and radar echo delay make the black hole space of parameters to be more strict than the ones for the Dadhich, Maartens, Papadopoulos and Rezania (DMPR) black hole geometry. Furthermore, the deflection of light constrains the tidal charge parameter similarly as the DMPR black holes due to a peculiarity in the equation of motion.

Roldao da Rocha; A. M. Kuerten

2014-07-08

67

Charged Particle Environment Definition for NGST: L2 Plasma Environment Statistics

NASA Technical Reports Server (NTRS)

The plasma environment encountered by the Next Generation Space Telescope satellite in a halo orbit about L2 can include the Earth's magnetotail and magnetosheath in addition to the solar wind depending on the orbital radius chosen for the mission. Analysis of plasma environment impacts on the satellite requires knowledge of the average and extreme plasma characteristics to assess the magnitude of spacecraft charging and materials degradation expected for the mission lifetime. This report describes the analysis of plasma data from instruments onboard the IMP 8 and Geotail spacecraft used to produce the plasma database for the LRAD engineering-level phenomenology code developed to provide the NGST L2 environment definition.

Minow, Joseph I.; Blackwell, William C.; Neergaard, Linda F.; Evans, Steven W.; Hardage, Donna M.; Owens, Jerry K.

2000-01-01

68

NASA Astrophysics Data System (ADS)

Exchange interaction with surface magnetization exerts a local U(1) gauge field on Dirac fermions that exist on the surface of a topological insulator (TI). We show that the emergent gauge field gives rise to charge induction and polarization on the TI surface via the quantum anomalous Hall (QAH) effect. These phenomena correspond to an implementation of the Laughlin’s thought experiment [R. B. Laughlin, Phys. Rev. B 23, 5632 (1981)] without inserting a magnetic flux, and enable a local evaluation of the QAH transport on a specific TI surface.

Hattori, Kiminori

2014-03-01

69

The concept of (deterministic) dynamical chaos is well established and studied by now. Its field theoretic essence, however, has been revealed only very recently. Within the topological field theory (TFT) of dynamical systems (DS's), all (stochastic, continuous-time) DS's possess topological supersymmetry and chaos is the phenomenon of its spontaneous breakdown. Even though the TFT of DS is free of approximations and thus is technically solid, it is still missing a firm interpretational basis in order to be physically sound. Here, we make a few important steps toward the construction of the interpretational foundation for the TFT of DS. In particular, we discuss that one way to understand why the ground states of chaotic DS's are conditional probability densities, is that chaotic DS's fail to "thermalize" some of their variables and thus never reach thermodynamic equilibrium, \\emph{i.e.}, the defining assumption of the statistical physics approach that the ground state of the DS is a stationary total probability density.

Igor V. Ovchinnikov; Robert N. Schwartz; Kang L. Wang

2014-04-15

70

We discuss the thermal (or gravitational) responses in topological superconductors and in topological phases in general. Such thermal responses (as well as electromagnetic responses for conserved charge) provide a definition of topological insulators and superconductors beyond the single-particle picture. In two-dimensional topological phases, the Str\\v{e}da formula for the electric Hall conductivity is generalized to the thermal Hall conductivity. Applying this formula to the Majorana surface states of three-dimensional topological superconductors predicts cross-correlated responses between the angular momentum and thermal polarization (entropy polarization). We also discuss a use of D-branes in string theory as a systematic tool to derive all such topological terms and topological responses. In particular, we relate the $\\mathbb{Z}_2$ index of topological insulators introduced by Kane and Mele (and its generalization to other symmetry classes and to arbitrary dimensions) to the K-theory charge of non-BPS D-branes, and vice versa. We thus establish a link between the stability of non-BPS D-branes and the topological stability of topological insulators.

Akira Furusaki; Naoto Nagaosa; Kentaro Nomura; Shinsei Ryu; Tadashi Takayanagi

2012-11-02

71

NASA Astrophysics Data System (ADS)

A large class of symmetry-protected topological phases (SPT) in boson/spin systems have been recently predicted by the group cohomology theory. In this work, we consider bosonic SPT states at least with charge symmetry [U(1) or ZN] or spin-Sz rotation symmetry [U(1) or ZN] in two (2D) and three dimensions (3D) and the surface of 3D. If both are U(1), we apply external electromagnetic field/“spin gauge field” to study the charge/spin response. For the SPT examples we consider {i.e., Uc(1)?Z2T, Us(1)×Z2T, Uc(1)×[Us(1)?Z2]; subscripts c and s are short for charge and spin; Z2T and Z2 are time-reversal symmetry and ? rotation about Sy, respectively}, many variants of Witten effect in the 3D SPT bulk and various versions of anomalous surface quantum Hall effect are defined and systematically investigated. If charge or spin symmetry reduces to ZN by considering charge-N or spin-N condensate, instead of the linear response approach, we gauge the charge/spin symmetry, leading to a dynamical gauge theory with some remaining global symmetry. The 3D dynamical gauge theory describes a symmetry-enriched topological phase (SET), i.e., a topologically ordered state with global symmetry which admits nontrivial ground-state degeneracy depending on spatial manifold topology. For the SPT examples we consider, the corresponding SET states are described by dynamical topological gauge theory with topological BF term and axionic ? term in 3D bulk. In addition, the surface of SET is described by the chiral boson theory with quantum anomaly.

Ye, Peng; Wang, Juven

2013-12-01

72

In microwaves, a TE-polarized rectangular-waveguide resonator with an inserted thin ferrite disk gives an example of a nonintegrable system. The interplay of reflection and transmission at the disk interfaces together with the material gyrotropy effect gives rise to whirlpool-like electromagnetic vortices in the proximity of the ferromagnetic resonance. Based on numerical simulation, we show that a character of microwave vortices in a cavity can be analyzed by means of consideration of equivalent magnetic currents. Maxwell equations allows introduction of a magnetic current as a source of the electromagnetic field. Specifically, we found that in such nonintegrable structures, magnetic gyrotropy and geometrical factors leads to the effect of symmetry breaking resulting in effective chiral magnetic currents and topological magnetic charges. As an intriguing fact, one can observe precessing behavior of the electric-dipole polarization inside a ferrite disk.

Michael Sigalov; E. O. Kamenetskii; Reuven Shavit

2007-07-09

73

Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded \\qo{space} for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of OAM $\\ell$. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge $q$. When a circularly polarised light beam traverse...

Bouchard, Frédéric; Schulz, Sebastian A; Upham, Jeremy; Karimi, Ebrahim; Boyd, Robert W

2014-01-01

74

Using ensembles generated with periodic or open boundary conditions in the temporal direction, and using Wilson flow or HYP smearing to smoothen the gauge fields, we have studied the Topological Charge Density Correlator (TCDC) and the Inverse Participation Ratio (IPR) for the topological charge density distribution in Lattice Yang-Mills theory. We have observed that at the same lattice volume and lattice spacing and at a given Wilson flow time, there is no noticeable difference between the TCDCs calculated with periodic and open boundary conditions in the temporal direction. The size of the positive core increases and the heights of the positive and negative peaks decrease with flow time, in both the cases. Open boundary condition makes it possible to compute observables at a smaller lattice spacing. On the other hand, the reference energy scale provided by Wilson flow allows us to study their scaling behaviour. At a particular Wilson flow time $t$ for all the lattice spacings investigated (except the largest one), the TCDC data show universal behaviour within our statistical uncertainties. The behaviour of TCDC at a fixed Wilson flow time for different lattice spacings is contrasted with that of the data at a fixed HYP smearing level which show apparent scaling violation. The pseudoscalar glueball mass extracted from the TCDC appears to be insensitive to the lattice spacings (0.0345 fm $\\leq a \\leq$ 0.0667 fm) explored in this work. Expectation values of the IPR at different lattice spacings are found to be very close to each other at a given reference scale.

Abhishek Chowdhury; A. Harindranath; Jyotirmoy Maiti

2014-09-23

75

NASA Astrophysics Data System (ADS)

On the basis of coupled Ginzburg-Landau equations we study nonhomogeneous states in systems with two order parameters (OPs). Superconductors with a superconducting OP ? and a charge- or spin-density wave with amplitude W are examples of such systems. When one OP, say ? , has a form of a topological defect, like, e.g., a vortex or domain wall between the domains with the phases 0 and ? , the other OP W is determined by the Gross-Pitaevskii equation and is localized at the center of the defect. We consider in detail the domain-wall defect for ? and show that the shape of the associated solution for W depends on temperature and doping (or on the curvature of the Fermi surface) ? . It turns out that, provided the temperature or doping level is close to some discrete values Tn and ?n, the spatial dependence of the function W (x ) is determined by the form of the eigenfunctions of the linearized Gross-Pitaevskii equation. The spatial dependence of W0 corresponding to the ground state has the form of a soliton, while other possible solutions Wn(x ) have nodes. The inverse situation when W (x ) has the form of a topological defect and ? (x ) is localized at the center of this defect is also possible. In particular, we predict a surface or interfacial superconductivity in a system where a superconductor is in contact with a material that suppresses W . This superconductivity should have rather unusual temperature dependence existing only in certain intervals of temperature. Possible experimental realizations of such nonhomogeneous states of OPs are discussed.

Moor, Andreas; Volkov, Anatoly F.; Efetov, Konstantin B.

2014-12-01

76

Computational Topology Afra Zomorodian

Handbook, Second Edition, 2009. 1 #12;structures in Section 6. For topological data analysis, we describe of this section is topological spaces: their definitions, finite representations, and data structuresComputational Topology Afra Zomorodian Dartmouth College November 3, 2009 1 Introduction According

Zomorodian, Afra

77

Topological charged BPS vortices in Lorentz-violating Maxwell-Higgs electrodynamics

NASA Astrophysics Data System (ADS)

We have performed a complete study of BPS vortex solutions in the Abelian sector of the standard model extension (SME). Specifically, we have coupled the SME electromagnetism with a Higgs field which is supplemented with a Lorentz-violating CPT-even term. We have verified that Lorentz violation (LV) belonging to the Higgs sector allows us to interpolate between some well-known models like Maxwell-Higgs, Chern-Simons-Higgs, and Maxwell-Chern-Simons-Higgs. We can also observe that the electrical charged density distribution is non-null in both CPT-even and CPT-odd models; however, the total electric charge in the CPT-even case is null, whereas in the CPT-odd one it is proportional to the quantized magnetic flux. The following general results can be established in relation to the LV introduced in the Higgs sector: it changes the vortex ansatz and the gauge field boundary conditions. A direct consequence is that the magnetic flux, besides being proportional to the winding number, also depends explicitly on the Lorentz-violation belonging to the Higgs sector.

Casana, R.; Lazar, G.

2014-09-01

78

Topological charged BPS vortices in Lorentz-violating Maxwell-Higgs electrodynamics

We have performed a complete study of BPS vortex solutions in the Abelian sector of the standard model extension (SME). Specifically, we have coupled the SME electromagnetism with a Higgs field which is supplemented with a Lorentz-violating CPT-even term. We have verified that Lorentz violation (LV) belonging to the Higgs sector allows to interpolate between some well known models like, Maxwell-Higgs, Chern-Simons-Higgs and Maxwell-Chern-Simons-Higgs. We can also observed that the electrical charged density distribution is nonnull in both CPT-even and CPT-odd models; however, the total electric charge in the CPT-even case is null, whereas in the CPT-odd one it is proportional to the quantized magnetic flux. The following general results can be established in relation to the LV introduced in the Higgs sector: it changes the vortex ansatz and the gauge field boundary conditions. A direct consequence is that the magnetic flux, besides being proportional to the winding number, also depends explicitly on the Lorentz-violation belonging to the Higgs sector.

R. Casana; G. Lazar

2014-08-21

79

Spin torques and charge transport on the surface of topological insulator

NASA Astrophysics Data System (ADS)

We study various aspects of interplay between two-dimensional helical electrons, realized on the surface of a three-dimensional topological insulator, and the magnetization of a ferromagnet coupled to them. The magnetization is assumed to be perpendicular to the surface, with small transverse fluctuations u. In the first part of this paper, we calculate spin torques that the helical electrons exert on the magnetization. Up to first orders with respect to u, space/time derivative and electric current, we have determined all torques, which include Gilbert damping, spin renormalization, current-induced spin-orbit torques, and gradient corrections to them. Thanks to the identity between the velocity and spin in this model, these torques have exact interpretation in terms of transport phenomena, namely, diagonal conductivity, (anomalous) Hall conductivity, and corrections to them due to ordinary Hall effect on top of the anomalous one. These torque (and transport) coefficients are studied in detail with particular attention to the effects of vertex corrections and type of impurities (normal and magnetic). It is shown rigorously that the conventional current-induced torques, namely, spin-transfer torque and the so-called ? term, are absent. An electromotive force generated by spin dynamics, which is the inverse to the current-induced spin-orbit torque, is also studied. In the second part, we study the feedback effects arising as combinations of current-induced spin-orbit torques and spin-dynamics-induced electromotive force. It is demonstrated that the Gilbert damping process in this system is completely understood as a feedback effect. Another feedback effect, which may be called "magnon-drag electrical conductivity," is shown to violate the exact correspondence between spin-torque and transport phenomena demonstrated in the first part.

Sakai, Akio; Kohno, Hiroshi

2014-04-01

80

Smoke, fog, jelly, paints, milk and shaving cream are common everyday examples of colloids, a type of soft matter consisting of tiny particles dispersed in chemically distinct host media. Being abundant in nature, colloids also find increasingly important applications in science and technology, ranging from direct probing of kinetics in crystals and glasses to fabrication of third-generation quantum-dot solar cells. Because naturally occurring colloids have a shape that is typically determined by minimization of interfacial tension (for example, during phase separation) or faceted crystal growth, their surfaces tend to have minimum-area spherical or topologically equivalent shapes such as prisms and irregular grains (all continuously deformable--homeomorphic--to spheres). Although toroidal DNA condensates and vesicles with different numbers of handles can exist and soft matter defects can be shaped as rings and knots, the role of particle topology in colloidal systems remains unexplored. Here we fabricate and study colloidal particles with different numbers of handles and genus g ranging from 1 to 5. When introduced into a nematic liquid crystal--a fluid made of rod-like molecules that spontaneously align along the so-called 'director'--these particles induce three-dimensional director fields and topological defects dictated by colloidal topology. Whereas electric fields, photothermal melting and laser tweezing cause transformations between configurations of particle-induced structures, three-dimensional nonlinear optical imaging reveals that topological charge is conserved and that the total charge of particle-induced defects always obeys predictions of the Gauss-Bonnet and Poincaré-Hopf index theorems. This allows us to establish and experimentally test the procedure for assignment and summation of topological charges in three-dimensional director fields. Our findings lay the groundwork for new applications of colloids and liquid crystals that range from topological memory devices, through new types of self-assembly, to the experimental study of low-dimensional topology. PMID:23263182

Senyuk, Bohdan; Liu, Qingkun; He, Sailing; Kamien, Randall D; Kusner, Robert B; Lubensky, Tom C; Smalyukh, Ivan I

2013-01-10

81

NASA Astrophysics Data System (ADS)

In the presence of axial magnetic fields that can be realized in deliberately buckled monolayer graphene, quasirelativistic Dirac fermions may find themselves in a variety of broken-symmetry phases even for weak repulsive interactions. Through a detailed Hartree self-consistent numerical calculation in finite strained graphene with cylindrical and open boundaries, we establish the possibility of realizing a charge-density wave order for the spinless fermions in the presence of weak nearest-neighbor repulsion. Such an instability gives rise to a staggered pattern of average fermionic density between bulk and boundary of the system as well as among two sublattices of honeycomb lattice, due to the spatial separation of the zero-energy states localized on opposite sublattices. Although with fermions spin restored, an unconventional magnetic order driven by the onsite repulsion possibly leads to the dominant instability at the Dirac point, the proposed charge-density wave order can nevertheless be realized at finite doping, which is always accompanied by a finite ferromagnetic moment. Additionally, the charge-density wave phase supports a quantized charge or spin Hall conductivity when its formation away from the Dirac point is further preceded by the appearance of topological anomalous or spin Hall insulator, respectively. The topological orders in strained graphene can be supported by weak second-neighbor repulsion, for example. Therefore, depending on the relative strength of various short-range components of the Coulomb interaction, several broken-symmetry phases can be realized within the zero-energy manifold in strained graphene.

Roy, Bitan; Sau, Jay D.

2014-08-01

82

NSDL National Science Digital Library

Geometry and Topology is "a fully refereed international journal dealing with all aspects of geometry and topology and their applications." The publisher, Geometry & Topology Publications (GTP), is a non-profit organization based in the Mathematics Department of the University of Warwick at Coventry, UK. Visitors can browse the journal, available free of charge electronically, or search by keyword or author. The moderate collection within the Geometry and Topology Monographs series includes research monographs and refereed conference proceedings.

83

We show that in the presence of free charge carriers the definition of the frequency-dependent dielectric permittivity requires additional regularization. As an example, the dielectric permittivity of the Drude model is considered and its time-dependent counterpart is derived and analyzed. The respective electric displacement cannot be represented in terms of the standard Fourier integral. The regularization procedure allowing to circumvent these difficulties is suggested. For purpose of comparison it is shown that the frequency-dependent dielectric permittivity of insulators satisfies all rigorous mathematical criteria. This permits us to conclude that in the presence of free charge carriers the concept of dielectric permittivity is not as well defined as for insulators and we make a link to widely discussed puzzles in the theory of thermal Casimir force which might be caused by the use of such kind permittivities.

M. Bordag; B. Geyer; G. L. Klimchitskaya; V. M. Mostepanenko

2009-11-17

84

Topological Solitons in Physics.

ERIC Educational Resources Information Center

A broad definition of solitons and a discussion of their role in physics is given. Vortices and magnetic monopoles which are examples of topological solitons in two and three spatial dimensions are described in some detail. (BB)

Parsa, Zohreh

1979-01-01

85

Within the framework of the molecular orbital (MO) theory, the addition of one electron to the 4sigma antibonding orbital of the neutral (F...H) system or the removal of one electron from its pi nonbonding orbitals, leading to (F...H)- and to (F...H)+, has permitted the investigation of these charge perturbations on the bond properties of the hydrogen fluoride molecule by using the topological analysis of rho(r). For (F...H), (F...H)-, and (F...H)+, the topological and energetic properties calculated at the F...H bond critical point (BCP) have been related to the 3sigma bonding molecular orbital (BMO) distribution, as this orbital is the main contributor to rho(r) at the interatomic surface. The analysis has been carried out at several F...H internuclear distances, ranging from 0.8 to 3.0 A. As far as the BMO distribution results from its interaction with the average Coulomb and exchange potential generated by the charge filling the other MOs, and in particular by the pi and 4sigma electrons, the comparison between the BCP properties calculated for the charged systems and those corresponding to the neutral one permits the interpretation of the differences in terms of the charge perturbation on BMO. Along with the BCP properties of (F...H), (F...H)-, and (F...H)+, the interaction energy magnitudes of these systems have been also calculated within the same range of internuclear distances, indicating that the applied perturbations do not break the F-H bond but soften it, giving rise to the stable species (F-H)- and (F-H)+. Comparing the three systems at their equilibrium geometries, the most stable configuration, which corresponds to the unperturbed (F...H) system, shows the highest quantity and the most locally concentrated charge density distribution, along with the largest total electron energy density magnitude, at the interatomic surface as a consequence of the BMO contraction toward the fluorine nucleus in (F...H)+ and of the BMO expansion toward both nuclei in (F...H)-. On the other hand, if the comparison is carried out at the equilibrium distance of (F...H) (d(eq)0), this one exhibits both the smallest total energy density magnitude and the largest quantity of bonding charge at the interatomic surface. Hence, being the signature of the most stable configuration, the characteristic magnitudes of the neutral system rho(d(eq)0), inverted triangle2 rho(d(eq)0), and H(d(eq)0) appear as boundary conditions at the interatomic surface of its unperturbed and relaxed electron distribution. PMID:16833999

Espinosa, Enrique; Alkorta, Ibon; Mata, Ignasi; Molins, Elies

2005-07-28

86

NASA Astrophysics Data System (ADS)

I. Topology as universal concept. Optical vorticulture / M. V. Berry. On universality of mathematical structure in nature: topology / T. Matsuyama. Topology in physics / R. Jackiw. Isoholonomic problem and holonomic quantum computation / S. Tanimura -- II. Topological crystals. Topological crystals of NbSe[symbol] / S. Tanda ... [et al.]. Superconducting states on a Möbius strip / M. Hayashi ... [et al.]. Structure analyses of topological crystals using synchrotron radiation / Y. Nogami ... [et al.]. Transport measurement for topological charge density waves / T. Matsuura ... [et al.]. Theoretical study on Little-Parks oscillation in nanoscale superconducting ring / T. Suzuki, M. Hayashi and H. Ebisawa. Frustrated CDW states in topological crystals / K. Kuboki ... [et al.]. Law of growth in topological crystal / M. Tsubota ... [et al.]. Synthesis and electric properties of NbS[symbol]: possibility of room temperature charge density wave devices / H. Nobukane ... [et al.]. How does a single crystal become a Möbius strip? / T. Matsuura ... [et al.]. Development of X-ray analysis method for topological crystals / K. Yamamoto ... [et al.] -- III. Topological materials. Femtosecond-timescale structure dynamics in complex materials: the case of (NbSe[symbol])[symbol]I / D. Dvorsek and D. Mihailovic. Ultrafast dynamics of charge-density-wave in topological crystals / K. Shimatake ... [et al.]. Topology in morphologies of a folded single-chain polymer / Y. Takenaka, D. Baigl and K. Yoshikawa. One to two-dimensional conversion in topological crystals / T. Toshima, K. Inagaki and S. Tanda. Topological change of Fermi surface in Bismuth under high pressure / M. Kasami ... [et al.]. Topological change of 4, 4'-bis[9-dicarbazolyl]-2, 2'-biphenyl (CBP) by international rearrangement / K. S. Son ... [et al.]. Spin dynamics in Heisenberg triangular system VI5 cluster studied by [symbol]H-NMR / Y. Furukawa ... [et al.]. STM/STS on NbSe[symbol] nanotubes / K. Ichimura ...[et al.]. Nanofibers of hydrogen storage alloy / I. Saita ... [et al.]. Synthesis of stable icosahedral quasicrystals in Zn-Sc based alloys and their magnetic properties / S. Kashimoto and T. Ishimasa. One-armed spiral wave excited by eam pressure in accretion disks in Be/X-Ray binaries / K. Hayasaki and A. T. Okazaki -- IV. Topological defects and excitations. Topological excitations in the ground state of charge density wave systems / P. Monceau. Soliton transport in nanoscale charge-density-wave systems / K. Inagaki, T. Toshima and S. Tanda. Topological defects in triplet superconductors UPt3, Sr[symbol]RuO[symbol], etc. / K. Maki ... [et al.]. Microscopic structure of vortices in type II superconductors / K. Machida ... [et al.]. Microscopic neutron investigation of the Abrikosov state of high-temperature superconductors / J. Mesot. Energy dissipation at nano-scale topological defects of high-Tc superconductors: microwave study / A. Maeda. Pressure induced topological phase transition in the heavy Fermion compound CeAl[symbol] / H. Miyagawa ... [et al.]. Explanation for the unusual orientation of LSCO square vortex lattice in terms of nodal superconductivity / M. Oda. Local electronic states in Bi[symbol]Sr[symbol]CaCu[symbol]O[symbol] / A. Hashimoto ... [et al.] -- V. Topology in quantum phenomena. Topological vortex formation in a Bose-Einstein condensate of alkali-metal atoms / M. Nakahara. Quantum phase transition of [symbol]He confined in nano-porous media / K. Shirahama, K. Yamamoto and Y. Shibayama. A new mean-field theory for Bose-Einstein condensates / T. Kita. Spin current in topological cristals / Y. Asano. Antiferromagnetic defects in non-magnetic hidden order of the heavy-electron system URu[symbol]Si[symbol] / H. Amitsuka, K. Tenya and M. Yokoyama. Magnetic-field dependences of thermodynamic quantities in the vortex state of Type-II superconductors / K. Watanabe, T. Kita and M. Arai. Three-magnon-mediated nuclear spin relaxation in quantum ferrimagnets of topological origin / H. Hori and S, Yamamoto. Topological aspects of wave function statistics at t

Tanda, Satoshi; Matsuyama, Toyoki; Oda, Migaku; Asano, Yasuhiro; Yakubo, Kousuke

2006-08-01

87

NASA Astrophysics Data System (ADS)

We detected the spin polarization due to charge flow in the spin non-degenerate surface state of a three dimensional topological insulator by means of an all-electrical method. The charge current in the bulk-insulating topological insulator Bi1.5Sb0.5Te1.7Se1.3 (BSTS) was injected/extracted through a ferromagnetic electrode made of Ni80Fe20, and an unusual current-direction-dependent magnetoresistance gives evidence for the appearance of spin polarization which leads to a spin-dependent resistance at the BSTS/Ni80Fe20 interface. In contrast, our control experiment on Bi2Se3 gave null result. These observations demonstrate the importance of the Fermi-level control for the electrical detection of the spin polarization in topological insulators.

Ando, Yuichiro; Hamasaki, Takahiro; Kurokawa, Takayuki; Ichiba, Kouki; Yang, Fan; Novak, Mario; Sasaki, Satoshi; Segawa, Kouji; Ando, Yoichi; Shiraishi, Masashi

2014-11-01

88

We detected the spin polarization due to charge flow in the spin nondegenerate surface state of a three-dimensional topological insulator by means of an all-electrical method. The charge current in the bulk-insulating topological insulator Bi1.5Sb0.5Te1.7Se1.3 (BSTS) was injected/extracted through a ferromagnetic electrode made of Ni80Fe20, and an unusual current-direction-dependent magnetoresistance gave evidence for the appearance of spin polarization, which leads to a spin-dependent resistance at the BSTS/Ni80Fe20 interface. In contrast, our control experiment on Bi2Se3 gave null result. These observations demonstrate the importance of the Fermi-level control for the electrical detection of the spin polarization in topological insulators. PMID:25330016

Ando, Yuichiro; Hamasaki, Takahiro; Kurokawa, Takayuki; Ichiba, Kouki; Yang, Fan; Novak, Mario; Sasaki, Satoshi; Segawa, Kouji; Ando, Yoichi; Shiraishi, Masashi

2014-11-12

89

Topological pumping over a photonic Fibonacci quasicrystal

Quasiperiodic lattices have recently been shown to be a nontrivial topological phase of matter. Charge pumping—one of the hallmarks of topological states of matter—was recently realized for photons in a one-dimensional ...

Verbin, Mor

90

ERIC Educational Resources Information Center

We continue our study of topological X-rays begun in Lynch ["Topological X-rays and MRI's," iJMEST 33(3) (2002), pp. 389-392]. We modify our definition of a topological magnetic resonance imaging and give an affirmative answer to the question posed there: Can we identify a closed set in a box by defining X-rays to probe the interior and without…

Lynch, Mark

2012-01-01

91

AdS Boundary Conditions and the Topologically Massive Gravity/CFT Correspondence

The AdS/CFT correspondence provides a new perspective on recurrent questions in General Relativity such as the allowed boundary conditions at infinity and the definition of gravitational conserved charges. Here we review the main insights obtained in this direction over the last decade and apply the new techniques to Topologically Massive Gravity. We show that this theory is dual to a non-unitary CFT for any value of its parameter mu and becomes a Logarithmic CFT at mu = 1.

Skenderis, Kostas; Taylor, Marika; Rees, Balt C. van [Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)

2009-12-15

92

Topology Optimization of Tensegrity Structures Based on Nonsmooth Mechanics

Topology Optimization of Tensegrity Structures Based on Nonsmooth Mechanics Yoshihiro Kanno University of Tokyo (Japan) November 14, 2011 #12;tensegrity -- definition Topology Optimization of Tensegrity Structures ACOMEN 2011 Â· tension + integrity [Fuller 75] [Emmerich], [Snelson] Â· pin

Kanno, Yoshihiro

93

Topological Index Theorem on the Lattice through the Spectral Flow of Staggered Fermions

We investigate numerically the spectral flow introduced by Adams for the staggered Dirac operator on realistic (quenched) gauge configurations. We obtain clear numerical evidence that the definition works as expected: there is a clear separation between crossings near and far away from the origin, and the topological charge defined through the crossings near the origin agrees, for most configurations, with the one defined through the near-zero modes of large taste-singlet chirality of the staggered Dirac operator. The crossings are much closer to the origin if we improve the Dirac operator used in the definition, and they move towards the origin as we decrease the lattice spacing.

V. Azcoiti; G. Di Carlo; E. Follana; A. Vaquero

2014-10-21

94

Call a topology well if and only if every open is com- pact. The starting point of this note is that this notion generalizes that of well-quasi order, in the sense that an Alexandroff topology is well if and only if its specialisation quasi-ordering is well. For more general topologies, this opens the way to verifying infinite transition systems based

Jean Goubault-Larrecq

95

Variational problems with topological constraints

. We introduce a decomposition that captures much of the topology of level sets for functions in certain Sobolev spaces, and\\u000a allows the definition of an analog of the decreasing rearrangement of a function which respects the topology of level sets.\\u000a In a variety of settings this decomposition is preserved under weak limits, and so is useful in establishing existence

Peter Laurence; Edward W. Stredulinsky

2000-01-01

96

Theory of topological insulators

NASA Astrophysics Data System (ADS)

An important goal of condensed matter physics is to search for new phases of matter. This thesis is about a new insulating phase. Traditionally an insulator is defined as a material that does not conduct electricity. In most insulators the absence of electrical conduction is explained by the band theory of solids---a triumph of quantum mechanics in the twentieth century. According to band theory, an insulator has an energy gap separating the conduction and valence bands. As a result, there is no low energy electronic states inside an insulator to accommodate a charge flow. In the past few years, a new kind of insulators has been theoretically predicted, which has a band structure that is topologically different from an ordinary insulator. For this reason, this new state is called a topological insulator. Despite having an energy gap in the bulk, a topological insulator has unique gapless states bound to the sample surface as a consequence of the topological order in the bulk. Recent experimental observations of these unique surface electron states have provided direct evidence of the topological insulator phase in a number of materials. In this thesis we present the theory of topological insulators. Specifically, we describe the mathematical formulation of the topological order of insulating band structures, which leads to the theoretical discovery of three-dimensional topological insulator phases. We also give the physical characterization of the topological order, thereby establishing that the hallmark signatures of topological insulators are the distinctive surface states. Unlike any other two dimensional metal, the surface of a topological insulator has unique properties giving rise to unusual phases. In particular, we show that depositing a superconductor on the surface leads, via proximity effect, to a novel superconducting state which hosts zero energy Majorana fermions. A Majorana fermion is theoretically defined as a particle that is its own anti-particle but has never been found in nature. Zero-energy Majorana fermions are predicted to have non-Abelian statistics which, if observed, will greatly advance our understanding of the fundamental principles of quantum statistics and open the door to potential quantum computation applications. We propose that the superconductor-topological insulator interface provides a new venue for observing Majorana fermions and their non-Abelian statistics.

Fu, Liang

97

NASA Astrophysics Data System (ADS)

Current and future technological needs increasingly motivate the intensive scientific research of the properties of materials at the nano-scale. One of the most important domains in this respect at present concerns nano-electronics and its diverse applications. The great interest in this domain arises from the potential reduction of the size of the circuit components, maintaining their quality and functionality, and aiming at greater efficiency, economy, and storage characteristics for the corresponding physical devices. The aim of this thesis is to present a contribution to the analysis of the electronic charge and spin transport phenomena that occur at the quantum level in nano-structures. This thesis spans the areas of quantum transport theory through time-dependent systems, electron-boson interacting systems and systems of interest to spintronics. A common thread in the thesis is to develop the theoretical foundations and computational algorithms to numerically simulate such systems. In order to optimize the numerical calculations I resort to different techniques (such as graph theory in finding inverse of a sparse matrix, adaptive grids for integrations and programming languages (e.g., MATLAB and C++) and distributed computing tools (MPI, CUDA). Outline of the Thesis: After giving an introduction to the topics covered in this thesis in Chapter 1, I present the theoretical foundations to the field of non-equilibrium quantum statistics in Chapter 2. The applications of this formalism and the results are covered in the subsequent chapters as follows: Spin and charge quantum pumping in time-dependent systems: Covered in Chapters 3, 4 and 5, this topics was initially motivated by experiments on measuring voltage signal from a magnetic tunnel junction (MTJ) exposed to a microwave radiation in ferromagnetic resonance (FMR) condition. In Chapter 3 we found a possible explanation for the finite voltage signal measured from a tunnel junction consisting of only a single ferromagnet (FM). I show that this could be due to the existence of Rashba spin-orbit coupling (SOC) at the interface of the FM and insulator. Assuming that the measured signals are quantum mechanical effect where a solution to the time dependent Schrodinger equation is required, I use Keldysh Green function formalism to introduce a "multi-photon" approach which takes into account the effects of time-dependent term exactly up to scatterings from a finite number of photons. We then proceed to find the corresponding Green function numerically using a recursive method which allows us to increase the size of the system significantly. We also implement other approximations such as adiabatic and rotating frame approaches and compared them with our approach. In Chapter 4, I investigate the spin and charge pumping from a precessing magnetization attached to the edge of a 2-dimensional topological insulator (2DTI). We show that, in this system a huge spin current (or voltage signal if the FM covers only one edge) can be pumped for very small cone angles of the precessing FM (proportional to the intensity of the applied microwave). In Chapter 5 I present the third project in this field of research, where, I investigated the pumping from FM attached to a 3-dimensional TI. Spin-transfer torque: Presented in Chapter 6, in this work I investigate the torque induced by a flow of spin-polarized current into a FM and check the condition in which it can cause the magnetization to flip. Motivated by recent experimental developments in the field, here I consider systems with strong SOC such as TIs within a magnetic tunnel junction (MTJ) heterostructure. In the theoretical part I show the correct way (as opposed to the conventional approach used in some theoretical works which suffers from violation of the gauge invariance) to calculate linear-response torque to the external applied voltage and for the numerical calculation I adopted a parallelized adaptive integration algorithm in order to take care of very sharp changes that appear in momentum and energy dependence of t

Mahfouzi, Farzad

98

Topology Explains Why Automobile Sunshades Fold Oddly

ERIC Educational Resources Information Center

Automobile sunshades always fold into an "odd" number of loops. The explanation why involves elementary topology (braid theory and linking number, both explained in detail here with definitions and examples), and an elementary fact from algebra about symmetric group.

Feist, Curtis; Naimi, Ramin

2009-01-01

99

Atomic-size vortex beams have great potential in probing materials' magnetic moment at atomic scales. However, the limited depth of field of vortex beams constrains the probing depth in which the helical phase front is preserved. On the other hand, electron channeling in crystals can counteract beam divergence and extend the vortex beam without disrupting its topological charge. Specifically, in this paper, we report atomic vortex beams with topological charge \\pm1 can be coupled to the 2p columnar bound states and propagate for more 50 nm without being dispersed and losing its helical phase front. We gave numerical solutions to the 2p columnar orbitals and tabulated the characteristic size of the 2p states of two typical elements, Co and Dy, for various incident beam energies and various atomic densities. The tabulated numbers allow estimates of the optimal convergence angle for maximal coupling to 2p columnar orbital. We also have developed analytic formulae for beam energy, convergence-angle, and hologram ...

Xin, Huolin L

2012-01-01

100

NASA Astrophysics Data System (ADS)

The application of topology, the mathematics of conserved properties under continuous deformations, is creating a range of new opportunities throughout photonics. This field was inspired by the discovery of topological insulators, in which interfacial electrons transport without dissipation, even in the presence of impurities. Similarly, the use of carefully designed wavevector-space topologies allows the creation of interfaces that support new states of light with useful and interesting properties. In particular, this suggests unidirectional waveguides that allow light to flow around large imperfections without back-reflection. This Review explains the underlying principles and highlights how topological effects can be realized in photonic crystals, coupled resonators, metamaterials and quasicrystals.

Lu, Ling; Joannopoulos, John D.; Solja?i?, Marin

2014-11-01

101

Fractional charges and Misner-Wheeler charge without charge effect in metamaterials

Optical space in metamaterials may be engineered to emulate four dimensional Kaluza-Klein theory. Nonlinear optics of such metamaterials mimics interaction of quantized electric charges. An electromagnetic wormhole is designed, which connects two points of such an optical space and changes its effective topology. Electromagnetic field configurations which exhibit fractional charges appear as a result of such topology change. Moreover, such effects as Misner-Wheeler charge without charge may be replicated.

Igor I. Smolyaninov

2014-12-08

102

The HTMCGC collaboration has been simulating lattice QCD with two light staggered quarks with masses m{sub q} = 0.0125 and also m{sub q} = 0.00625 on a 16{sup 3} {times} 8 lattice. We have been studying the behavior of the transition from hadronic matter to a quark-gluon plasma and the properties of that plasma. We have been measuring entropy densities, Debye and hadronic screening lengths, the spacial string tension and topological susceptibility in addition to the standard order parameters. The HEMCGC collaboration has simulated lattice QCD with two light staggered quarks,m{sub q} = 0.025 and m{sub q} = 0.010 on a 16{sup 3} {times} 32 lattice. We have measured the glueball spectrum and topological susceptibilities for these runs.

Sinclair, D.K.; HEMCGC collaboration; HTMCGC collaboration

1992-11-20

103

The HTMCGC collaboration has been simulating lattice QCD with two light staggered quarks with masses m[sub q] = 0.0125 and also m[sub q] = 0.00625 on a 16[sup 3] [times] 8 lattice. We have been studying the behavior of the transition from hadronic matter to a quark-gluon plasma and the properties of that plasma. We have been measuring entropy densities, Debye and hadronic screening lengths, the spacial string tension and topological susceptibility in addition to the standard order parameters. The HEMCGC collaboration has simulated lattice QCD with two light staggered quarks,m[sub q] = 0.025 and m[sub q] = 0.010 on a 16[sup 3] [times] 32 lattice. We have measured the glueball spectrum and topological susceptibilities for these runs.

Sinclair, D.K.

1992-11-20

104

Topological construction of mesoporous materials

Major advances in the field of ordered mesoporous materials have been achieved in topological structure definition at the meso phase, and macroscale levels (shape and morphology) using molecular control during mesoporous materials synthesis. Examples include the use of block copolymers for the preparation of mesoporous materials with large pore sizes ($?30 nm), the formation of mesoporous silica with 3D periodically

Dongyuan Zhao; Yang Peidong; Huo Qisheng; Chmelka Bradley F; Stucky Galen D

1998-01-01

105

Communication Definitions... general definition

design Natural selection will favour individuals that produce effective signals Of maximum effectivenessCommunication Definitions... general definition "the process of conveying information from a sender

Jones, Ian L.

106

Topological Pumping over a Photonic Fibonacci Quasicrystal

Quasiperiodic lattices have recently been shown to be a non-trivial topological phase of matter. Charge pumping -- one of the hallmarks of topological states of matter -- was recently realized for photons in a one-dimensional (1D) off-diagonal Harper model implemented in a photonic waveguide array. The topologically nontrivial 1D Fibonacci quasicrystal (QC) is expected to facilitate a similar phenomenon, but its discrete nature and lack of pumping parameter hinder the experimental study of such topological effects. In this work we overcome these obstacles by utilizing a family of topologically equivalent QCs which ranges from the Fibonacci QC to the Harper model. Implemented in photonic waveguide arrays, we observe the topological properties of this family, and perform a topological pumping of photons across a Fibonacci QC.

Mor Verbin; Oded Zilberberg; Yoav Lahini; Yaacov E. Kraus; Yaron Silberberg

2014-03-27

107

Measurement-only topological quantum computation.

We remove the need to physically transport computational anyons around each other from the implementation of computational gates in topological quantum computing. By using an anyonic analog of quantum state teleportation, we show how the braiding transformations used to generate computational gates may be produced through a series of topological charge measurements. PMID:18764095

Bonderson, Parsa; Freedman, Michael; Nayak, Chetan

2008-07-01

108

Topological susceptibility in lattice QCD with two flavors of dynamical quarks

NASA Astrophysics Data System (ADS)

We present a study of the topological susceptibility in lattice QCD with two degenerate flavors of dynamical quarks. The topological charge is measured on gauge configurations generated with a renormalization group improved gauge action and a mean field improved clover quark action at three values of ?=6/g2 with four sea quark masses at each ?. The lattice spacings at these ?'s are a~0.22, 0.16 and 0.11 fm at the physical up and down quark mass, which are fixed by the physical ? meson mass. The study is supplemented by simulations of pure SU(3) gauge theory with the same gauge action at 5 values of ? with lattice spacings 0.09 fm<~a<~0.27 fm. We employ a field-theoretic definition of the topological charge together with cooling. For the topological susceptibility in the continuum limit of pure SU(3) gauge theory we obtain ?1/4t=197+13-16 MeV where the error shows statistical and systematic ones added in quadrature. In full QCD ?t at heavy sea quark masses is consistent with that of pure SU(3) gauge theory. A decrease of ?t toward light quark masses, as predicted by the anomalous Ward-Takahashi identity for U(1) chiral symmetry, becomes clearer for smaller lattice spacings. The cross over in the behavior of ?t from heavy to light sea quark masses is discussed.

Ali Khan, A.; Aoki, S.; Burkhalter, R.; Ejiri, S.; Fukugita, M.; Hashimoto, S.; Ishizuka, N.; Iwasaki, Y.; Kanaya, K.; Kaneko, T.; Kuramashi, Y.; Manke, T.; Nagai, K.; Okawa, M.; Shanahan, H. P.; Ukawa, A.; Yoshié, T.

2001-12-01

109

Background and Aims The impact of a fruit tree's architecture on its performance is still under debate, especially with regard to the definition of varietal ideotypes and the selection of architectural traits in breeding programmes. This study aimed at providing proof that a modelling approach can contribute to this debate, by using in silico exploration of different combinations of traits and their consequences on light interception, here considered as one of the key parameters to optimize fruit tree production. Methods The variability of organ geometrical traits, previously described in a bi-parental population, was used to simulate 1- to 5-year-old apple trees (Malus × domestica). Branching sequences along trunks observed during the first year of growth of the same hybrid trees were used to initiate the simulations, and hidden semi-Markov chains previously parameterized were used in subsequent years. Tree total leaf area (TLA) and silhouette to total area ratio (STAR) values were estimated, and a sensitivity analysis was performed, based on a metamodelling approach and a generalized additive model (GAM), to analyse the relative impact of organ geometry and lateral shoot types on STAR. Key Results A larger increase over years in TLA mean and variance was generated by varying branching along trunks than by varying organ geometry, whereas the inverse was observed for STAR, where mean values stabilized from year 3 to year 5. The internode length and leaf area had the highest impact on STAR, whereas long sylleptic shoots had a more significant effect than proleptic shoots. Although the GAM did not account for interactions, the additive effects of the geometrical factors explained >90% of STAR variation, but much less in the case of branching factors. Conclusions This study demonstrates that the proposed modelling approach could contribute to screening architectural traits and their relative impact on tree performance, here viewed through light interception. Even though trait combinations and antagonism will need further investigation, the approach opens up new perspectives for breeding and genetic selection to be assisted by varietal ideotype definition. PMID:24723446

Da Silva, David; Han, Liqi; Faivre, Robert; Costes, Evelyne

2014-01-01

110

By use of the quantum theory of atoms in molecules, it was found that the electronic charge distribution rho(r) of the metal atoms in Mn(III), Fe(III), and Co(III) complexes of 8-hydroxyquinoline (8HQ) showed eight nonbonded concentrations in their valence shell that were located at the corners of a cube and a depletion region was located in each of its six faces. Coordination was such that regions of charge concentration of the ligands matched the depletion ones of the metal. The O- and N-metal bonds showed low rho(r(c)) values at the bond critical point r(c) and low and positive ones for its Laplacian indicating that they were dative bonds of close shell type with a degree of covalency. Most changes in rho(r) were located around the N and O atoms of 8HQ directly involved in dative bonds. By use of the delocalization index delta(C(A),C(B)) only for C-C bonds, it was found that coordination increased the aromaticity of most of them. The most important changes in rho(r) were found in the C-H bonds were a noticeable increase in bond strength was obtained upon coordination. PMID:19351130

Murgich, Juan; Franco, Héctor J

2009-04-30

111

112

Band structure engineering in topological insulator based heterostructures.

The ability to engineer an electronic band structure of topological insulators would allow the production of topological materials with tailor-made properties. Using ab initio calculations, we show a promising way to control the conducting surface state in topological insulator based heterostructures representing an insulator ultrathin films on the topological insulator substrates. Because of a specific relation between work functions and band gaps of the topological insulator substrate and the insulator ultrathin film overlayer, a sizable shift of the Dirac point occurs resulting in a significant increase in the number of the topological surface state charge carriers as compared to that of the substrate itself. Such an effect can also be realized by applying the external electric field that allows a gradual tuning of the topological surface state. A simultaneous use of both approaches makes it possible to obtain a topological insulator based heterostructure with a highly tunable topological surface state. PMID:24274792

Menshchikova, T V; Otrokov, M M; Tsirkin, S S; Samorokov, D A; Bebneva, V V; Ernst, A; Kuznetsov, V M; Chulkov, E V

2013-01-01

113

Charge varying sine-Gordon deformed defects

Sine-Gordon deformed defects that exhibit unusual phenomenological features on the topological charge are investigated. The possibility of a smooth and continuous transition between topological (non null charge) and non-topological (null charge) scenarios of deformed defects supported by sine-Gordon structures is evinced by the analytical calculation of topological charges and localized energy distributions. By describing cyclic deformation chains, we show that a triggering sine-Gordon model simultaneously supports kink and lump-like defects, whose topological mass values are closed by trigonometric or hyperbolic successive deformations. In spite of preserving analytical closure relations constraining the topological masses of $3$-and $4$-cyclically deformed defects, the deformation chains produce kinks and lumps which exhibit non-monotonic behavior and extra inflection points, respectively. The outcome of our analysis suggests that cyclic deformations create novel scenarios of physical and mathematical applicability of defect structures supported by the sine-Gordon theory.

Alex E. Bernardini; Mariana Chinaglia; Roldao da Rocha

2014-06-18

114

Topological Aspects of Information Retrieval.

ERIC Educational Resources Information Center

Discusses topological aspects of theoretical information retrieval, including retrieval topology; similarity topology; pseudo-metric topology; document spaces as topological spaces; Boolean information retrieval as a subsystem of any topological system; and proofs of theorems. (LRW)

Egghe, Leo; Rousseau, Ronald

1998-01-01

115

NSDL National Science Digital Library

In this activity, learners construct three math puzzles out of simple materials like wood, string, and Styrofoam. The first two puzzles, called "Remove the Loop" and "Two Washers," are examples of topology, an area of math about how geometric figures are different and similar. The third puzzle, "Towers of Hanoi," uses a mathematical tool called an algorithm and is also a good example of an exponential function.

2014-09-12

116

Topological electronic structure in half-Heusler topological insulators

NASA Astrophysics Data System (ADS)

We have investigated band structures of a series of 28 ternary half-Heusler compounds MM'X of MgAgAs type, where M=(Lu,La,Sc,Y) and M'X=(PtBi,AuPb,PdBi,PtSb,AuSn,NiBi,PdSb) . Our results show that the Z2 topological order is due to a single band inversion at the ? point. In native states, these half-Heusler compounds are identified as being topologically nontrivial semimetals, or nontrivial metals, or trivial insulators, which can be turned into insulating thin films on suitable substrates. Our analysis reveals a straightforward relationship which connects the band inversion strength (extent of deviation from the critical point) to the atomic charge of constituents and the lattice parameter. Our findings suggest a general method for identifying Z2 topological insulators in nonmagnetic ternary compounds.

Al-Sawai, W.; Lin, Hsin; Markiewicz, R. S.; Wray, L. A.; Xia, Y.; Xu, S.-Y.; Hasan, M. Z.; Bansil, A.

2010-09-01

117

Black Holes, q-Deformed 2d Yang-Mills, and Non-perturbative Topological Strings

We count the number of bound states of BPS black holes on local Calabi-Yau three-folds involving a Riemann surface of genus g. We show that the corresponding gauge theory on the brane reduces to a q-deformed Yang-Mills theory on the Riemann surface. Following the recent connection between the black hole entropy and the topological string partition function, we find that for a large black hole charge N, up to corrections of O(e^-N), Z_BH is given as a sum of a square of chiral blocks, each of which corresponds to a specific D-brane amplitude. The leading chiral block, the vacuum block, corresponds to the closed topological string amplitudes. The sub-leading chiral blocks involve topological string amplitudes with D-brane insertions at 2g-2 points on the Riemann surface analogous to the Omega points in the large N 2d Yang-Mills theory. The finite N amplitude provides a non-perturbative definition of topological strings in these backgrounds. This also leads to a novel non-perturbative formulation of c=1 non-critical string at the self-dual radius.

Aganagic, Mina; Ooguri, Hirosi; Saulina, Natalia; Vafa, Cumrun

2005-01-28

118

Topological BF field theory description of topological insulators

Research Highlights: > We show that a BF theory is the effective theory of 2D and 3D topological insulators. > The non-gauge-invariance of the bulk theory yields surface terms for a bosonized Dirac fermion. > The 'axion' term in electromagnetism is correctly obtained from gapped surfaces. > Generalizations to possible fractional phases are discussed in closing. - Abstract: Topological phases of matter are described universally by topological field theories in the same way that symmetry-breaking phases of matter are described by Landau-Ginzburg field theories. We propose that topological insulators in two and three dimensions are described by a version of abelian BF theory. For the two-dimensional topological insulator or quantum spin Hall state, this description is essentially equivalent to a pair of Chern-Simons theories, consistent with the realization of this phase as paired integer quantum Hall effect states. The BF description can be motivated from the local excitations produced when a {pi} flux is threaded through this state. For the three-dimensional topological insulator, the BF description is less obvious but quite versatile: it contains a gapless surface Dirac fermion when time-reversal-symmetry is preserved and yields 'axion electrodynamics', i.e., an electromagnetic E . B term, when time-reversal symmetry is broken and the surfaces are gapped. Just as changing the coefficients and charges of 2D Chern-Simons theory allows one to obtain fractional quantum Hall states starting from integer states, BF theory could also describe (at a macroscopic level) fractional 3D topological insulators with fractional statistics of point-like and line-like objects.

Cho, Gil Young [Department of Physics, University of California, Berkeley, CA 94720 (United States); Moore, Joel E., E-mail: jemoore@berkeley.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2011-06-15

119

NASA Astrophysics Data System (ADS)

The Aharonov-Bohm effect is often called "topological." But it seems no more topological than magnetostatics, electrostatics or Newton-Poisson gravity (or just about any radiation, propagation from a source). I distinguish between two senses of "topological."

Afriat, Alexander

2013-03-01

120

Topological Black Holes -- Outside Looking In

I describe the general mathematical construction and physical picture of topological black holes, which are black holes whose event horizons are surfaces of non-trivial topology. The construction is carried out in an arbitrary number of dimensions, and includes all known special cases which have appeared before in the literature. I describe the basic features of massive charged topological black holes in $(3+1)$ dimensions, from both an exterior and interior point of view. To investigate their interiors, it is necessary to understand the radiative falloff behaviour of a given massless field at late times in the background of a topological black hole. I describe the results of a numerical investigation of such behaviour for a conformally coupled scalar field. Significant differences emerge between spherical and higher genus topologies.

R. B. Mann

1997-09-15

121

Topological susceptibility with the improved Asqtad action

As a test of the chiral properties of the improved Asqtad (staggered fermion) action, we have been measuring the topological susceptibility as a function of quark masses for 2 + 1 dynamical flavors. We report preliminary results, which show reasonable agreement with leading order chiral perturbation theory for lattice spacing less than 0.1 fm. The total topological charge, however, shows strong persistence over Monte Carlo time.

C. Bernard et al.

2004-01-06

122

Topological susceptibility in SU(3) gauge theory.

We compute the topological susceptibility for the SU(3) Yang-Mills theory by employing the expression of the topological charge density operator suggested by Neuberger's fermions. In the continuum limit we find r(4)(0)chi = 0.059(3), which corresponds to chi = (191 +/- 5 MeV)(4) if F(K) is used to set the scale. Our result supports the Witten-Veneziano explanation for the large mass of the eta('). PMID:15698253

Del Debbio, Luigi; Giusti, Leonardo; Pica, Claudio

2005-01-28

123

Observation of unconventional quantum spin textures in topological insulators.

A topologically ordered material is characterized by a rare quantum organization of electrons that evades the conventional spontaneously broken symmetry-based classification of condensed matter. Exotic spin-transport phenomena, such as the dissipationless quantum spin Hall effect, have been speculated to originate from a topological order whose identification requires a spin-sensitive measurement, which does not exist to this date in any system. Using Mott polarimetry, we probed the spin degrees of freedom and demonstrated that topological quantum numbers are completely determined from spin texture-imaging measurements. Applying this method to Sb and Bi(1-x)Sb(x), we identified the origin of its topological order and unusual chiral properties. These results taken together constitute the first observation of surface electrons collectively carrying a topological quantum Berry's phase and definite spin chirality, which are the key electronic properties component for realizing topological quantum computing bits with intrinsic spin Hall-like topological phenomena. PMID:19213915

Hsieh, D; Xia, Y; Wray, L; Qian, D; Pal, A; Dil, J H; Osterwalder, J; Meier, F; Bihlmayer, G; Kane, C L; Hor, Y S; Cava, R J; Hasan, M Z

2009-02-13

124

Extracting Physics from Topologically Frozen Markov Chains

In Monte Carlo simulations with a local update algorithm, the auto-correlation with respect to the topological charge tends to become very long. In the extreme case one can only perform reliable measurements within fixed sectors. We investigate approaches to extract physical information from such topologically frozen simulations. Recent results in a set of sigma-models and gauge theories are encouraging. In a suitable regime, the correct value of some observable can be evaluated to a good accuracy. In addition there are ways to estimate the value of the topological susceptibility.

Urs Gerber; Irais Bautista; Wolfgang Bietenholz; Héctor Mejía-Díaz; Christoph P. Hofmann

2014-10-02

125

Topological and geometric decomposition of nematic textures.

Directional media, such as nematic liquid crystals and ferromagnets, are characterized by their topologically stabilized defects in directional order. In nematics, boundary conditions and surface-treated inclusions often create complex structures, which are difficult to classify. Topological charge of point defects in nematics has ambiguously defined sign, and its additivity cannot be ensured when defects are observed separately. We demonstrate how the topological charge of complex defect structures can be determined by identifying and counting parts of the texture that satisfy simple geometric rules. We introduce a parameter called the defect rank and show that it corresponds to what is intuitively perceived as a point charge based on the properties of the director field. Finally, we discuss the role of free-energy constraints in the validity of the classification with the defect rank. PMID:22587108

Copar, Simon; Zumer, Slobodan

2012-03-01

126

K-theory and Ramond-Ramond charge

We discuss the relation between the Ramond-Ramond charges of D-branes and the topology of Chan-Paton vector bundles. We show that a topologically nontrivial normal bundle induces RR charge and that the result fits in perfectly with the proposal that D-brane charge is the topology of the Chan-Paton bundle, regarded as an element of K-theory.

Ruben Minasian; Gregory Moore

1997-01-01

127

Orbifolds and Topological Defects

NASA Astrophysics Data System (ADS)

We study orbifolds of two-dimensional topological field theories using defects. If the TFT arises as the twist of a superconformal field theory, we recover results on the Neveu-Schwarz and Ramond sectors of the orbifold theory, as well as bulk-boundary correlators from a novel, universal perspective. This entails a structure somewhat weaker than ordinary TFT, which however still describes a sector of the underlying conformal theory. The case of B-twisted Landau-Ginzburg models is discussed in detail, where we compute charge vectors and superpotential terms for B-type branes. Our construction also works in the absence of supersymmetry and for generalised "orbifolds" that need not arise from symmetry groups. In general, this involves a natural appearance of Hochschild (co)homology in a 2-categorical setting, in which among other things we provide simple presentations of Serre functors and a further generalisation of the Cardy condition.

Brunner, Ilka; Carqueville, Nils; Plencner, Daniel

2014-12-01

128

Topological magnetoelectric effect decay.

We address the influence of realistic disorder and finite doping on the effective magnetic monopole induced near the surface of an ideal topological insulator (TI) by currents that flow in response to a suddenly introduced external electric charge. We show that when the longitudinal conductivity ?(xx)=g(e(2)/h)?0, the apparent position of a magnetic monopole initially retreats from the TI surface at speed v(M)=?cg, where ? is the fine structure constant and c is the speed of light. For the particular case of TI surface states described by a massive Dirac model, we further find that the temperature T=0 Hall currents vanish when the external potential is screened. PMID:23863019

Pesin, D A; MacDonald, A H

2013-07-01

129

Interpretation of topologically restricted measurements in lattice sigma-models

We consider models with topological sectors, and difficulties with their Monte Carlo simulation. In particular we are concerned with the situation where a simulation has an extremely long auto-correlation time with respect to the topological charge. Then reliable numerical measurements are possible only within single topological sectors. The challenge is to assemble such restricted measurements to obtain an approximation for the full-fledged result, which corresponds to the correct sampling over the entire set of configurations. Under certain conditions this is possible, and it provides in addition an estimate for the topological susceptibility chi_t. Moreover, the evaluation of chi_t might be feasible even from data in just one topological sector, based on the correlation of the topological charge density. Here we present numerical test results for these techniques in the framework of non-linear sigma-models.

Irais Bautista; Wolfgang Bietenholz; Urs Gerber; Christoph P. Hofmann; Héctor Mejía-Díaz; Lilian Prado

2014-02-11

130

Topological insulators and superconductors from string theory

Topological insulators and superconductors in different spatial dimensions and with different discrete symmetries have been fully classified recently, revealing a periodic structure for the pattern of possible types of topological insulators and superconductors, both in terms of spatial dimensions and in terms of symmetry classes. It was proposed that K theory is behind the periodicity. On the other hand, D-branes, a solitonic object in string theory, are also known to be classified by K theory. In this paper, by inspecting low-energy effective field theories realized by two parallel D-branes, we establish a one-to-one correspondence between the K-theory classification of topological insulators/superconductors and D-brane charges. In addition, the string theory realization of topological insulators and superconductors comes naturally with gauge interactions, and the Wess-Zumino term of the D-branes gives rise to a gauge field theory of topological nature, such as ones with the Chern-Simons term or the {theta} term in various dimensions. This sheds light on topological insulators and superconductors beyond noninteracting systems, and the underlying topological field theory description thereof. In particular, our string theory realization includes the honeycomb lattice Kitaev model in two spatial dimensions, and its higher-dimensional extensions. Increasing the number of D-branes naturally leads to a realization of topological insulators and superconductors in terms of holography (AdS/CFT).

Ryu, Shinsei; Takayanagi, Tadashi [Department of Physics, University of California, Berkeley, California 94720 (United States); Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwa, Chiba 277-8582 (Japan)

2010-10-15

131

Deficient topological measures and functionals generated by them

This paper looks at the properties of deficient topological measures, which are a generalization of topological measures. Integration of a real function that is continuous on a compact set with respect to a deficient topological measure is also investigated. The notions of r- and l-functionals are introduced and an analogue of the Riesz representation theorem is obtained for them. As corollaries, both well-known and new results for quasi-integrals and topological measures are presented (for example, a new version of the definition of a quasi-integral). Bibliography: 16 titles.

Svistula, Marina G [Samara State University, Samara (Russian Federation)

2013-05-31

132

Witten-Nester energy in topologically massive gravity

We formulate topologically massive supergravity with a cosmological constant in the first-order formalism and construct the Noether supercurrent and superpotential associated with its local supersymmetry. Using these results, we construct in ordinary topologically massive gravity the Witten-Nester integral for conserved charges containing spinors which satisfy a generalized version of the Witten equation on the initial value surface. We show that

Ergin Sezgin; Yoshiaki Tanii

2009-01-01

133

LETTER TO THE EDITOR: Energy in topologically massive gravity

We define conserved gravitational charges in cosmologically extended topologically massive gravity, exhibit them in surface integral form about their de Sitter or flat vacua and verify their correctness in terms of two basic types of solution.

S. Deser; Bayram Tekin

2003-01-01

134

12 CFR 226.4 - Finance charge.

Code of Federal Regulations, 2012 CFR

...Section 226.4 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) General § 226.4 Finance charge. (a) Definition. The finance charge is...

2012-01-01

135

12 CFR 226.4 - Finance charge.

Code of Federal Regulations, 2011 CFR

...Section 226.4 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) General § 226.4 Finance charge. (a) Definition. The finance charge is...

2011-01-01

136

- criticality of topological black holes in Lovelock-Born-Infeld gravity

NASA Astrophysics Data System (ADS)

To understand the effect of third order Lovelock gravity, - criticality of topological AdS black holes in Lovelock-Born-Infeld gravity is investigated. The thermodynamics is further explored with some more extensions and in some more detail than the previous literature. A detailed analysis of the limit case is performed for the seven-dimensional black holes. It is shown that, for the spherical topology, - criticality exists for both the uncharged and the charged cases. Our results demonstrate again that the charge is not the indispensable condition of - criticality. It may be attributed to the effect of higher derivative terms of the curvature because similar phenomenon was also found for Gauss-Bonnet black holes. For , there would be no - criticality. Interesting findings occur in the case , in which positive solutions of critical points are found for both the uncharged and the charged cases. However, the - diagram is quite strange. To check whether these findings are physical, we give the analysis on the non-negative definiteness condition of the entropy. It is shown that, for any nontrivial value of , the entropy is always positive for any specific volume . Since no - criticality exists for in Einstein gravity and Gauss-Bonnet gravity, we can relate our findings with the peculiar property of third order Lovelock gravity. The entropy in third order Lovelock gravity consists of extra terms which are absent in the Gauss-Bonnet black holes, which makes the critical points satisfy the constraint of non-negative definiteness condition of the entropy. We also check the Gibbs free energy graph and "swallow tail" behavior can be observed. Moreover, the effect of nonlinear electrodynamics is also included in our research.

Mo, Jie-Xiong; Liu, Wen-Biao

2014-04-01

137

Knots in charged polymers Paul G. Dommersnes,1,2,

The interplay of topological constraints and Coulomb interactions in static and dynamic properties of charged, the long-range interaction localizes irreducible topological constraints into tight molecular knots, while to topological constraints. These constraints can be temporary, such as entanglements between linear polymers

Kantor, Yacov

138

Fractional topological insulators in three dimensions.

Topological insulators can be generally defined by a topological field theory with an axion angle ? of 0 or ?. In this work, we introduce the concept of fractional topological insulator defined by a fractional axion angle and show that it can be consistent with time reversal T invariance if ground state degeneracies are present. The fractional axion angle can be measured experimentally by the quantized fractional bulk magnetoelectric polarization P?, and a "halved" fractional quantum Hall effect on the surface with Hall conductance of the form ?H=p/q e²/2h with p, q odd. In the simplest of these states the electron behaves as a bound state of three fractionally charged "quarks" coupled to a deconfined non-Abelian SU(3) "color" gauge field, where the fractional charge of the quarks changes the quantization condition of P? and allows fractional values consistent with T invariance. PMID:21231552

Maciejko, Joseph; Qi, Xiao-Liang; Karch, Andreas; Zhang, Shou-Cheng

2010-12-10

139

Sufficient symmetry conditions for Topological Quantum Order

We prove sufficient conditions for Topological Quantum Order at zero and finite temperatures. The crux of the proof hinges on the existence of low-dimensional Gauge-Like Symmetries, thus providing a unifying framework based on a symmetry principle. These symmetries may be actual invariances of the system, or may emerge in the low-energy sector. Prominent examples of Topological Quantum Order display Gauge-Like Symmetries. New systems exhibiting such symmetries include Hamiltonians depicting orbital-dependent spin exchange and Jahn–Teller effects in transition metal orbital compounds, short-range frustrated Klein spin models, and p+ip superconducting arrays. We analyze the physical consequences of Gauge-Like Symmetries (including topological terms and charges) and show the insufficiency of the energy spectrum, topological entanglement entropy, maximal string correlators, and fractionalization in establishing Topological Quantum Order. General symmetry considerations illustrate that not withstanding spectral gaps, thermal fluctuations may impose restrictions on suggested quantum computing schemes. Our results allow us to go beyond standard topological field theories and engineer systems with Topological Quantum Order. PMID:19805113

Nussinov, Zohar; Ortiz, Gerardo

2009-01-01

140

Periodic table for topological insulators and superconductors

Gapped phases of noninteracting fermions, with and without charge conservation and time-reversal symmetry, are classified using Bott periodicity. The symmetry and spatial dimension determines a general universality class, which corresponds to one of the 2 types of complex and 8 types of real Clifford algebras. The phases within a given class are further characterized by a topological invariant, an element

Alexei Kitaev; Alexei

2009-01-01

141

Genetics Home Reference: CHARGE syndrome

... Patients and Families Resources for Health Professionals What glossary definitions help with understanding CHARGE syndrome? anosmia ; atresia ; ... many other terms in the Genetics Home Reference Glossary . See also Understanding Medical Terminology . References (6 links) ...

142

Boundaries and Topological Algorithms

This thesis develops a model for the topological structure of situations. In this model, the topological structure of space is altered by the presence or absence of boundaries, such as those at the edges of objects. ...

Fleck, Margaret Morrison

1988-09-01

143

Topological and Error-Correcting Properties for Symmetry-Protected Topological Order

We discuss the symmetry-protected topological (SPT) orders for bosonic systems from an information-theoretic viewpoint. We show that with a proper choice of the onsite basis, the degenerate ground-state space of SPT orders (on a manifold with boundary) is a quantum error-correcting code with macroscopic classical distance, hence is stable against any local bit-flip errors. We show that this error-correcting property of the SPT orders has a natural connection to that of the symmetry-breaking orders, whose degenerate ground-state space is a classical error-correcting code with a macroscopic distance, providing a new angle for the hidden symmetry-breaking properties in SPT orders. We propose new types of topological entanglement entropy that probe the STP orders hidden in their symmetric ground states, which also signal the topological phase transitions protected by symmetry. Combined with the original definition of topological entanglement entropy that probes the 'intrinsic topological orders', and the recent proposed one that probes the symmetry-breaking orders, the set of different types of topological entanglement entropy may hence distinguish topological orders, SPT orders, and symmetry-breaking orders, which may be mixed up in a single system.

Bei Zeng; Duan-Lu Zhou

2014-07-12

144

Vortex Motion In Charged Fluids

A non-relativistic scalar field coupled minimally to electromagnetism supports in the presence of a homogeneous background electric charge density the existence of smooth, finite-energy topologically stable flux vortices. The static properties of such vortices are studied numerically in the context of a two parameter model describing this system as a special case. It is shown that the electrostatic and the mexican hat potential terms of the energy are each enough to ensure the existence of vortex solutions. The interaction potential of two minimal vortices is obtained for various values of the parameters. It is proven analytically that a free isolated vortex with topological charge $N\

G. N. Stratopoulos; T. N. Tomaras

1994-05-18

145

Virasoro constraints and flavor-topology duality in QCD

We derive Virasoro constraints for the zero momentum part of the QCD-like partition functions in the sector of topological charge {nu}. The constraints depend on the topological charge only through the combination N{sub f}+{beta}{nu}/2 where the value of the Dyson index {beta} is determined by the reality type of the fermions. This duality between flavor and topology is inherited by the small-mass expansion of the partition function and all spectral sum rules of inverse powers of the eigenvalues of the Dirac operator. For the special case {beta}=2 but arbitrary topological charge the Virasoro constraints are solved uniquely by a generalized Kontsevich model with the potential V(X)=1/X.

Dalmazi, D.; Verbaarschot, J. J. M.

2001-09-01

146

NASA Technical Reports Server (NTRS)

This thesis addresses the acoustoelectric issues concerning the amplification of surface acoustic waves (SAWs) and the reflection of SAWs from slanted reflector gratings on GaAs, with application to a novel acoustic charge transport (ACT) device architecture. First a simple model of the SAWAMP was developed, which was subsequently used to define the epitaxially grown material structure necessary to provide simultaneously high resistance and high electron mobility. In addition, a segmented SAWAMP structure was explored with line widths on the order of an acoustic wavelength. This resulted in the demonstration of SAWAMPS with an order of magnitude less voltage and power requirements than previously reported devices. A two-dimensional model was developed to explain the performance of devices with charge confinement layers less then 0.5 mm, which was experimentally verified. This model was extended to predict a greatly increased gain from the addition of a ZnO overlay. These overlays were experimentally attempted, but no working devices were reported due to process incompatibilities. In addition to the SAWAMP research, the reflection of SAWs from slanted gratings on GaAs was also studied and experimentally determined reflection coefficients for both 45 deg grooves and Al stripes on GaAs have been reported for the first time. The SAWAMp and reflector gratings were combined to investigate the integrated ring oscillator for application to the proposed ACT device and design parameters for this device have been provided.

Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Cameron, Thomas P.

1996-01-01

147

148

Code of Federal Regulations, 2010 CFR

... § 7.4001 Charging interest at rates permitted competing institutions; charging interest to corporate borrowers...Definition. The term “interest” as used in 12 U...includes, among other things, the...

2010-01-01

149

Code of Federal Regulations, 2013 CFR

... § 7.4001 Charging interest at rates permitted competing institutions; charging interest to corporate borrowers...Definition. The term “interest” as used in 12 U...includes, among other things, the...

2013-01-01

150

Code of Federal Regulations, 2012 CFR

... § 7.4001 Charging interest at rates permitted competing institutions; charging interest to corporate borrowers...Definition. The term “interest” as used in 12 U...includes, among other things, the...

2012-01-01

151

Code of Federal Regulations, 2011 CFR

2011-01-01

152

Game Theory and Topological Phase Transition

Phase transition is a war game. It widely exists in different kinds of complex system beyond physics. Where there is revolution, there is phase transition. The renormalization group transformation, which was proved to be a powerful tool to study the critical phenomena, is actually a game process. The phase boundary between the old phase and new phase is the outcome of many rounds of negotiation between the old force and new force. The order of phase transition is determined by the cutoff of renormalization group transformation. This definition unified Ehrenfest's definition of phase transition in thermodynamic physics. If the strategy manifold has nontrivial topology, the topological relation would put a constrain on the surviving strategies, the transition occurred under this constrain may be called a topological one. If the strategy manifold is open and noncompact, phase transition is simply a game process, there is no table for topology. An universal phase coexistence equation is found, it sits at the Nash equilibrium point. Inspired by the fractal space structure demonstrated by renormalization group theory, a conjecture is proposed that the universal scaling law of a general phase transition in a complex system comes from the coexistence equation around Nash equilibrium point. Game theory also provide us new understanding to pairing mechanism and entanglement in many body physics.

Tieyan Si

2006-01-02

153

Topological structure of the SU(3) vacuum

NASA Astrophysics Data System (ADS)

We investigate the topological structure of the vacuum in SU(3) lattice gauge theory. We use under-relaxed cooling to remove the high-frequency fluctuations and a variety of ``filters'' to identify the topological charges in the resulting smoothened field configurations. We find a densely packed vacuum with an average instanton size, in the continuum limit, of ?¯~0.5 fm. The density at large ? decreases rapidly as 1/?~11. At small sizes we see some signs of a trend towards the asymptotic perturbative behavior of D(?)~?6. We find that an interesting polarization phenomenon occurs: the large topological charges tend to have, on the average, the same sign and are over-screened by the smaller charges which tend to have, again on the average, the opposite sign to the larger instantons. We also calculate the topological susceptibility, ?t, for which we obtain a continuum value of ?1/4t~187 MeV. We perform the calculations for various volumes, lattice spacings and numbers of cooling sweeps, so as to obtain some control over the associated systematic errors. The coupling range is 6.0<=?<=6.4 and the lattice volumes range from 163×48 to 323×64.

Smith, Douglas A.; Teper, Michael J.

1998-07-01

154

Emerging high-bandwidth, low-latency network technology has made network-based architectures both feasible and potentially desirable for use in satellite payload architectures. The selection of network topology is a critical component when developing these multi-node or multi-point architectures. This study examines network topologies and their effect on overall network performance. Numerous topologies were reviewed against a number of performance, reliability, and cost metrics. This document identifies a handful of good network topologies for satellite applications and the metrics used to justify them as such. Since often multiple topologies will meet the requirements of the satellite payload architecture under development, the choice of network topology is not easy, and in the end the choice of topology is influenced by both the design characteristics and requirements of the overall system and the experience of the developer.

Kalb, Jeffrey L.; Lee, David S.

2008-01-01

155

A new class of non-topological solitons

NASA Technical Reports Server (NTRS)

A class of non-topological solitons was constructed in renormalizable scalar field theories with nonlinear self-interactions. For large charge Q, the soliton mass increases linearly with Q, i.e., the soliton mass density is approximately independent of charge. Such objects could be naturally produced in a phase transition in the early universe or in the decay of superconducting cosmic strings.

Frieman, Joshua A.; Lynn, Bryan W.

1989-01-01

156

Photonic Floquet topological insulators.

Topological insulators are a new phase of matter, with the striking property that conduction of electrons occurs only on their surfaces. In two dimensions, electrons on the surface of a topological insulator are not scattered despite defects and disorder, providing robustness akin to that of superconductors. Topological insulators are predicted to have wide-ranging applications in fault-tolerant quantum computing and spintronics. Substantial effort has been directed towards realizing topological insulators for electromagnetic waves. One-dimensional systems with topological edge states have been demonstrated, but these states are zero-dimensional and therefore exhibit no transport properties. Topological protection of microwaves has been observed using a mechanism similar to the quantum Hall effect, by placing a gyromagnetic photonic crystal in an external magnetic field. But because magnetic effects are very weak at optical frequencies, realizing photonic topological insulators with scatter-free edge states requires a fundamentally different mechanism-one that is free of magnetic fields. A number of proposals for photonic topological transport have been put forward recently. One suggested temporal modulation of a photonic crystal, thus breaking time-reversal symmetry and inducing one-way edge states. This is in the spirit of the proposed Floquet topological insulators, in which temporal variations in solid-state systems induce topological edge states. Here we propose and experimentally demonstrate a photonic topological insulator free of external fields and with scatter-free edge transport-a photonic lattice exhibiting topologically protected transport of visible light on the lattice edges. Our system is composed of an array of evanescently coupled helical waveguides arranged in a graphene-like honeycomb lattice. Paraxial diffraction of light is described by a Schrödinger equation where the propagation coordinate (z) acts as 'time'. Thus the helicity of the waveguides breaks z-reversal symmetry as proposed for Floquet topological insulators. This structure results in one-way edge states that are topologically protected from scattering. PMID:23579677

Rechtsman, Mikael C; Zeuner, Julia M; Plotnik, Yonatan; Lumer, Yaakov; Podolsky, Daniel; Dreisow, Felix; Nolte, Stefan; Segev, Mordechai; Szameit, Alexander

2013-04-11

157

Model for Topological Fermions

NASA Astrophysics Data System (ADS)

We introduce a model designed to describe charged particles as stable topological solitons of a field with values on the internal space S3. These solitons behave like particles with relativistic properties like Lorentz contraction and velocity dependence of mass. This mass is defined by the energy of the soliton. In this sense this model is a generalization of the Sine-Gordon model1(We do not chase the aim to give a four-dimensional generalization of Coleman's isomorphism between the Sine-Gordon model and the Thirring model which was shown in 2-dimensional space-time) from 1+1-dimensions to 3+1-dimensions, from S1 to S3. For large distances from the centre of solitons this model tends to a dual U(1)-theory with freely propagating electromagnetic waves. Already at the classical level it describes important effects, which usually have to be explained by quantum field theory, like particle-antiparticle annihilation and the running of the coupling.

Faber, M.

158

Influence of autocorrelation on the topology of the climate network

NASA Astrophysics Data System (ADS)

Different definitions of links in climate networks may lead to considerably different network topologies. We construct a network from climate records of surface level atmospheric temperature in different geographical sites around the globe using two commonly used definitions of links. Utilizing detrended fluctuation analysis, shuffled surrogates, and separation analysis of maritime and continental records, we find that one of the major influences on the structure of climate networks is due to the autocorrelation in the records, which may introduce spurious links. This may explain why different methods could lead to different climate network topologies.

Guez, Oded C.; Gozolchiani, Avi; Havlin, Shlomo

2014-12-01

159

Influence of autocorrelation on the topology of the climate network

Different definitions of links in climate networks may lead to considerably different network topologies. We construct a network from climate records of surface level atmospheric temperature in different geographical sites around the globe using two commonly used definitions of links. Utilizing detrended fluctuation analysis, shuffled surrogates and separation analysis of maritime and continental records, we find that one of the major influences on the structure of climate networks is due to the auto-correlation in the records, that may introduce spurious links. This may explain why different methods could lead to different climate network topologies.

Guez, Oded C; Havlin, Shlomo

2014-01-01

160

Diagnosing deconfinement and topological order

NASA Astrophysics Data System (ADS)

Topological or deconfined phases are characterized by emergent, weakly fluctuating, gauge fields. In condensed matter settings, they inevitably come coupled to excitations that carry the corresponding gauge charges which invalidate the standard diagnostic of deconfinement—the Wilson loop. Inspired by a mapping between symmetric sponges and the deconfined phase of the Z2 gauge theory, we construct a diagnostic for deconfinement that has the interpretation of a line tension. One operator version of this diagnostic turns out to be the Fredenhagen-Marcu order parameter known to lattice gauge theorists and we show that a different version is best suited to condensed matter systems. We discuss generalizations of the diagnostic, use it to establish the existence of finite temperature topological phases in d>=3 dimensions and show that multiplets of the diagnostic are useful in settings with multiple phases, such as U(1) gauge theories with charge q matter. (Additionally, we present an exact reduction of the partition function of the toric code in general dimensions to a well-studied problem.)

Gregor, K.; Huse, David A.; Moessner, R.; Sondhi, S. L.

2011-02-01

161

Topological crystalline insulator nanostructures

NASA Astrophysics Data System (ADS)

Topological crystalline insulators are topological insulators whose surface states are protected by the crystalline symmetry, instead of the time reversal symmetry. Similar to the first generation of three-dimensional topological insulators such as Bi2Se3 and Bi2Te3, topological crystalline insulators also possess surface states with exotic electronic properties such as spin-momentum locking and Dirac dispersion. Experimentally verified topological crystalline insulators to date are SnTe, Pb1-xSnxSe, and Pb1-xSnxTe. Because topological protection comes from the crystal symmetry, magnetic impurities or in-plane magnetic fields are not expected to open a gap in the surface states in topological crystalline insulators. Additionally, because they have a cubic structure instead of a layered structure, branched structures or strong coupling with other materials for large proximity effects are possible, which are difficult with layered Bi2Se3 and Bi2Te3. Thus, additional fundamental phenomena inaccessible in three-dimensional topological insulators can be pursued. In this review, topological crystalline insulator SnTe nanostructures will be discussed. For comparison, experimental results based on SnTe thin films will be covered. Surface state properties of topological crystalline insulators will be discussed briefly.

Shen, Jie; Cha, Judy J.

2014-11-01

162

Topological insulators/Isolants topologiques An introduction to topological insulators

Topological insulators/Isolants topologiques An introduction to topological insulators Introduction in the first Brillouin Zone, and their associated energies. In an insulator, an energy gap around the chemical topology, the insulator is called a topological insulator. We introduce this notion of topological order

Paris-Sud XI, UniversitÃ© de

163

NASA Astrophysics Data System (ADS)

We study a topological phase of interacting bosons in (3 +1 ) dimensions that is protected by charge conservation and time-reversal symmetry. We present an explicit lattice model that realizes this phase and that can be studied in sign-free Monte Carlo simulations. The idea behind our model is to bind bosons to topological defects called hedgehogs. We determine the phase diagram of the model and identify a phase where such bound states are proliferated. In this phase, we observe a Witten effect in the bulk whereby an external monopole binds half of the elementary boson charge, which confirms that it is a bosonic topological insulator. We also study the boundary between the topological insulator and a trivial insulator. We find a surface phase diagram that includes exotic superfluids, a topologically ordered phase, and a phase with a Hall effect quantized to one-half of the value possible in a purely two-dimensional system. We also present models that realize symmetry-enriched topologically ordered phases by binding multiple hedgehogs to each boson; these phases show charge fractionalization and intrinsic topological order as well as a fractional Witten effect.

Geraedts, Scott D.; Motrunich, Olexei I.

2014-10-01

164

We study a topological phase of interacting bosons in (3+1) dimensions which is protected by charge conservation and time-reversal symmetry. We present an explicit lattice model which realizes this phase and which can be studied in sign-free Monte Carlo simulations. The idea behind our model is to bind bosons to topological defects called hedgehogs. We determine the phase diagram of the model and identify a phase where such bound states are proliferated. In this phase we observe a Witten effect in the bulk whereby an external monopole binds half of the elementary boson charge, which confirms that it is a bosonic topological insulator. We also study the boundary between the topological insulator and a trivial insulator. We find a surface phase diagram which includes exotic superfluids, a topologically ordered phase, and a phase with a Hall effect quantized to one-half of the value possible in a purely two-dimensional system. We also present models that realize symmetry-enriched topologically-ordered phases by binding multiple hedgehogs to each boson; these phases show charge fractionalization and intrinsic topological order as well as a fractional Witten effect.

Scott Geraedts; Olexei Motrunich

2014-08-05

165

Periodic table for topological insulators and superconductors

Gapped phases of noninteracting fermions, with and without charge conservation and time-reversal symmetry, are classified using Bott periodicity. The symmetry and spatial dimension determines a general universality class, which corresponds to one of the 2 types of complex and 8 types of real Clifford algebras. The phases within a given class are further characterized by a topological invariant, an element of some Abelian group that can be 0, Z, or Z_2. The interface between two infinite phases with different topological numbers must carry some gapless mode. Topological properties of finite systems are described in terms of K-homology. This classification is robust with respect to disorder, provided electron states near the Fermi energy are absent or localized. In some cases (e.g., integer quantum Hall systems) the K-theoretic classification is stable to interactions, but a counterexample is also given.

Alexei Kitaev

2009-01-18

166

Notes on topological insulators

This paper is a survey of the $\\mathbb{Z}/\\mathbb{Z}_2$-valued invariants of topological insulators in condensed matter physics. The $\\mathbb{Z}$-valued topological invariant was originally called the TKNN invariant in physics, which has been fully understood as the first Chern number. The $\\mathbb{Z}_2$ invariant is more mysterious, we will devote our efforts to reviewing its equivalent descriptions from different point of views. We emphasize that both invariants are realizations of the Atiyah--Singer index theorem in condensed matter physics. The topological K-theory also plays an important role in the classification of topological insulators with different symmetries.

Dan Li; Ralph M. Kaufmann; Birgit Wehefritz-Kaufmann

2015-01-13

167

Lipids and topological rules governing membrane protein assembly.

Membrane protein folding and topogenesis are tuned to a given lipid profile since lipids and proteins have co-evolved to follow a set of interdependent rules governing final protein topological organization. Transmembrane domain (TMD) topology is determined via a dynamic process in which topogenic signals in the nascent protein are recognized and interpreted initially by the translocon followed by a given lipid profile in accordance with the Positive Inside Rule. The net zero charged phospholipid phosphatidylethanolamine and other neutral lipids dampen the translocation potential of negatively charged residues in favor of the cytoplasmic retention potential of positively charged residues (Charge Balance Rule). This explains why positively charged residues are more potent topological signals than negatively charged residues. Dynamic changes in orientation of TMDs during or after membrane insertion are attributed to non-sequential cooperative and collective lipid-protein charge interactions as well as long-term interactions within a protein. The proportion of dual topological conformers of a membrane protein varies in a dose responsive manner with changes in the membrane lipid composition not only in vivo but also in vitro and therefore is determined by the membrane lipid composition. Switching between two opposite TMD topologies can occur in either direction in vivo and also in liposomes (designated as fliposomes) independent of any other cellular factors. Such lipid-dependent post-insertional reversibility of TMD orientation indicates a thermodynamically driven process that can occur at any time and in any cell membrane driven by changes in the lipid composition. This dynamic view of protein topological organization influenced by the lipid environment reveals previously unrecognized possibilities for cellular regulation and understanding of disease states resulting from mis-folded proteins. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24341994

Bogdanov, Mikhail; Dowhan, William; Vitrac, Heidi

2014-08-01

168

Topological Pair-Density-Wave Superconducting States

NASA Astrophysics Data System (ADS)

We show that the pair-density-wave (PDW) superconducting state emergent in extended Heisenberg-Hubbard models in two-leg ladders is topological in the presence of an Ising spin symmetry and supports a Majorana zero mode (MZM) at an open boundary and at a junction with a uniform d -wave one-dimensional superconductor. Similarly to a conventional finite-momentum paired state, the order parameter of the PDW state is a charge-2 e field with finite momentum. However, the order parameter here is a quartic electron operator and conventional mean-field theory cannot be applied to study this state. We use bosonization to show that the 1D PDW state has a MZM at a boundary. This superconducting state is an exotic topological phase supporting Majorana fermions with finite-momentum pairing fields and charge-4 e superconductivity.

Cho, Gil Young; Soto-Garrido, Rodrigo; Fradkin, Eduardo

2014-12-01

169

Topological pair-density-wave superconducting States.

We show that the pair-density-wave (PDW) superconducting state emergent in extended Heisenberg-Hubbard models in two-leg ladders is topological in the presence of an Ising spin symmetry and supports a Majorana zero mode (MZM) at an open boundary and at a junction with a uniform d-wave one-dimensional superconductor. Similarly to a conventional finite-momentum paired state, the order parameter of the PDW state is a charge-2e field with finite momentum. However, the order parameter here is a quartic electron operator and conventional mean-field theory cannot be applied to study this state. We use bosonization to show that the 1D PDW state has a MZM at a boundary. This superconducting state is an exotic topological phase supporting Majorana fermions with finite-momentum pairing fields and charge-4e superconductivity. PMID:25554900

Cho, Gil Young; Soto-Garrido, Rodrigo; Fradkin, Eduardo

2014-12-19

170

Colloquium: Topological insulators

NASA Astrophysics Data System (ADS)

Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have protected conducting states on their edge or surface. These states are possible due to the combination of spin-orbit interactions and time-reversal symmetry. The two-dimensional (2D) topological insulator is a quantum spin Hall insulator, which is a close cousin of the integer quantum Hall state. A three-dimensional (3D) topological insulator supports novel spin-polarized 2D Dirac fermions on its surface. In this Colloquium the theoretical foundation for topological insulators and superconductors is reviewed and recent experiments are described in which the signatures of topological insulators have been observed. Transport experiments on HgTe/CdTe quantum wells are described that demonstrate the existence of the edge states predicted for the quantum spin Hall insulator. Experiments on Bi1-xSbx , Bi2Se3 , Bi2Te3 , and Sb2Te3 are then discussed that establish these materials as 3D topological insulators and directly probe the topology of their surface states. Exotic states are described that can occur at the surface of a 3D topological insulator due to an induced energy gap. A magnetic gap leads to a novel quantum Hall state that gives rise to a topological magnetoelectric effect. A superconducting energy gap leads to a state that supports Majorana fermions and may provide a new venue for realizing proposals for topological quantum computation. Prospects for observing these exotic states are also discussed, as well as other potential device applications of topological insulators.

Hasan, M. Z.; Kane, C. L.

2010-10-01

171

Comprehensible Presentation of Topological Information

applications in other topological data analysis settings.based on topological analysis over a data set. Contours, theTopological information has proven very valuable in the analysis of scientific data.

Weber, Gunther H.

2013-01-01

172

A Battery Charger and State of Charge Indicator

NASA Technical Reports Server (NTRS)

A battery charger which has a full wave rectifier in series with a transformer isolated 20 kHz dc-dc converter with high frequency switches, which are programmed to actively shape the input dc line current to be a mirror image of the ac line voltage is discussed. The power circuit operates at 2 kW peak and 1 kW average power. The BC/SCI has two major subsystems: (1) the battery charger power electronics with its controls; and (2) a microcomputer subsystem which is used to acquire battery terminal data and exercise the state of charge software programs. The state of charge definition employed is the energy remaining in the battery when extracted at a 10 kW rate divided by the energy capacity of a fully charged new battery. The battery charger circuit is an isolated boost converter operating at an internal frequency of 20 kHz. The switches selected for the battery charger are the single most important item in determining its efficiency. The combination of voltage and current requirements dictate the use of high power NPN Darlington switching transistors. The power circuit topology is a three switch design which utilizes a power FET on the center tap of the isolation transformer and the power Darlingtons on each of the two ends. An analog control system is employed to accomplish active input current waveshaping as well as the necessary regulation.

Latos, T. S.

1984-01-01

173

Battery charger and state of charge indicator. Final report

The battery charger has a full-wave rectifier in series with a transformer isolated 20 kHz dc-dc converter with high frequency switches which are programmed to actively shape the input ac line current to be a mirror image of the ac line voltage. The power circuit is capable of operating at 2 kW peak and 1 kW average power. The BC/SCI has two major subsystems: (1) the battery charger power electronics with its controls; and (2) a microcomputer subsystem which is used to acquire battery terminal data and exercise the state-of-charge software programs. The state-of-charge definition employed is the energy remaining in the battery when extracted at a 10 kW rate divided by the energy capacity of a fully charged new battery. The battery charger circuit is an isolated boost converter operating at an internal frequency of 20 kHz. The switches selected for the battery charger are the single most important item in determining its efficiency. The combination of voltage and current requirements dictated the use of high power NPN Darlington switching transistors. The power circuit topology developed is a three switch design utilizing a power FET on the center tap of the isolation transformer and the power Darlingtons on each of the two ends. An analog control system is employed to accomplish active input current waveshaping as well as the necessary regulation.

Latos, T.S.

1984-04-15

174

Ground State Degeneracy of Topological Phases on Open Surfaces

We relate the ground state degeneracy (GSD) of a non-Abelian topological phase on a surface with boundaries to the anyon condensates that break the topological phase to a trivial phase. Specifically, we propose that gapped boundary conditions of the surface are in one-to-one correspondence to the sets of condensates, each being able to completely break the phase, and we substantiate this by examples. The GSD resulting from a particular boundary condition coincides with the number of confined topological sectors due to the corresponding condensation. These lead to a generalization of the Laughlin-Wu-Tao (LWT) charge-pumping argument for Abelian fractional quantum Hall states (FQHS) to encompass non-Abelian topological phases, in the sense that an anyon loop of a confined anyon winding a non-trivial cycle can pump a condensate from one boundary to another. Such generalized pumping may find applications in quantum control of anyons, eventually realizing topological quantum computation.

Ling-Yan Hung; Yidun Wan

2014-07-31

175

Experimental Discovery of Topological Insulators and Related Superconductors

Most quantum states of condensed matter are categorized by the symmetries they break. The remarkable discovery of charge Quantum Hall effects (1980s) revealed that there exists an organizational principle of matter based only on the topological distinctions, but in the presence of time-reversal symmetry breaking. In the past few years, theoretical developments suggest that new classes of topological states of matter might exist that are purely topological in nature in the sense that they do not break time-reversal symmetry, and hence can be realized without any applied magnetic field: "Quantum Hall-like effects without Magnetic Fields." This talk describes our discovery of new topologically ordered states of matter (topological insulators) and discusses the unusual electro-magnetic, spin, and superconducting properties this novel phase of quantum matter might exhibit and their potential applications.

Hasan, M. Zahid (Princeton) [Princeton

2010-09-15

176

Destroying a topological quantum bit by condensing Ising vortices

NASA Astrophysics Data System (ADS)

The imminent realization of topologically protected qubits in fabricated systems will provide not only an elementary implementation of fault-tolerant quantum computing architecture, but also an experimental vehicle for the general study of topological order. The simplest topological qubit harbours what is known as a Z2 liquid phase, which encodes information via a degeneracy depending on the system’s topology. Elementary excitations of the phase are fractionally charged objects called spinons, or Ising flux vortices called visons. At zero temperature, a Z2 liquid is stable under deformations of the Hamiltonian until spinon or vison condensation induces a quantum-phase transition destroying the topological order. Here we use quantum Monte Carlo to study a vison-induced transition from a Z2 liquid to a valence-bond solid in a quantum dimer model on the kagome lattice. Our results indicate that this critical point is beyond the description of the standard Landau paradigm.

Hao, Zhihao; Inglis, Stephen; Melko, Roger

2014-12-01

177

Destroying a topological quantum bit by condensing Ising vortices.

The imminent realization of topologically protected qubits in fabricated systems will provide not only an elementary implementation of fault-tolerant quantum computing architecture, but also an experimental vehicle for the general study of topological order. The simplest topological qubit harbours what is known as a Z2 liquid phase, which encodes information via a degeneracy depending on the system's topology. Elementary excitations of the phase are fractionally charged objects called spinons, or Ising flux vortices called visons. At zero temperature, a Z2 liquid is stable under deformations of the Hamiltonian until spinon or vison condensation induces a quantum-phase transition destroying the topological order. Here we use quantum Monte Carlo to study a vison-induced transition from a Z2 liquid to a valence-bond solid in a quantum dimer model on the kagome lattice. Our results indicate that this critical point is beyond the description of the standard Landau paradigm. PMID:25488132

Hao, Zhihao; Inglis, Stephen; Melko, Roger

2014-01-01

178

Topological black holes in Horava-Lifshitz gravity

We find topological (charged) black holes whose horizon has an arbitrary constant scalar curvature 2k in Horava-Lifshitz theory. Without loss of generality, one may take k=1, 0, and -1. The black hole solution is asymptotically anti-de Sitter with a nonstandard asymptotic behavior. Using the Hamiltonian approach, we define a finite mass associated with the solution. We discuss the thermodynamics of the topological black holes and find that the black hole entropy has a logarithmic term in addition to an area term. We find a duality in Hawking temperature between topological black holes in Horava-Lifshitz theory and Einstein's general relativity: the temperature behaviors of black holes with k=1, 0, and -1 in Horava-Lifshitz theory are, respectively, dual to those of topological black holes with k=-1, 0, and 1 in Einstein's general relativity. The topological black holes in Horava-Lifshitz theory are thermodynamically stable.

Cai Ronggen [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China) and Kavli Institute for Theoretical Physics China (KITPC), Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China); Cao Liming [Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Ohta, Nobuyoshi [Department of Physics, Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan)

2009-07-15

179

Topological susceptibility with the asqtad action

Chiral perturbation theory predicts that in quantum chromodynamics (QCD), light dynamical quarks suppress the gauge-field topological susceptibility of the vacuum. The degree of suppression depends on quark multiplicity and masses. It provides a strong consistency test for fermion formulations in lattice QCD. Such tests are especially important for staggered fermion formulations that lack a full chiral symmetry and use the 'fourth-root' procedure to achieve the desired number of sea quarks. Over the past few years we have measured the topological susceptibility on a large database of 18 gauge-field ensembles, generated in the presence of 2+1 flavors of dynamical asqtad quarks with up and down quark masses ranging from 0.05 to 1 in units of the strange quark mass and lattice spacings ranging from 0.045 fm to 0.12 fm. Our study also includes three quenched ensembles with lattice spacings ranging from 0.06 to 0.12 fm. We construct the topological susceptibility from the integrated point-to-point correlator of the discretized topological charge density FF-tilde. To reduce its variance, we model the asymptotic tail of the correlator. The continuum extrapolation of our results for the topological susceptibility agrees nicely at small quark mass with the predictions of lowest-order SU(3) chiral perturbation theory, thus lending support to the validity of the fourth-root procedure.

Bazavov, A.; Toussaint, D. [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Bernard, C.; Laiho, J. [Department of Physics, Washington University, St. Louis, Missouri 63130 (United States); Billeter, B.; DeTar, C.; Levkova, L.; Oktay, M. B. [Physics Department, University of Utah, Salt Lake City, Utah 84112 (United States); Gottlieb, Steven [Department of Physics, Indiana University, Bloomington, Indiana 47405, USA, NCSA, University of Illinois, Urbana, Illinois 61801 (United States); Heller, U. M. [American Physical Society, One Research Road, Ridge, New York 11961 (United States); Hetrick, J. E. [Physics Department, University of the Pacific, Stockton, California 95211 (United States); Osborn, J. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Sugar, R. L. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Van de Water, R. S. [Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2010-06-01

180

Topological Phase Transition without Gap Closing

Topological phase transition is accompanied with a change of topological numbers. According to the bulk-edge correspondence, the gap closing and the breakdown of the adiabaticity are necessary at the phase transition point to make the topological number ill-defined. However, the gap closing is not always needed. In this paper, we show that two topological distinct phases can be continuously connected without gap closing, provided the symmetry of the system changes during the process. Here we propose the generic principles how this is possible by demonstrating various examples such as 1D polyacetylene with the charge-density-wave order, 2D silicene with the antiferromagnetic order, 2D silicene or quantum well made of HgTe with superconducting proximity effects and 3D superconductor Cu doped Bi2Se3. It is argued that such an unusual phenomenon can occur when we detour around the gap closing point provided the connection of the topological numbers is lost along the detour path. PMID:24071900

Ezawa, Motohiko; Tanaka, Yukio; Nagaosa, Naoto

2013-01-01

181

Topological susceptibility with the asqtad action

Chiral perturbation theory predicts that in quantum chromodynamics (QCD), light dynamical quarks suppress the gauge-field topological susceptibility of the vacuum. The degree of suppression depends on quark multiplicity and masses. It provides a strong consistency test for fermion formulations in lattice QCD. Such tests are especially important for staggered fermion formulations that lack a full chiral symmetry and use the 'fourth-root' procedure to achieve the desired number of sea quarks. Over the past few years we have measured the topological susceptibility on a large database of 18 gauge field ensembles, generated in the presence of 2+1 flavors of dynamical asqtad quarks with up and down quark masses ranging from 0.05 to 1 in units of the strange quark mass and lattice spacings ranging from 0.045 fm to 0.12 fm. Our study also includes three quenched ensembles with lattice spacings ranging from 0.06 to 0.12 fm. We construct the topological susceptibility from the integrated point-to-point correlator of the discretized topological charge density F{tilde F}. To reduce its variance, we model the asymptotic tail of the correlator. The continuum extrapolation of our results for the topological susceptibility agrees nicely at small quark mass with the predictions of lowest-order SU(3) chiral perturbation theory, thus lending support to the validity of the fourth-root procedure.

Van de Water, R.; Bernard, C.; Laiho, J.; Billeter, B.; DeTar, C.; Levkova, L.; Oktay, M.B.; Gottlieb, S.; Heller, U.M.; Hetrick, J.E.; Osborn, J.; Sugar, R.L.; (MILC Collaboration)

2010-06-15

182

Supersymmetric Black Holes with Lens-Space Topology

NASA Astrophysics Data System (ADS)

We present a new supersymmetric, asymptotically flat, black hole solution to five-dimensional supergravity. It is regular on and outside an event horizon of lens-space topology L (2 ,1 ) . It is the first example of an asymptotically flat black hole with lens-space topology. The solution is characterized by a charge, two angular momenta, and a magnetic flux through a noncontractible disk region ending on the horizon, with one constraint relating these.

Kunduri, Hari K.; Lucietti, James

2014-11-01

183

Supersymmetric black holes with lens-space topology.

We present a new supersymmetric, asymptotically flat, black hole solution to five-dimensional supergravity. It is regular on and outside an event horizon of lens-space topology L(2,1). It is the first example of an asymptotically flat black hole with lens-space topology. The solution is characterized by a charge, two angular momenta, and a magnetic flux through a noncontractible disk region ending on the horizon, with one constraint relating these. PMID:25479484

Kunduri, Hari K; Lucietti, James

2014-11-21

184

Topological aspect of black hole with Skyrme hair

Based on the $\\phi$-mapping topological current theory, we show that the presence of the black hole leaves fractional baryon charge outside the horizon in the Einstein-Skyrme theory. A topological current is derived from the Einstein-Skyrme system, which corresponds to the monopoles around the black hole. The branch process (splitting, merging and intersection) is simply discussed during the evolution of the monopoles.

Yi-Shi Duan; Xin-Hui Zhang; Li Zhao

2007-03-19

185

Topological insulator quantum dot with tunable barriers.

Thin (6-7 quintuple layer) topological insulator Bi(2)Se(3) quantum dot devices are demonstrated using ultrathin (2-4 quintuple layer) Bi(2)Se(3) regions to realize semiconducting barriers which may be tuned from ohmic to tunneling conduction via gate voltage. Transport spectroscopy shows Coulomb blockade with large charging energy >5 meV and additional features implying excited states. PMID:22181853

Cho, Sungjae; Kim, Dohun; Syers, Paul; Butch, Nicholas P; Paglione, Johnpierre; Fuhrer, Michael S

2012-01-11

186

Black hole attractors and the topological string

A simple relationship of the form ZBH=|Ztop|2 is conjectured, where ZBH is a supersymmetric partition function for a four-dimensional BPS black hole in a Calabi-Yau compactification of Type II superstring theory and Ztop is a second-quantized topological string partition function evaluated at the attractor point in moduli space associated to the black hole charges. Evidence for the conjecture in a

Hirosi Ooguri; Andrew Strominger; Cumrun Vafa

2004-01-01

187

Topological quantum distillation.

We construct a class of topological quantum codes to perform quantum entanglement distillation. These codes implement the whole Clifford group of unitary operations in a fully topological manner and without selective addressing of qubits. This allows us to extend their application also to quantum teleportation, dense coding, and computation with magic states. PMID:17155532

Bombin, H; Martin-Delgado, M A

2006-11-01

188

Topological Insulators & Superconductors

Topological Insulators & Superconductors New Frontiers in Low-Dimensional Systems Program 3-5 November 2010 Jadwin Hall, Fourth Floor, Room 407 Topological Insulators and Superconductors have quickly insulators but have holographic edge or surface states which are robust to disorder and impurities

189

On Effective Topological Spaces

Starting with D. Scott's work on the mathematical foundations of programming language semantics, interest in topology has grown up in theoretical computer science, under the slogan `open sets are semidecidable properties'. But whereas on effectively given Scott domains all such properties are also open, this is no longer true in general. In this paper a characterization of effectively given topological

Dieter Spreen

1998-01-01

190

DNA Topology: Fundamentals Sergei M Mirkin, University of Illinois at Chicago, Illinois, USA Topological characteristics of DNA and specifically DNA supercoiling influence all major DNA transactions in living cells. DNA supercoiling induces the formation of unusual secondary structure by specific DNA

Mirkin, Sergei

191

Superpositional Quantum Network Topologies

We introduce superposition-based quantum networks composed of (i) the classical perceptron model of multilayered, feedforward neural networks and (ii) the algebraic model of evolving reticular quantum structures as described in quantum gravity. The main feature of this model is moving from particular neural topologies to a quantum metastructure which embodies many differing topological patterns. Using quantum parallelism, training is possible

Christopher Altman; Jaroslaw Pykacz; Romàn R. Zapatrin

2004-01-01

192

Areview of the notion, properties and the use of topological defects in 2d conformal field theories is presented. An emphasis is made on the recent interpretation of such operators in non-rational theories, as describing Wilson-'t Hooft loop operators of N = 2 supersymmetric 4d topological theories.

Petkova, V. B., E-mail: petkova@inrne.bas.bg [Bulgarian Academy of Sciences, Institute of Nuclear Research and Nuclear Energy (Bulgaria)

2013-10-15

193

Topologically Adaptable Snakes

This paper presents a topologically adaptable snakes model for image segmentation and object representation. The model is embedded in the framework of domain subdi- vision using simplicial decomposition. This framework ex- tends the geometric and topological adaptability of snakes while retaining all of the features of traditional snakes, s uch as user interaction, and overcoming many of the limitations of

Tim Mcinerney; Demetri Terzopoulos

1995-01-01

194

Code of Federal Regulations, 2010 CFR

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2010-01-01

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2011-01-01

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2011-04-01

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2012-04-01

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2011-04-01

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2012-04-01

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2013-04-01

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...PARTY PAYERS OF REASONABLE CHARGES FOR HEALTHCARE SERVICES § 220.14 Definitions...beneficiaries. Covered beneficiaries are all healthcare beneficiaries under chapter 55 of...Facilities” or “USTFs”). Healthcare services. Healthcare services...

2011-07-01

206

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2013-07-01

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2012-07-01

208

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...Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEASING OF OSAGE RESERVATION LANDS, OKLAHOMA, FOR MINING, EXCEPT OIL AND GAS § 214.1 Definition. The term “officer in charge” shall refer to the...

2011-04-01

209

Geometrically induced electric polarization in conical topological insulators

We study the topological magnetoelectric effect on a conical topological insulator when a point charge $q$ is near the cone apex. The Hall current induced on the cone surface and the image charge configuration are determined. We also study a kind of gravitational Aharonov-Bohm effect in this geometry and realize a phase diference betwen the components of the wavefunctions (spinors) upon closed parallel transport around the (singular) cone tip. Concretely, a net current flowing towards cone apex (or botton) shows up, yielding electric polarization of the conical topological insulator. Such an effect may be detected, for instance, by means of the net accumulated Hall charge near the apex. Once it depends only on the geometry of the material (essetially, the cone apperture angle) this may be faced as a microscopic scale realization of (2+1)-dimensional Einstein gravity.

Jakson M. Fonseca; Winder A. Moura-Melo; Afranio R. Pereira

2011-11-29

210

The Scott Topology Induces the Weak Topology

Given a probability measure on a compact metric space, we construct an increasing chain of valuations on the upper space of the metric space whose least upper bound is the measure. We then obtain the expected value of any Holder continuous function with respect to the measure up to any precision. We prove that the Scott topology induces the weak

Abbas Edalat

1996-01-01

211

NSDL National Science Digital Library

The electric field lines from a point charge evolve in time as the charge moves. Watch radiation propagate outward at the speed of light as you wiggle the charge. Stop a moving charge to see bremsstrahlung (braking) radiation. Explore the radiation patterns as the charge moves with sinusoidal, circular, or linear motion. You can move the charge any way you like, as long as you donât exceed the speed of light.

Simulations, Phet I.; Dubson, Michael; Paul, Ariel

2013-02-01

212

Topological Structure of the Many Vortices Solution in Jackiw-Pi Model

NASA Astrophysics Data System (ADS)

By using the gauge potential decomposition, we discuss the self-dual equation and its solution in Jackiw-Pi model. We obtain a new concrete self-dual equation and find relationship between Chern-Simons vortices solution and topological number which is determined by Hopf indices and Brouwer degrees of ?-mapping. To show the meaning of topological number we give several figures with different topological numbers. In order to investigate the topological properties of many vortices, we use five parameters (two positions, one scale, one phase per vortex and one charge of each vortex) to describe each vortex in many vortices solutions in Jackiw-Pi model. For many vortices, we give three figures with different topological numbers to show the effect of the charge on the many vortices solutions. We also study the quantization of flux of those vortices related to the topological numbers in this case.

Lee, Xi-Guo; Liu, Zi-Yu; Li, Yong-Qing; Zhang, Peng-Ming

213

Static topologically-nontrivial configurations in sigma-models, for spatial\\u000adimension D \\\\geq 2, are unstable. The question addressed here is whether such\\u000asigma-model solitons can be stabilized by steady rotation in internal space;\\u000athat is, rotation in a global SO(2) symmetry. This is the mechanism which\\u000astabilizes Q-balls (non-topological solitons). The conclusion is that the\\u000aQ-mechanism can stabilize topological solitons in D=2

R. S. Ward

2003-01-01

214

Topological Landscapes: A Terrain Metaphor

Topological Landscapes: A Terrain Metaphor for Scientific Data Gunther H. Weber1 Peer-Timo Bremer2 more (refer to paper) #12;Presentation of Topological Information Â· Topological analysis powerful tool Â Inherent data complexity Â Noise Â· Need to consider topology at various scales Hierarchical contour tree

Geddes, Cameron Guy Robinson

215

Polydispersity-driven topological defects as order-restoring excitations

The engineering of defects in crystalline matter has been extensively exploited to modify the mechanical and electrical properties of many materials. Recent experiments on manipulating extended defects in graphene, for example, show that defects direct the flow of electric charges. The fascinating possibilities offered by defects in two dimensions, known as topological defects, to control material properties provide great motivation to perform fundamental investigations to uncover their role in various systems. Previous studies mostly focus on topological defects in 2D crystals on curved surfaces. On flat geometries, topological defects can be introduced via density inhomogeneities. We investigate here topological defects due to size polydispersity on flat surfaces. Size polydispersity is usually an inevitable feature of a large variety of systems. In this work, simulations show well-organized induced topological defects around an impurity particle of a wrong size. These patterns are not found in systems of identical particles. Our work demonstrates that in polydispersed systems topological defects play the role of restoring order. The simulations show a perfect hexagonal lattice beyond a small defective region around the impurity particle. Elasticity theory has demonstrated an analogy between the elementary topological defects named disclinations to electric charges by associating a charge to a disclination, whose sign depends on the number of its nearest neighbors. Size polydispersity is shown numerically here to be an essential ingredient to understand short-range attractions between like-charge disclinations. Our study suggests that size polydispersity has a promising potential to engineer defects in various systems including nanoparticles and colloidal crystals. PMID:24706918

Yao, Zhenwei; Olvera de la Cruz, Monica

2014-01-01

216

48 CFR 552.232-77 - Payment By Government Charge Card.

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2011-10-01

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48 CFR 552.232-77 - Payment By Government Charge Card.

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2010-10-01

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2012-10-01

219

48 CFR 552.232-77 - Payment By Government Charge Card.

Code of Federal Regulations, 2013 CFR

2013-10-01

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221

42 CFR 405.509 - Determining the inflation-indexed charge.

Code of Federal Regulations, 2012 CFR

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42 CFR 405.509 - Determining the inflation-indexed charge.

Code of Federal Regulations, 2011 CFR

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2011-10-01

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42 CFR 405.509 - Determining the inflation-indexed charge.

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2013-10-01

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42 CFR 405.509 - Determining the inflation-indexed charge.

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2010-10-01

225

The nonmodular topological phase and phase singularities

NASA Astrophysics Data System (ADS)

Generalizing an earlier definition of the noncyclic geometric phase [R. Bhandari, Phys. Lett. A 157 (1991) 221], a nonmodular topological phase is defined with reference to a generic time-dependent two-slit interference experiment involving particles with N internal states in which the internal state of both the beams undergoes unitary evolution. A simple proof of the shorter geodesic rule for closure of the open path is presented and several useful new insights into the behavior of the dynamical and geometrical components of the phase shift presented. An effective Hamiltonian interpretation of the observable phase shifts is also presented.

Bhandari, Rajendra

2011-09-01

226

We describe a new Hybrid Monte Carlo (HMC) algorithm for dynamical overlap fermions, which improves the rate of topological index changes by adding an additional (intensive) term to the action for the molecular dynamics part of the algorithm. The metropolis step still uses the exact action, so that the Monte Carlo algorithm still generates the correct ensemble. By tuning this new term, we hope to be able to balance the acceptance rate of the HMC algorithm and the rate of topological index changes. We also describe how suppressing, but not eliminating, the small eigenvalues of the kernel operator may improve the volume scaling of the cost per trajectory for overlap HMC while still allowing topological index changes. We test this operator on small lattices, comparing our new algorithm with an old overlap HMC algorithm with a slower rate of topological charge changes, and an overlap HMC algorithm which fixes the topology. Our new HMC algorithm more than doubles the rate of topological index changes compared to the previous state of the art, while maintaining the same metropolis acceptance rate. We investigate the effect of topological index changes on the local topological charge density, measured using an improved field theoretic operator after heavy smearing. We find that the creation and annihilation of large lumps of topological charge is increased with the new algorithm.

Nigel Cundy; Weonjong Lee

2011-10-10

227

Wild topology, hyperbolic geometry and fusion algebra of high energy particle physics

The relation between Wild Topology, Hyperbolic Geometry and Fusion Algebra on the one side and the charge and coupling constants of the standard model and quantum gravity on the other is examined.The close connection found between E(?) theory and the Topological theory of four manifolds as well as the theory of fundamental groups is elucidated using various classical theories and

M. S. El Naschie

2002-01-01

228

We discuss physical properties of “integer” topological phases of bosons in D = 3 + 1 dimensions, protected by internal symmetries like time reversal and/or charge conservation. These phases invoke interactions in a ...

Vishwanath, Ashvin

229

We investigate topological properties of density matrices motivated by the question to what extent phenomena like topological insulators and superconductors can be generalized to mixed states in the framework of open quantum systems. The notion of geometric phases has been generalized from pure to mixed states by Uhlmann in [Rep. Math. Phys. 24, 229 (1986)], where an emergent gauge theory over the density matrices based on their pure-state representation in a larger Hilbert space has been reported. However, since the uniquely defined square root $\\sqrt{\\rho}$ of a density matrix $\\rho$ provides a global gauge, this construction is always topologically trivial. Here, we study a more restrictive gauge structure which can be topologically non-trivial and is capable of resolving homotopically distinct mappings of density matrices subject to various spectral constraints. Remarkably, in this framework, topological invariants can be directly defined and calculated for mixed states. In the limit of pure states, the well known system of topological invariants for gapped band structures at zero temperature is reproduced. We compare our construction with recent approaches to Chern insulators at finite temperature.

Jan Carl Budich; Sebastian Diehl

2015-01-16

230

Seeing the magnetic monopole through the mirror of topological surface states

Existence of the magnetic monopole is compatible with the fundamental laws of nature, however, this illusive particle has yet to be detected experimentally. In this work, we show that an electric charge near the topological surface state induces an image magnetic monopole charge due to the topological magneto-electric effect. The magnetic field generated by the image magnetic monopole can be experimentally measured, and the inverse square law of the field dependence can be determined quantitatively. We propose that this effect can be used to experimentally realize a gas of quantum particles carrying fractional statistics, consisting of the bound states of the electric charge and the image magnetic monopole charge.

Qi, Xiao-Liang; Li, Rundong; /Stanford U., Phys. Dept.; Zang, Jiadong; /Fudan U.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept. /Fudan U.

2010-03-25

231

The electric charge and magnetic moment of neutral fundamental particles

The article focuses on the issue of the two definitions of charge, mainly the gauge charge and the effective charge of fundamental particles. Most textbooks on classical electromagnetism and quantum field theory only works with the gauge charges while the concept of the induced charge remains unattended. In this article it has been shown that for intrinsically charged particles both of the charges remain the same but there can be situations where an electrically neutral particle picks up some electrical charge from its plasma surrounding. The physical origin and the scope of application of the induced charge concept has been briefly discussed in the article.

Kaushik Bhattacharya

2009-05-27

232

Topological Insulators and Superconductors from D-branes

Realization of topological insulators (TIs) and superconductors (TSCs), such as the quantum spin Hall effect and the Z_2 topological insulator, in terms of D-branes in string theory is proposed. We establish a one-to-one correspondence between the K-theory classification of TIs/TSCs and D-brane charges. The string theory realization of TIs and TSCs comes naturally with gauge interactions, and the Wess-Zumino term of the D-branes gives rise to a gauge field theory of topological nature. This sheds light on TIs and TSCs beyond non-interacting systems, and the underlying topological field theory description thereof. In particular, our string theory realization includes the honeycomb lattice Kitaev model in two spatial dimensions, and its higher-dimensional extensions.

Shinsei Ryu; Tadashi Takayanagi

2010-08-08

233

TOPPER: Topology Prediction of Transmembrane Protein Based on Evidential Reasoning

The topology prediction of transmembrane protein is a hot research field in bioinformatics and molecular biology. It is a typical pattern recognition problem. Various prediction algorithms are developed to predict the transmembrane protein topology since the experimental techniques have been restricted by many stringent conditions. Usually, these individual prediction algorithms depend on various principles such as the hydrophobicity or charges of residues. In this paper, an evidential topology prediction method for transmembrane protein is proposed based on evidential reasoning, which is called TOPPER (topology prediction of transmembrane protein based on evidential reasoning). In the proposed method, the prediction results of multiple individual prediction algorithms can be transformed into BPAs (basic probability assignments) according to the confusion matrix. Then, the final prediction result can be obtained by the combination of each individual prediction base on Dempster's rule of combination. The experimental results show that the proposed method is superior to the individual prediction algorithms, which illustrates the effectiveness of the proposed method. PMID:23401665

Deng, Xinyang; Liu, Qi; Hu, Yong; Deng, Yong

2013-01-01

234

Coherent single-spin source based on topological insulators

NASA Astrophysics Data System (ADS)

We report on the injection of quantized pure spin current into quantum conductors. In particular, we propose an on-demand single-spin source generated by periodically varying the gate voltages of two quantum dots that are connected to a two-dimensional topological insulator via tunneling barriers. Due to the nature of the helical states of the topological insulator, one or several spin pairs can be pumped out per cycle giving rise to a pure quantized alternating spin current. Depending on the phase difference between two gate voltages, this device can serve as an on-demand single-spin emitter or single-charge emitter. Again, due to the helicity of the topological insulator, the single-spin emitter or charge emitter is dissipationless and immune to disorder. The proposed single-spin emitter can be an important building block of future spintronic devices.

Xing, Yanxia; Yang, Zhong-liu; Sun, Qing-feng; Wang, Jian

2014-08-01

235

Aharonov-Bohm interference in topological insulator nanoribbons.

Topological insulators represent unusual phases of quantum matter with an insulating bulk gap and gapless edges or surface states. The two-dimensional topological insulator phase was predicted in HgTe quantum wells and confirmed by transport measurements. Recently, Bi(2)Se(3) and related materials have been proposed as three-dimensional topological insulators with a single Dirac cone on the surface, protected by time-reversal symmetry. The topological surface states have been observed by angle-resolved photoemission spectroscopy experiments. However, few transport measurements in this context have been reported, presumably owing to the predominance of bulk carriers from crystal defects or thermal excitations. Here we show unambiguous transport evidence of topological surface states through periodic quantum interference effects in layered single-crystalline Bi(2)Se(3) nanoribbons, which have larger surface-to-volume ratios than bulk materials and can therefore manifest surface effects. Pronounced Aharonov-Bohm oscillations in the magnetoresistance clearly demonstrate the coherent propagation of two-dimensional electrons around the perimeter of the nanoribbon surface, as expected from the topological nature of the surface states. The dominance of the primary h/e oscillation, where h is Planck's constant and e is the electron charge, and its temperature dependence demonstrate the robustness of these states. Our results suggest that topological insulator nanoribbons afford promising materials for future spintronic devices at room temperature. PMID:20010826

Peng, Hailin; Lai, Keji; Kong, Desheng; Meister, Stefan; Chen, Yulin; Qi, Xiao-Liang; Zhang, Shou-Cheng; Shen, Zhi-Xun; Cui, Yi

2010-03-01

236

Topological Insulators Avoid the Parity Anomaly

The surface of a 3+1d topological insulator hosts an odd number of gapless Dirac fermions when charge conjugation and time-reversal symmetries are preserved. Viewed as a purely 2+1d system, this surface theory would necessarily explicitly break parity and time-reversal when coupled to a fluctuating gauge field. Here we explain why such a state can exist on the boundary of a 3+1d system without breaking these symmetries, even if the number of boundary components is odd. This is accomplished from two complementary perspectives: topological quantization conditions and regularization. We first discuss the conditions under which (continuous) large gauge transformations may exist when the theory lives on a boundary of a higher-dimensional spacetime. Next, we show how the higher-dimensional bulk theory is essential in providing a parity-invariant regularization of the theory living on the lower-dimensional boundary or defect.

Michael Mulligan; F. J. Burnell

2013-01-17

237

Black hole mass and angular momentum in topologically massive gravity

We extend the Abbott Deser Tekin approach to the computation of the Killing charge for a solution of topologically massive gravity (TMG) linearized around an arbitrary background. This is then applied to evaluate the mass and angular momentum of black hole solutions of TMG with non-constant curvature asymptotics. The resulting values, together with the appropriate black hole entropy, fit nicely

Adel Bouchareb; Gérard Clément

2007-01-01

238

Pair Production of Topological anti de Sitter Black Holes

The pair creation of black holes with event horizons of non-trivial topology is described. The spacetimes are all limiting cases of the cosmological $C$ metric. They are generalizations of the $(2+1)$ dimensional black hole and have asymptotically anti de Sitter behaviour. Domain walls instantons can mediate their pair creation for a wide range of mass and charge.

R. B. Mann

1996-07-28

239

PROJECT REPORT Energy Management for EV Charge Station in Distributed Power System

and EV instead of traditional cars. Usually, Charging process for EV would be done in a charge station of the total amount of the generated electricity could not satisfy the need of the EV charge station. Typically power source so as to prolong battery life and Fig 1 Charging Station Topology #12;minimize the energy

He, Lei

240

A study of charging control of lead-acid battery for electric vehicles

The object of this paper is to investigate the circuit topologies and control techniques for fast charging of battery for the electric vehicle (EV). Analysis and comparison of fast charging characteristics for different charging controls are presented. A charging and discharging monitoring system was implemented based on a DSP. To improve the utilization of EV, it is necessary to design

Chih-Chiang Hua; Meng-Yu Lin

2000-01-01

241

Image Segmentation by Non-topological Erosion and Topological Expansion

A new segmentation method is suggested to distinguish the foreground from the background in gray-level images. The method\\u000a is based on a 2-step process, respectively employing non-topological pixel removal (non-topological erosion) and topological\\u000a region growing (topological expansion). The first step is aimed at identifying suitable seeds, corresponding to the objects\\u000a of interest in the image, while the second step associates

Giuliana Ramella; Gabriella Sanniti Di Baja

2007-01-01

242

Topology optimized microbioreactors.

This article presents the fusion of two hitherto unrelated fields--microbioreactors and topology optimization. The basis for this study is a rectangular microbioreactor with homogeneously distributed immobilized brewers yeast cells (Saccharomyces cerevisiae) that produce a recombinant protein. Topology optimization is then used to change the spatial distribution of cells in the reactor in order to optimize for maximal product flow out of the reactor. This distribution accounts for potentially negative effects of, for example, by-product inhibition. We show that the theoretical improvement in productivity is at least fivefold compared with the homogeneous reactor. The improvements obtained by applying topology optimization are largest where either nutrition is scarce or inhibition effects are pronounced. PMID:21404253

Schäpper, Daniel; Lencastre Fernandes, Rita; Lantz, Anna Eliasson; Okkels, Fridolin; Bruus, Henrik; Gernaey, Krist V

2011-04-01

243

NSDL National Science Digital Library

Students come to understand static electricity by learning about the nature of electric charge, and different methods for charging objects. In a hands-on activity, students induce an electrical charge on various objects, and experiment with electrical repulsion and attraction.

Integrated Teaching And Learning Program

244

Topological DeNoising: Strengthening the Topological Signal

Topological methods, including persistent homology, are powerful tools for analysis of high-dimensional data sets but these methods rely almost exclusively on thresholding techniques. In noisy data sets, thresholding does not always allow for the recovery of topological information. We present an easy to implement, computationally efficient pre-processing algorithm to prepare noisy point cloud data sets for topological data analysis. The

Jennifer Kloke; Gunnar Carlsson

2009-01-01

245

Topological Defects in Cosmology

Topological defects are ubiquitous in condensed-matter physics but only hypothetical in the early universe. In spite of this, even an indirect evidence for one of these cosmic objects would revolutionize our vision of the cosmos. We give here an introduction to the subject of cosmic topological defects and their possible observable signatures. Beginning with a review of the basics of general defect formation and evolution, we then focus on mainly two topics in some detail: conducting strings and vorton formation, and some specific imprints in the cosmic microwave background radiation from simulated cosmic strings.

Alejandro Gangui

2001-10-11

246

We consider extended Hubbard models with repulsive interactions on a honeycomb lattice, and the transitions from the semimetal to Mott insulating phases at half-filling. Because of the frustrated nature of the second-neighbor interactions, topological Mott phases displaying the quantum Hall and the quantum spin Hall effects are found for spinless and spin fermion models, respectively. The mean-field phase diagram is presented and the fluctuations are treated within the random phase approximation. Renormalization group analysis shows that these states can be favored over the topologically trivial Mott insulating states.

Raghu, S.

2010-03-02

247

Butterflies and topological quantum numbers

The Hofstadter model illustrates the notion of topological quantum numbers and how they account for the quantization of the Hall conductance. It gives rise to colorful fractal diagrams of butterflies where the colors represent the topological quantum numbers.

J. E. Avron; D. Osadchy

2001-10-20

248

Butterflies and topological quantum numbers

The Hofstadter model illustrates the notion of topological quantum numbers and how they account for the quantization of the Hall conductance. It gives rise to colorful fractal diagrams of butterflies where the colors represent the topological quantum numbers.

J. E. Avron; D. Osadchy

2001-01-01

249

Holographic RG flows from Quasi-Topological Gravity

NASA Astrophysics Data System (ADS)

We investigate the holographic Renormalization Group (RG) flows and the critical phenomena that take place in the QFT's dual to the d-dimensional cubic Quasi-Topological Gravity coupled to scalar matter. The knowledge of the corresponding flat Domain Walls (DW's) solutions allows us to derive the explicit form of the QFT's ?-functions, as well as of the trace anomalies a(l) and c(l), in terms of the matter superpotential. As a consequence we are able to determine the complete set of CFT data characterizing the universality classes of the UV and IR critical points and to follow the particular RG evolution of this data. We further analyse the dependence of the critical properties of such dual QFT's on the values of the Lovelock couplings and on the shape of the superpotential. For odd values of d, the explicit form of the "a and c-central charges" as functions of the running coupling constant, enable us to establish the conditions under which the a&c-Theorems for their decreasing are valid. The restrictions imposed on the massless holographic RG flows by the requirements of the positivity of the energy fluxes are derived. The particular case of quartic Higgs-like superpotential is studied in detail. It provides an example of unitary dual QFT's having few c?a-critical points representing second or infinite order phase transitions. Depending on the range of the values of the coupling constant they exhibit massive and massless phases, described by a chain of distinct DW's solutions sharing common boundaries. Remember that the definition of the new maximal "h-scale" in the case of negative h<0 is given by fh=L2/(.

Camara da Silva, U.; Sotkov, G. M.

2013-09-01

250

1 Â· Definition Â· Chemistry Â· Factors Â· Mitigation MinE 422 Acid Rock Drainage Online `Gard Guide is a great source of information Terminology Â· acid rock drainage (ARD) Â· saline drainage (SD) Â· acid mine or acid and metalliferous drainage (AMD) Â· mining influenced water (MIW) Â· neutral mine drainage (NMD

Boisvert, Jeff

251

Topological Correction of Subcortical Segmentation

approaches have tried to directly incorporate topological constraints into the segmentation process [1 is that local topological constraints can lead to strong geometrical errors, and that the final segmentation canTopological Correction of Subcortical Segmentation Florent SÂ´egonne1,2 , Eric Grimson1 , and Bruce

Fischl, Bruce

252

Topological groundwater hydrodynamics Garrison Sposito

Topological groundwater hydrodynamics Garrison Sposito Department of Civil and Environmental; received in revised form 10 November 2000; accepted 15 November 2000 Abstract Topological groundwater, the topological characteristics of groundwater Â¯ows governed by the Darcy law are studied. It is demonstrated that

Chen, Yiling

253

Multimaterial topology optimization

Apr 15, 2013 ... The variational multilevel sets approach (cf. [14, 15]) has been ... framework to convert almost every binary phase topology optimization solver to its multiphase .... min ?h?Ah. J h(?h,Uh(?h)) subject to : Rh(M(?h),Uh(?h)) = 0 in ?h ...... beam, bridge structure and MBB beam; as shown in figure 1. The load F ...

R. Tavakoli

2013-04-15

254

Holographic fractional topological insulators

We give a holographic realization of the recently proposed low-energy effective action describing a fractional topological insulator. In particular we verify that the surface of this hypothetical material supports a fractional quantum Hall current corresponding to half that of a Laughlin state.

Hoyos, Carlos; Jensen, Kristan; Karch, Andreas [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

2010-10-15

255

Homotopy Theory of Strong and Weak Topological Insulators

We use homotopy theory to extend the notion of strong and weak topological insulators to the non-stable regime (low numbers of occupied/empty energy bands). We show that for strong topological insulators in d spatial dimensions to be "truly d-dimensional", i.e. not realizable by stacking lower-dimensional insulators, a more restrictive definition of "strong" is required. However, this does not exclude weak topological insulators from being "truly d-dimensional", which we demonstrate by an example. Additionally, we prove some useful technical results, including the homotopy theoretic derivation of the factorization of invariants over the torus into invariants over spheres in the stable regime, as well as the rigorous justification of replacing $T^d$ by $S^d$ and $T^{d_k}\\times S^{d_x}$ by $S^{d_k+d_x}$ as is common in the current literature.

Ricardo Kennedy; Charles Guggenheim

2014-09-08

256

The purpose of this article is to review the theory of charge imbalance, and to discuss its relevance to a number of experimental situations. We introduce the concepts of quasiparticle charge and charge imbalance, and discuss the generation and detection of charge imbalance by tunneling. We describe the relaxation of the injected charge imbalance by inelastic scattering processes, and show how the Boltzmann equation can be solved to obtain the steady state quasiparticle distribution and the charge relaxation rate. Details are given of experiments to measure charge imbalance and the charge relaxation rate when inelastic scattering is the predominant relaxation mechanism. Experiments on and theories of other charge relaxation mechanisms are discussed, namely relaxation via elastic scattering in the presence of energy gap anisotropy, or in the presence of a pair breaking mechanism such as magnetic impurities or an applied supercurrent or magnetic field. We describe three other situations in which charge imbalance occurs, namely the resistance of the NS interface, phase slip centers, and the flow of a supercurrent in the presence of a temperature gradient.

Clarke, John

1980-09-01

257

Typing rule-based transformations over topological collections

Pattern-matching programming is an example of a rule-based programming style developed in functional languages. This programming style is intensively used in dialects of ML but is restricted to algebraic data-types. This restriction limits the field of application. However, as shown by (9) at RULE'02, case-based function definitions can be extended to more general data structures called topological collections. We show

Julien Cohen

2003-01-01

258

Typing rule-based transformations over topological collections

Pattern-matching programming is an example of a rule-based programming style developed in functional languages. This programming style is intensively used in dialects of ML but is restricted to algebraic data-types. This restriction limits the field of application. However, as shown by Giavitto and Michel at RULE'02, case-based function definitions can be extended to more general data structures called topological collections.

Julien Cohen

2009-01-01

259

Topology Optimized Synthesis of Planar Kinematic Rigid Body Mechanisms

Regarding the essential engineering design tasks in the systematic development process of rigid body mechanisms, three major\\u000a stages can be distinguished (Erdman, 1995; Olson, 1985; Sandor, Erdman, 1984). The first step deals with the problem definition with respect to the functional and topological requirements. The desired\\u000a functionality and kinematic behavior as well as the complexity of the mechanism, the degree

Peter Eberhard; Timo Gaugele; Kai Sedlaczek

260

Conserved charges in 3D gravity

The covariant canonical expression for the conserved charges, proposed by Nester, is tested on several solutions in three-dimensional gravity with or without torsion and topologically massive gravity. In each of these cases, the calculated values of energy momentum and angular momentum are found to satisfy the first law of black hole thermodynamics.

Blagojevic, M.; Cvetkovic, B. [University of Belgrade, Institute of Physics, P. O. Box 57, 11001 Belgrade (Serbia)

2010-06-15

261

We consider Bose-Einstein condensation of massive electrically charged scalars in a uniform background of charged fermions. We focus on the case when the scalar condensate screens the background charge, while the net charge of the system resides on its boundary surface. A distinctive signature of this substance is that the photon acquires a Lorentz-violating mass in the bulk of the condensate. Due to this mass, the transverse and longitudinal gauge modes propagate with different group velocities. We give qualitative arguments that at high enough densities and low temperatures a charged system of electrons and helium-4 nuclei, if held together by laboratory devices or by force of gravity, can form such a substance. We briefly discuss possible manifestations of the charged condensate in compact astrophysical objects.

Gregory Gabadadze; Rachel A. Rosen

2007-06-15

262

The Topological Effects of Smoothing.

Scientific data sets generated by numerical simulations or experimental measurements often contain a substantial amount of noise. Smoothing the data removes noise but can have potentially drastic effects on the qualitative nature of the data, thereby influencing its characterization and visualization via topological analysis, for example. We propose a method to track topological changes throughout the smoothing process. As a pre-processing step, we over-smooth the data and collect a list of topological events, specifically the creation and destruction of extremal points. During rendering, it is possible to select the number of topological events by interactively manipulating a merging parameter. The result that a specific amount of smoothing has on the topology of the data is illustrated using a topology-derived transfer function that relates region connectivity of the smoothed data to the original regions of the unsmoothed data. This approach enables visual as well as quantitative analysis of the topological effects of smoothing. PMID:21519107

Shafii, Sohail; Dillard, Scott E; Hlawitschka, Mario; Hamann, Bernd

2011-04-12

263

Topological aspects of fermions on hyperdiamond

Motivated by recent results on the index of the Dirac operator D={gamma}{sup {mu}}D{sub {mu}} of QCD on lattice and also by results on topological features of electrons and holes of two-dimensional graphene, we compute in this paper the index of D for fermions living on a family of even-dimensional lattices denoted as L{sub 2N} and describing the 2N-dimensional generalization of the graphene honeycomb. The calculation of this topological index is done by using the direct method based on solving explicitly the gauged Dirac equation and also by using specific properties of the lattices L{sub 2N}, which are shown to be intimately linked with the weight lattices of SU(2N+ 1). The index associated with the two leading N= 1 and N= 2 elements of this family describe precisely the chiral anomalies of graphene and QCD{sub 4}. Comments on the method using the spectral flow approach as well as the computation of the topological charges on 2-cycles of 2N-dimensional compact supercell in L{sub 2N} and applications to QCD{sub 4} are also given.

Saidi, E. H. [Hassan II Academy of Science and Technology, Avenue Mohammed VI, KM 4, Souissi, Rabat (Morocco); Lab Of High Energy Physics, Modeling and Simulations, Faculty of Science, University Mohammed V-Agdal, Rabat (Morocco); Fassi-Fehri, O.; Bousmina, M. [Hassan II Academy of Science and Technology, Avenue Mohammed VI, KM 4, Souissi, Rabat (Morocco)

2012-07-15

264

Topological magnetization jumps in a confined chiral soliton lattice

NASA Astrophysics Data System (ADS)

We demonstrate that a finite-size chiral soliton lattice formed in a chiral helimagnet with fixed boundary conditions exhibits magnetization jumps in a response to the magnetic field applied perpendicular to the chiral axis. The imposed boundary conditions lead to confinement of topological charges and quantized spatial periods of the soliton lattice. Building an envelope of the ground-state energies belonging to different topological sectors, we find the magnetization jumps related with the level crossing. After numerically establishing the quantization condition, we also develop a field-theoretical model to support the numerical results.

Kishine, Jun-ichiro; Bostrem, I. G.; Ovchinnikov, A. S.; Sinitsyn, Vl. E.

2014-01-01

265

Topological Nature of Optical Bound States in the Continuum

NASA Astrophysics Data System (ADS)

Optical bound states in the continuum (BICs) have recently been realized in photonic crystal slabs, where the disappearance of out-of-plane radiation turns leaky resonances into guided modes with infinite lifetimes. We show that such BICs are vortex centers in the polarization directions of far-field radiation. They carry conserved and quantized topological charges, defined by the winding number of the polarization vectors, which ensure their robust existence and govern their generation, evolution, and annihilation. Our findings connect robust BICs in photonics to a wide range of topological physical phenomena.

Zhen, Bo; Hsu, Chia Wei; Lu, Ling; Stone, A. Douglas; Solja?i?, Marin

2014-12-01

266

Optically engineering the topological properties of a spin Hall insulator.

Time-periodic perturbations can be used to engineer topological properties of matter by altering the Floquet band structure. This is demonstrated for the helical edge state of a spin Hall insulator in the presence of monochromatic circularly polarized light. The inherent spin structure of the edge state is influenced by the Zeeman coupling and not by the orbital effect. The photocurrent (and the magnetization along the edge) develops a finite, helicity-dependent expectation value and turns from dissipationless to dissipative with increasing radiation frequency, signalling a change in the topological properties. The connection with Thouless' charge pumping and nonequilibrium zitterbewegung is discussed, together with possible experiments. PMID:22400947

Dóra, Balázs; Cayssol, Jérôme; Simon, Ferenc; Moessner, Roderich

2012-02-01

267

Robust extended states in a topological bulk model with even spin-Chern invariant

This paper demonstrates the existence of topological models with gapped edge states but protected extended bulk states against disorder. Such systems will be labeled as trivial by the current classification of topological insulators. Our finding calls for a re-examination of the definition of a topological insulator. The analysis is supported by extensive numerical data for a model of non-interacting electrons in the presence of strong disorder. In the clean limit, the model displays a topological insulating phase with spin-Chern number $C_s$=2 and gapped edge states. In the presence of disorder, level statistics on energy spectrum reveals regions of extended states displaying levitation and pair annihilation. Therefore, the extended states carry a topological invariant robust against disorder. By driving the Fermi level over the mobility edges, it is shown that this invariant is precisely the spin-Chern number. The protection mechanism for the extended state is explained.

Hadassah Shulman; Emil Prodan

2010-11-24

268

Friedel sum rule in the presence of topological defects for graphene

The Friedel sum rule is extended to deal with topological defects for the case of a graphene cone in the presence of an external Coulomb charge. The dependence in the way the number of states change due to both the topological defect as well as the Coulomb charge are studied. Our analysis addresses both the cases of a subcritical as well as a supercritical value of the Coulomb charge. We also discuss the experimental implications of introducing a self-adjoint extension of the system Hamiltonian. We argue that the boundary conditions following from the self-adjoint extension encode the effect of short range interactions present in the system.

Baishali Chakraborty; Kumar S. Gupta; Siddhartha Sen

2014-03-20

269

EDITORIAL: Topological data analysis Topological data analysis

NASA Astrophysics Data System (ADS)

Inverse problems can be defined as the area of mathematics that attempts to reconstruct a physical or mathematical object from derived data. Frequently, this means the evaluation of parameters or other numerical quantities (such as eigenvalues) that characterize or provide information about the system. There are, however, other aspects of a system that are important, but are not as readily summarized by numerical quantities. If one considers observations of diabetic patients (using metabolic quantities), one will find that the data breaks up into components, or pieces, corresponding to distinct forms of the disease. The decomposition of data sets into disjoint pieces, or clustering, is an aspect of the study of the shape of the data, albeit one that has been extensively studied. A more complex notion of shape appears in observations of a predator-prey system governed by a Lotka-Volterra equation. One would find that exact observations, consisting of (prey population, predator population) pairs, appear to lie along a simple closed curve in the plane. The fact that the data lies along such a closed curve is an important piece of information, since it suggests that the system displays recurrent behavior. If one did not know, a priori, that the system is governed by a Lotka-Volterra equation, then it would not be immediately obvious that the system is undergoing recurrent motion, and this deduction would constitute a significant insight. In this case, it is again the shape of the data, namely the fact that it lies on a simple closed curve, which is the key insight. Shape is a somewhat nebulous concept, which at first blush may be too intuitive to make precise mathematically, and describe quantitatively. Within pure mathematics, the disciplines of topology and differential geometry are designed exactly to address this problem. They provide explicit signatures which, in precise senses, quantify and describe the shape of a geometric object. In addition, they provide methods for discretizing and compressing the information present in a geometric object so as to provide a useful, small representation of the object. The articles in this special issue are concerned with the applications of topology to the analysis of data sets. The adaptation of topological techniques from pure mathematics to the study of data from real systems is a project which has been undertaken during the past two decades, and the present volume contains various contributions to that project. At the current state of development, homology and persistence are two of the most popular topological techniques used in this context. Homology goes back to the beginnings of topology in Poincaré's influential papers. It is the idea that the connectivity of a space is determined by its cycles of different dimensions, and that these cycles organize themselves into abelian groups, called homology groups. Better known than these groups are their ranks, the Betti numbers of the space, which are non-negative integers that count the number of independent cycles in each dimension. To give an example, the zeroth Betti number counts the components, and the first counts the loops. A crucial feature of homology groups is that, given a reasonably explicit description of a space, their computation is an exercise in linear algebra. Even better known than the Betti numbers is the Euler characteristic, which we know from Poincaré's work, is equal to the alternating sum of the Betti numbers, which can be computed without computing the homology groups themselves. To give evidence that these numbers have relevant practical applications, we mention that integrating the Euler characteristic over a domain with sensor information can be used to count objects in the domain. This alone would not explain the popularity of homology groups, which we see rooted in the fact that they hit a sweet-spot that offers relatively strong discriminative power, and a clear intuitive meaning, all at a surprisingly low computational cost. Even these desirable qualities would not be sufficient if it were not pos

Epstein, Charles; Carlsson, Gunnar; Edelsbrunner, Herbert

2011-12-01

270

Interim President R. Bowen Loftin requested that the Task Force on Enlightened and Shared consensus on the definition of enlightened and shared governance; assess the current status of enlightened of enlightened and shared governance for our University. The task force would like to share its working draft

271

Cosmology from Topological Defects

The potential role of cosmic topological defects has raised interest in the astrophysical community for many years now. In this set of notes, we give an introduction to the subject of cosmic topological defects and some of their possible observable signatures. We begin with a review of the basics of general defect formation and evolution, we briefly comment on some general features of conducting cosmic strings and vorton formation, as well as on the possible role of defects as dark energy, to end up with cosmic structure formation from defects and some specific imprints in the cosmic microwave background radiation from simulated cosmic strings. A detailed, pedagogical explanation of the mechanism underlying the tiny level of polarization discovered in the cosmic microwave background by the DASI collaboration (and recently confirmed by WMAP) is also given, and a first rough comparison with some predictions from defects is provided.

Alejandro Gangui

2003-03-21

272

A method enables the topology of an acyclic fully propagated network to be discovered. A list of switches that comprise the network is formed and the MAC address cache for each one of the switches is determined. For each pair of switches, from the MAC address caches the remaining switches that see the pair of switches are located. For each pair of switches the remaining switches are determined that see one of the pair of switches on a first port and the second one of the pair of switches on a second port. A list of insiders is formed for every pair of switches. It is determined whether the insider for each pair of switches is a graph edge and adjacent ones of the graph edges are determined. A symmetric adjacency matrix is formed from the graph edges to represent the topology of the data link network.

Quist, Daniel A. (Los Alamos, NM); Gavrilov, Eugene M. (Los Alamos, NM); Fisk, Michael E. (Jemez, NM)

2008-01-15

273

Isospin of topological defects in Dirac systems

NASA Astrophysics Data System (ADS)

We study the Dirac quasiparticles in d-dimensional lattice systems of electrons in the presence of domain walls (d=1), vortices (d=2), or hedgehogs (d=3) of superconducting and/or insulating, order parameters, which appear as mass terms in the Dirac equation. Such topological defects have been known to carry nontrivial quantum numbers, such as charge and spin. Here we discuss their additional internal degree of freedom: irrespective of the dimensionality of space and the nature of orders that support the defect, an extra mass order parameter is found to emerge in their core. Six linearly independent local orders, which close two mutually commuting three-dimensional Clifford algebras, are proven to be in general possible. We show how the particle-hole symmetry restricts the defects to always carry the quantum numbers of a single effective isospin 1/2, quite independently of the values of their electric charge or true spin. Examples of this new degree of freedom in graphene and on surfaces of topological insulators are discussed.

Herbut, Igor F.

2012-02-01

274

Topological confinement and superconductivity

We derive a Kondo Lattice model with a correlated conduction band from a two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence of a robust pairing mechanism in a model that only contains repulsive interactions. The mechanism is due to topological confinement and results from the interplay between antiferromagnetism and delocalization. By using Density-Matrix-Renormalization-Group (DMRG) we demonstrate that this mechanism leads to dominant superconducting correlations in aID-system.

Al-hassanieh, Dhaled A [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory

2008-01-01

275

Topological quantum computation

The theory of quantum computation can be constructed from the abstract study\\u000aof anyonic systems. In mathematical terms, these are unitary topological\\u000amodular functors. They underlie the Jones polynomial and arise in\\u000aWitten-Chern-Simons theory. The braiding and fusion of anyonic excitations in\\u000aquantum Hall electron liquids and 2D-magnets are modeled by modular functors,\\u000aopening a new possibility for the realization

Michael H. Freedman; Alexei Kitaev; Michael J. Larsen; Zhenghan Wang; L. D. Landau; Michael H. Freedman

2002-01-01

276

Topological phases reviewed: The Aharonov Bohm, Aharonov Casher, and He McKellar Wilkens phases

There are three topological phases related to electromagnetic interactions in quantum mechanics: 1. The Aharonov Bohm phase acquired when a charged particle encircles a magnetic field but travels through a field free region. 2. The Aharonov Casher phase acquired when a magnetic dipole encircles electric charges but travels through a charge free region. 3. The He McKellar Wilkens phase acquired when an electric dipole encircles magnetic charges but travels through a charge free region. We review the conditions under which these phases are indeed topological and their experimental realisation. Because the He McKellar Wilkens phase has been recently observed we pay particular attention to how the basic concept of 'an electric dipole encircles magnetic charges' was realised experimentally, and discuss possible future experimental realisations.

McKellar, B. H. J. [ARC Centre of Excellence for Particle Physics at the Terrascale, School of Physics, University of Melbourne (Australia); He, X-G. [Department of Physics, National Taiwan University, Taipei, Taiwan (China); Klein, A. G. [School of Physics, University of Melbourne (Australia)

2014-03-05

277

Transportation Network Topologies

NASA Technical Reports Server (NTRS)

A discomforting reality has materialized on the transportation scene: our existing air and ground infrastructures will not scale to meet our nation's 21st century demands and expectations for mobility, commerce, safety, and security. The consequence of inaction is diminished quality of life and economic opportunity in the 21st century. Clearly, new thinking is required for transportation that can scale to meet to the realities of a networked, knowledge-based economy in which the value of time is a new coin of the realm. This paper proposes a framework, or topology, for thinking about the problem of scalability of the system of networks that comprise the aviation system. This framework highlights the role of integrated communication-navigation-surveillance systems in enabling scalability of future air transportation networks. Scalability, in this vein, is a goal of the recently formed Joint Planning and Development Office for the Next Generation Air Transportation System. New foundations for 21st thinking about air transportation are underpinned by several technological developments in the traditional aircraft disciplines as well as in communication, navigation, surveillance and information systems. Complexity science and modern network theory give rise to one of the technological developments of importance. Scale-free (i.e., scalable) networks represent a promising concept space for modeling airspace system architectures, and for assessing network performance in terms of scalability, efficiency, robustness, resilience, and other metrics. The paper offers an air transportation system topology as framework for transportation system innovation. Successful outcomes of innovation in air transportation could lay the foundations for new paradigms for aircraft and their operating capabilities, air transportation system architectures, and airspace architectures and procedural concepts. The topology proposed considers air transportation as a system of networks, within which strategies for scalability of the topology may be enabled by technologies and policies. In particular, the effects of scalable ICNS concepts are evaluated within this proposed topology. Alternative business models are appearing on the scene as the old centralized hub-and-spoke model reaches the limits of its scalability. These models include growth of point-to-point scheduled air transportation service (e.g., the RJ phenomenon and the Southwest Effect). Another is a new business model for on-demand, widely distributed, air mobility in jet taxi services. The new businesses forming around this vision are targeting personal air mobility to virtually any of the thousands of origins and destinations throughout suburban, rural, and remote communities and regions. Such advancement in air mobility has many implications for requirements for airports, airspace, and consumers. These new paradigms could support scalable alternatives for the expansion of future air mobility to more consumers in more places.

Holmes, Bruce J.; Scott, John

2004-01-01

278

Transportation Network Topologies

NASA Technical Reports Server (NTRS)

A discomforting reality has materialized on the transportation scene: our existing air and ground infrastructures will not scale to meet our nation's 21st century demands and expectations for mobility, commerce, safety, and security. The consequence of inaction is diminished quality of life and economic opportunity in the 21st century. Clearly, new thinking is required for transportation that can scale to meet to the realities of a networked, knowledge-based economy in which the value of time is a new coin of the realm. This paper proposes a framework, or topology, for thinking about the problem of scalability of the system of networks that comprise the aviation system. This framework highlights the role of integrated communication-navigation-surveillance systems in enabling scalability of future air transportation networks. Scalability, in this vein, is a goal of the recently formed Joint Planning and Development Office for the Next Generation Air Transportation System. New foundations for 21PstP thinking about air transportation are underpinned by several technological developments in the traditional aircraft disciplines as well as in communication, navigation, surveillance and information systems. Complexity science and modern network theory give rise to one of the technological developments of importance. Scale-free (i.e., scalable) networks represent a promising concept space for modeling airspace system architectures, and for assessing network performance in terms of scalability, efficiency, robustness, resilience, and other metrics. The paper offers an air transportation system topology as framework for transportation system innovation. Successful outcomes of innovation in air transportation could lay the foundations for new paradigms for aircraft and their operating capabilities, air transportation system architectures, and airspace architectures and procedural concepts. The topology proposed considers air transportation as a system of networks, within which strategies for scalability of the topology may be enabled by technologies and policies. In particular, the effects of scalable ICNS concepts are evaluated within this proposed topology. Alternative business models are appearing on the scene as the old centralized hub-and-spoke model reaches the limits of its scalability. These models include growth of point-to-point scheduled air transportation service (e.g., the RJ phenomenon and the 'Southwest Effect'). Another is a new business model for on-demand, widely distributed, air mobility in jet taxi services. The new businesses forming around this vision are targeting personal air mobility to virtually any of the thousands of origins and destinations throughout suburban, rural, and remote communities and regions. Such advancement in air mobility has many implications for requirements for airports, airspace, and consumers. These new paradigms could support scalable alternatives for the expansion of future air mobility to more consumers in more places.

Holmes, Bruce J.; Scott, John M.

2004-01-01

279

Continuous-variable topological codes

NASA Astrophysics Data System (ADS)

Topological code is a stabilizer quantum error correcting code whose generators are local but logical operators are topologically nontrivial and nonlocal. It offers interesting features such as the homological deformations of string operators and anyonic excitations on it. Topological codes are also closely related to the “topological order,” which has been an important concept in condensed-matter physics. In this paper, we consider continuous-variable versions of topological codes, including the toric code by Kitaev [A. Y. Kitaev, Ann. Phys.APNYA60003-491610.1016/S0003-4916(02)00018-0 303, 2 (2003)] with a single type of stabilizer on the checkerboard lattice, and the color code by Bombin and Martin-Delgado [H. Bombin and M. A. Martin-Delgado, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.97.180501 97, 180501 (2006)]. We show that it is possible to consider continuous-variable analog of these topological codes.

Morimae, Tomoyuki

2013-10-01

280

On topological terms in the O(3) nonlinear sigma model

NASA Astrophysics Data System (ADS)

Topological terms in the O(3) nonlinear sigma model in (1+1) and (2+1) dimensions are re-examined based on the description of the SU(2)-valued field g. We first show that the topological soliton term in (1+1) dimensions arises from the unitary representations of the group characterizing the global structure of the symmetry inherent in the description, in a manner analogous to the appearance of the ?-term in Yang-Mills theory in (3+1) dimensions. We then present a detailed argument as to why the conventional Hopf term, which is the topological counterpart in (2+1) dimensions and has been widely used to realize fractional spin and statistics, is ill-defined unless the soliton charge vanishes. We show how this restriction can be lifted by means of a procedure proposed recently, and provide its physical interpretation as well.

Tsurumaru, Toyohiro; Tsutsui, Izumi

1999-08-01

281

Chiral topological insulator on Nambu 3-algebraic geometry

NASA Astrophysics Data System (ADS)

Chiral topological insulator (AIII-class) with Landau levels is constructed based on the Nambu 3-algebraic geometry. We clarify the geometric origin of the chiral symmetry of the AIII-class topological insulator in the context of non-commutative geometry of 4D quantum Hall effect. The many-body groundstate wavefunction is explicitly derived as a (l,l,l-1) Laughlin-Halperin type wavefunction with unique K-matrix structure. Fundamental excitation is identified with anyonic string-like object with fractional charge 1/(2(+1). The Hall effect of the chiral topological insulators turns out be a color version of Hall effect, which exhibits a dual property of the Hall and spin-Hall effects.

Hasebe, Kazuki

2014-09-01

282

Chiral Topological Insulator on Nambu 3-Algebraic Geometry

Chiral topological insulator (AIII-class) with Landau levels is constructed based on the Nambu 3-algebraic geometry. We clarify the geometric origin of the chiral symmetry of the AIII-class topological insulator in the context of non-commutative geometry of 4D quantum Hall effect. The many-body groundstate wavefunction is explicitly derived as a $(l,l,l-1)$ Laughlin-Halperin type wavefunction with unique $K$-matrix structure. Fundamental excitation is identified with anyonic string-like object with fractional charge ${1}/({1+2(l-1)^2})$. The Hall effect of the chiral topological insulators turns out be a color version of Hall effect, which exhibits a dual property of the Hall and spin-Hall effects.

Kazuki Hasebe

2014-08-02

283

Topology discovery for large ethernet networks

Accurate network topology information is important for both network management and application performance prediction. Most topology discovery research has focused on wide-area networks and examined topology only at the IP router level, ignoring the need for LAN topology information. Recent work has demonstrated that bridged Ethernet topology can be determined using standard SNMP MIBs; however, these algorithms require each bridge

Bruce Lowekamp; David R. O'Hallaron; Thomas R. Gross

2001-01-01

284

Detecting Communities Based on Network Topology

NASA Astrophysics Data System (ADS)

Network methods have had profound influence in many domains and disciplines in the past decade. Community structure is a very important property of complex networks, but the accurate definition of a community remains an open problem. Here we defined community based on three properties, and then propose a simple and novel framework to detect communities based on network topology. We analyzed 16 different types of networks, and compared our partitions with Infomap, LPA, Fastgreedy and Walktrap, which are popular algorithms for community detection. Most of the partitions generated using our approach compare favorably to those generated by these other algorithms. Furthermore, we define overlapping nodes that combine community structure with shortest paths. We also analyzed the E. Coli. transcriptional regulatory network in detail, and identified modules with strong functional coherence.

Liu, Wei; Pellegrini, Matteo; Wang, Xiaofan

2014-07-01

285

Detecting Communities Based on Network Topology

Network methods have had profound influence in many domains and disciplines in the past decade. Community structure is a very important property of complex networks, but the accurate definition of a community remains an open problem. Here we defined community based on three properties, and then propose a simple and novel framework to detect communities based on network topology. We analyzed 16 different types of networks, and compared our partitions with Infomap, LPA, Fastgreedy and Walktrap, which are popular algorithms for community detection. Most of the partitions generated using our approach compare favorably to those generated by these other algorithms. Furthermore, we define overlapping nodes that combine community structure with shortest paths. We also analyzed the E. Coli. transcriptional regulatory network in detail, and identified modules with strong functional coherence. PMID:25033828

Liu, Wei; Pellegrini, Matteo; Wang, Xiaofan

2014-01-01

286

Effective theory of fractional topological insulators in two spatial dimensions

NASA Astrophysics Data System (ADS)

Electrons subjected to a strong spin-orbit coupling in two spatial dimensions could form fractional incompressible quantum liquids without violating the time-reversal symmetry. Here, we construct a Lagrangian description of such fractional topological insulators by combining the available experimental information on potential host materials and the fundamental principles of quantum field theory. This Lagrangian is a Landau-Ginzburg theory of spinor fields, enhanced by a topological term that implements a state-dependent fractional statistics of excitations whenever both particles and vortices are incompressible. The spin-orbit coupling is captured by an external static SU(2) gauge field. The presence of spin conservation or emergent U(1) symmetries would reduce the topological term to the Chern-Simons effective theory tailored to the ensuing quantum Hall state. However, the Rashba spin-orbit coupling in solid-state materials does not conserve spin. We predict that it can nevertheless produce incompressible quantum liquids with topological order but without a quantized Hall conductivity. We discuss two examples of such liquids whose description requires a generalization of the Chern-Simons theory. One is an Abelian Laughlin-type state, while the other has a new kind of non-Abelian many-body entanglement. Their quasiparticles exhibit fractional spin-dependent exchange statistics, and have fractional quantum numbers derived from the electron's charge and spin according to their transformations under time reversal. In addition to conventional phases of matter, the proposed topological Lagrangian can capture a broad class of hierarchical Abelian and non-Abelian topological states, involving particles with arbitrary spin or general emergent SU(N) charges.

Nikoli?, Predrag

2013-06-01

287

This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

Albrecht, J; Babu, K; Bernstein, R H; Blum, T; Brown, D N; Casey, B C K; Cheng, C -h; Cirigliano, V; Cohen, A; Deshpande, A; Dukes, E C; Echenard, B; Gaponenko, A; Glenzinski, D; Gonzalez-Alonso, M; Grancagnolo, F; Grossman, Y; Harnik, R; Hitlin, D G; Kiburg, B; Knoepfe, K; Kumar, K; Lim, G; Lu, Z -T; McKeen, D; Miller, J P; Ramsey-Musolf, M; Ray, R; Roberts, B L; Rominsky, M; Semertzidis, Y; Stoeckinger, D; Talman, R; Van De Water, R; Winter, P

2013-01-01

288

NSDL National Science Digital Library

In this activity, learners explore how objects can have positive, negative, or neutral charges, which attract, repel and move between objects. Learners charge various materials and observe their interactions. Winter is an ideal time to perform these experiments (because there is less water vapor in the air); if it is humid, use a hair dryer to dry the objects, surfaces, and air around the work area.

2012-06-26

289

#12;Â· Â· Â· Â· #12;Â· Â· f1 f2 f3 f2 f3 f1 #12;comp 1 comp 2 f1 f2 f3 #12;f2 f2 Toy Topology f1 f1 1 1 Comp 4 Chan 1 Chan 2 Chan 3 Chan 2 Path SelectionChannel Assignment No of available channels = 35 No of channels 10Mbps component based link based flow based 0 0.5 1 1.5 2 2.5 3 3.5 4 1 2 3 4 5 6 7 8 Delay

Sivakumar, Raghupathy

290

Generalization of topological indices

NASA Astrophysics Data System (ADS)

A generalized (molecular) graph-theoretical matrix is introduced in such a way that the adjacency and distance matrices of (molecular) graphs are particular cases of it. By using this matrix, two new molecular graph-theoretical vectors and a vector-matrix-vector multiplication procedure, a generalized invariant is introduced. This invariant permits a generalization of some of the classical topological indices (TIs). Thus, Wiener W index, Zagreb M1 and M2 indices, Balaban J index, Harary H number, Randic ? index and valence connectivity index ?v resulted as particular cases of an infinite set of molecular descriptors that can be derived from the same invariant.

Estrada, Ernesto

2001-03-01

291

Topological control of level set method depending on topology constraints

In this paper, a novel framework combining the Chan–Vese active contour segmentation model with topology control mechanism is proposed. The novel framework can control active contours to capture specified objects in the applied images. Geometric active contours implemented by the traditional level set method can adaptively split and merge, but it is difficult to handle the topological constraints of the

Chih-yu Hsu; Chih-hung Yang; Hui-ching Wang

2008-01-01

292

Scalar Topology in Visual Data Analysis

Scalar Topology in Visual Data Analysis Theory and Motivational Applications #12;Isosurface (Data courtesy of Hamish Carr, University College Dublin) #12;Isosurface Topology Changes Occur at Critical Points (Data courtesy of Hamish Carr, University College Dublin) #12;Isosurface Topology Changes

293

GENERAL: Topological Quantization of Instantons in SU(2) Yang Mills Theory

NASA Astrophysics Data System (ADS)

By decomposing SU(2) gauge potential in four-dimensional Euclidean SU(2) Yang-Mills theory in a new way, we find that the instanton number related to the isospin defects of a doublet order parameter can be topologically quantized by the Hopf index and Brouwer degree. It is also shown that the instanton number is just the sum of the topological charges of the isospin defects in the non-trivial sector of Yang-Mills theory.

Zhong, Wo-Jun; Duan, Yi-Shi

2008-05-01

294

A new topology for single phase UPS systems

This paper presents a new converter topology, based on a single switch AC\\/DC or DC\\/DC boost converter combined with a half bridge inverter, suitable for on-line single phase UPS systems. The converter uses only four active switches, including the one for maintaining the charge of storage battery, to realize very desirable features. These include sinusoidal input currents, a common neutral

Gui-Jia Su; Tetuhiko Ohno

1997-01-01

295

Charge without charge in quarks

With appropriate gauge transformations, field can replace electric charge in quarks. Classical quarks, in a necessary non-gauge invariant formulation, are used for illustration, bringing to the fore the lim- itations of the usual electric charge densities for single particles in Coulomb equations. The results are encouraging; the solutions for the Coulomb potentials apply individually to each quark in a shell struc- ture. A remarkably simple relation emerges between the Coulomb and weak potentials.

Harry Schiff

2013-08-06

296

The tree structure is currently the accepted paradigm to represent evolutionary relationships between organisms, species or other taxa. However, horizontal, or reticulate, genomic exchanges are pervasive in nature and confound characterization of phylogenetic trees. Drawing from algebraic topology, we present a unique evolutionary framework that comprehensively captures both clonal and reticulate evolution. We show that whereas clonal evolution can be summarized as a tree, reticulate evolution exhibits nontrivial topology of dimension greater than zero. Our method effectively characterizes clonal evolution, reassortment, and recombination in RNA viruses. Beyond detecting reticulate evolution, we succinctly recapitulate the history of complex genetic exchanges involving more than two parental strains, such as the triple reassortment of H7N9 avian influenza and the formation of circulating HIV-1 recombinants. In addition, we identify recurrent, large-scale patterns of reticulate evolution, including frequent PB2-PB1-PA-NP cosegregation during avian influenza reassortment. Finally, we bound the rate of reticulate events (i.e., 20 reassortments per year in avian influenza). Our method provides an evolutionary perspective that not only captures reticulate events precluding phylogeny, but also indicates the evolutionary scales where phylogenetic inference could be accurate. PMID:24170857

Chan, Joseph Minhow; Carlsson, Gunnar; Rabadan, Raul

2013-11-12

297

Topological implications of inhomogeneity

NASA Astrophysics Data System (ADS)

The approximate homogeneity of spatial sections of the Universe is well supported observationally, but the inhomogeneity of the spatial sections is even better supported. Here, we consider the implications of inhomogeneity in dust models for the connectedness of spatial sections at early times. We consider a nonglobal Lemaître-Tolman-Bondi (LTB) model designed to match observations, a more general, heuristic model motivated by the former, and two specific, global LTB models. We propose that the generic class of solutions of the Einstein equations projected back in time from the spatial section at the present epoch includes subclasses in which the spatial section evolves (with increasing time) smoothly (i) from being disconnected to being connected, or (ii) from being simply connected to being multiply connected, where the coordinate system is comoving and synchronous. We show that (i) and (ii) each contain at least one exact solution. These subclasses exist because the Einstein equations allow nonsimultaneous big bang times. The two types of topology evolution occur over time slices that include significantly postquantum epochs if the bang time varies by much more than a Planck time. In this sense, it is possible for cosmic topology evolution to be “mostly” classical.

Roukema, Boudewijn F.; Blanlœil, Vincent; Ostrowski, Jan J.

2013-02-01

298

The tree structure is currently the accepted paradigm to represent evolutionary relationships between organisms, species or other taxa. However, horizontal, or reticulate, genomic exchanges are pervasive in nature and confound characterization of phylogenetic trees. Drawing from algebraic topology, we present a unique evolutionary framework that comprehensively captures both clonal and reticulate evolution. We show that whereas clonal evolution can be summarized as a tree, reticulate evolution exhibits nontrivial topology of dimension greater than zero. Our method effectively characterizes clonal evolution, reassortment, and recombination in RNA viruses. Beyond detecting reticulate evolution, we succinctly recapitulate the history of complex genetic exchanges involving more than two parental strains, such as the triple reassortment of H7N9 avian influenza and the formation of circulating HIV-1 recombinants. In addition, we identify recurrent, large-scale patterns of reticulate evolution, including frequent PB2-PB1-PA-NP cosegregation during avian influenza reassortment. Finally, we bound the rate of reticulate events (i.e., 20 reassortments per year in avian influenza). Our method provides an evolutionary perspective that not only captures reticulate events precluding phylogeny, but also indicates the evolutionary scales where phylogenetic inference could be accurate. PMID:24170857

Chan, Joseph Minhow; Carlsson, Gunnar; Rabadan, Raul

2013-01-01

299

A natural topological insulator.

The earth's crust and outer space are rich sources of technologically relevant materials which have found application in a wide range of fields. Well-established examples are diamond, one of the hardest known materials, or graphite as a suitable precursor of graphene. The ongoing drive to discover novel materials useful for (opto)electronic applications has recently drawn strong attention to topological insulators. Here, we report that Kawazulite, a mineral with the approximate composition Bi2(Te,Se)2(Se,S), represents a naturally occurring topological insulator whose electronic properties compete well with those of its synthetic counterparts. Kawazulite flakes with a thickness of a few tens of nanometers were prepared by mechanical exfoliation. They exhibit a low intrinsic bulk doping level and correspondingly a sizable mobility of surface state carriers of more than 1000 cm(2)/(V s) at low temperature. Based on these findings, further minerals which due to their minimized defect densities display even better electronic characteristics may be identified in the future. PMID:23438015

Gehring, P; Benia, H M; Weng, Y; Dinnebier, R; Ast, C R; Burghard, M; Kern, K

2013-03-13

300

We analyze the way topological constraints and inhomogeneity in the excitability influence the dynamics of spiral waves on spheres and punctured spheres of excitable media. We generalize the definition of an index such that it characterizes not only each spiral but also each hole in punctured, oriented, compact, two-dimensional differentiable manifolds and show that the sum of the indices is

Jörn Davidsen; Leon Glass; Raymond Kapral

2004-01-01

301

In this paper, a new method in order to achieve the geometrical and topological definition of extracted road networks is presented. Starting from a raster binary image where a road network is depicted, this algorithm seeks the automatic raster – vector conversion based on skeleton extraction and graph theory and using GIS database if it is available. The last goal

Juan B. Mena

2006-01-01

302

Preprint Digital imaging: a unified topological framework LoÂ¨ic Mazo Â· Nicolas Passat Â· Michel related to the definition of LoÂ¨ic Mazo, Nicolas Passat, Christian Ronse UniversitÂ´e de Strasbourg, LSIIT, UMR CNRS 7005, France Tel.: +33-368854413 Fax: +33-368854455 E-mail: loic.mazo@unistra.fr LoÂ¨ic Mazo

Paris-Sud XI, UniversitÃ© de

303

Renormalizability of Topologically Massive Gravity

We consider renormalizability of topologically massive gravity in three space-time dimensions. With a usual parametrization of the metric tensor, we establish the statement that topologically massive gravity is in fact renormalizable. In this proof, we make use of not only a recently found, new infrared regularization method of scalar mode but also a covariant ultraviolet regulator with a specific combination

Ichiro Oda

2009-01-01

304

Topology and intelligent data analysis

A broad range of mathematical techniques, ranging from statistics to fuzzy logic, have been used to great advantage in intelligent data analysis. Topology - the fundamental mathematics of shape - has to date been conspicuously absent from this repertoire. This paper shows how topology, properly reformulated for a finite-precision world, can be useful in intelligent data analysis tasks.

V. Robins; J. Abernethy; E. Bradley

305

Topology and Intelligent Data Analysis

Abstract. A broad range of mathematical techniques, ranging from statistics to fuzzy logic, have been used to great advantage in intelligent data analysis. Topology – the fundamental,mathematics,of shape – has to date been conspicuously,absent from this repertoire. This paper shows how topology, properly reformulated for a finite-precision world, can be useful in intelligent data analysis tasks.

V. Robins; Jennifer Abernethy; N. Rooney; Elizabeth Bradley

2003-01-01

306

Finding topological center of a geographic space via road network

NASA Astrophysics Data System (ADS)

Previous studies show that the center of a geographic space is of great importance in urban and regional studies, including study of population distribution, urban growth modeling, and scaling properties of urban systems, etc. But how to well define and how to efficiently extract the center of a geographic space are still largely unknown. Recently, Jiang et al. have presented a definition of topological center by their block detection (BD) algorithm. Despite the fact that they first introduced the definition and discovered the 'true center', in human minds, their algorithm left several redundancies in its traversal process. Here, we propose an alternative road-cycle detection (RCD) algorithm to find the topological center, which extracts the outmost road-cycle recursively. To foster the application of the topological center in related research fields, we first reproduce the BD algorithm in Python (pyBD), then implement the RCD algorithm in two ways: the ArcPy implementation (arcRCD) and the Python implementation (pyRCD). After the experiments on twenty-four typical road networks, we find that the results of our RCD algorithm are consistent with those of Jiang's BD algorithm. We also find that the RCD algorithm is at least seven times more efficient than the BD algorithm on all the ten typical road networks.

Gao, Liang; Miao, Yanan; Qin, Yuhao; Zhao, Xiaomei; Gao, Zi-You

2015-02-01

307

Code of Federal Regulations, 2013 CFR

... Cantline means the v-shaped groove between two abutting...than 375 kw; or (3) any oil-fired boiler or fuel unit...part, includes the person in charge of an unmanned vessel or barge...materials, coal, lubricants, and oils. This definition does not...

2013-10-01

308

Code of Federal Regulations, 2012 CFR

... Cantline means the v-shaped groove between two abutting...than 375 kw; or (3) any oil-fired boiler or fuel unit...part, includes the person in charge of an unmanned vessel or barge...materials, coal, lubricants, and oils. This definition does not...

2012-10-01

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310

Code of Federal Regulations, 2011 CFR

... Cantline means the v-shaped groove between two abutting...than 375 kw; or (3) any oil-fired boiler or fuel unit...part, includes the person in charge of an unmanned vessel or barge...materials, coal, lubricants, and oils. This definition does not...

2011-10-01

311

Code of Federal Regulations, 2012 CFR

...RECORDS Production or Disclosure of Records Under the Freedom of Information Act, 5 U.S.C. 552 Charges for Search and Reproduction § 2502.11 Definitions. For the purpose of this part: (a) All the terms defined in the Freedom of...

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Code of Federal Regulations, 2011 CFR

...RECORDS Production or Disclosure of Records Under the Freedom of Information Act, 5 U.S.C. 552 Charges for Search and Reproduction § 2502.11 Definitions. For the purpose of this part: (a) All the terms defined in the Freedom of...

2011-01-01

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315

Code of Federal Regulations, 2012 CFR

...Contained in Pre-Charged Equipment or Closed-Cell Foams § 98.438 Definitions...refrigerator, chiller, or freezer. Closed-cell foam means any foam product, excluding...foam, that is constructed with a closed-cell structure and a blowing agent...

2012-07-01

316

Code of Federal Regulations, 2013 CFR

...Contained in Pre-Charged Equipment or Closed-Cell Foams § 98.438 Definitions...refrigerator, chiller, or freezer. Closed-cell foam means any foam product, excluding...foam, that is constructed with a closed-cell structure and a blowing agent...

2013-07-01

317

Code of Federal Regulations, 2011 CFR

...Contained in Pre-Charged Equipment or Closed-Cell Foams § 98.438 Definitions...refrigerator, chiller, or freezer. Closed-cell foam means any foam product, excluding...foam, that is constructed with a closed-cell structure and a blowing agent...

2011-07-01

318

Concept Model on Topological Learning

NASA Astrophysics Data System (ADS)

We discuss a new model for concept based on topological learning, where the learning process on the neural network is represented by mathematical topology. The topological learning of neural networks is summarized by a quotient of input space and the hierarchical step induces a tree where each node corresponds to a quotient. In general, the concept acquisition is a difficult problem, but the emotion for a subject is represented by providing the questions to a person. Therefore, a kind of concept is captured by such data and the answer sheet can be mapped into a topology consisting of trees. In this paper, we will discuss a way of mapping the emotional concept to a topological learning model.

Ae, Tadashi; Kioi, Kazumasa

2010-11-01

319

Topological Characterization of Fractional Quantum Hall Ground States from Microscopic Hamiltonians

NASA Astrophysics Data System (ADS)

We show how to numerically calculate several quantities that characterize topological order starting from a microscopic fractional quantum Hall Hamiltonian. To find the set of degenerate ground states, we employ the infinite density matrix renormalization group method based on the matrix-product state representation of fractional quantum Hall states on an infinite cylinder. To study localized quasiparticles of a chosen topological charge, we use pairs of degenerate ground states as boundary conditions for the infinite density matrix renormalization group. We then show that the wave function obtained on the infinite cylinder geometry can be adapted to a torus of arbitrary modular parameter, which allows us to explicitly calculate the non-Abelian Berry connection associated with the modular T transformation. As a result, the quantum dimensions, topological spins, quasiparticle charges, chiral central charge, and Hall viscosity of the phase can be obtained using data contained entirely in the entanglement spectrum of an infinite cylinder.

Zaletel, Michael P.; Mong, Roger S. K.; Pollmann, Frank

2013-06-01

320

Topological characterization of fractional quantum Hall ground states from microscopic Hamiltonians.

We show how to numerically calculate several quantities that characterize topological order starting from a microscopic fractional quantum Hall Hamiltonian. To find the set of degenerate ground states, we employ the infinite density matrix renormalization group method based on the matrix-product state representation of fractional quantum Hall states on an infinite cylinder. To study localized quasiparticles of a chosen topological charge, we use pairs of degenerate ground states as boundary conditions for the infinite density matrix renormalization group. We then show that the wave function obtained on the infinite cylinder geometry can be adapted to a torus of arbitrary modular parameter, which allows us to explicitly calculate the non-Abelian Berry connection associated with the modular T transformation. As a result, the quantum dimensions, topological spins, quasiparticle charges, chiral central charge, and Hall viscosity of the phase can be obtained using data contained entirely in the entanglement spectrum of an infinite cylinder. PMID:25167520

Zaletel, Michael P; Mong, Roger S K; Pollmann, Frank

2013-06-01

321

Charge Falling Through a Charged Ring Model

NSDL National Science Digital Library

The Charge Falling Through a Charged Ring shows dynamics of a charged ball as it is released and falls through a ring of charge. The ball and the ring can be charged with a positive blue) or a (red) negative charge.

Krizaj, Dejan

2010-11-09

322

7 CFR 62.301 - Payment of fees and other charges.

Code of Federal Regulations, 2011 CFR

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2011-01-01

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7 CFR 62.301 - Payment of fees and other charges.

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Payment of fees and other charges. 62.301 Section 62.301 Agriculture...Systems Verification Programs Definitions Charges for Service § 62.301 Payment of fees and other charges. Fees and other charges for QSVP...

2013-01-01

325

Implementation of a 1GHZ frontend using transform domain charge sampling techniques

) . . . . . . . . . . . . . . . . 6 B. Transform Domain (TD) Sampling . . . . . . . . . . . . . 7 III CHARGE SAMPLING : : : : : : : : : : : : : : : : : : : : : : : 9 IV FRONT END ARCHITECTURE : : : : : : : : : : : : : : : : : 13 A. System Simulations in MATLAB... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 25 14 Step by step topology operation : : : : : : : : : : : : : : : : : : : : : 26 15 Triangular approximation of the integration window for the over- lap topology : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 27 16 MATLAB comparison...

Kulkarni, Mandar Shashikant

2009-05-15

326

Azimuthal Charged-Particle Correlations and Possible Local Strong Parity Violation

Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along ...

Redwine, Robert P.

327

Higher Hochschild Homology, Topological Chiral Homology and Factorization Algebras

NASA Astrophysics Data System (ADS)

We study the higher Hochschild functor, factorization algebras and their relationship with topological chiral homology. To this end, we emphasize that the higher Hochschild complex is a functor sSet ? × CDGA ? where sSet and CDGA ? are the (?,1)-categories of simplicial sets and commutative differential graded algebras, and give an axiomatic characterization of this functor. From the axioms, we deduce several properties and computational tools for this functor. We study the relationship between the higher Hochschild functor and factorization algebras by showing that, in good cases, the Hochschild functor determines a constant commutative factorization algebra. Conversely, every constant commutative factorization algebra is naturally equivalent to a Hochschild chain factorization algebra. Similarly, we study the relationship between the above concepts and topological chiral homology. In particular, we show that on their common domains of definition, the higher Hochschild functor is naturally equivalent to topological chiral homology. Finally, we prove that topological chiral homology determines a locally constant factorization algebra and, further, that this functor induces an equivalence between locally constant factorization algebras on a manifold and (local system of) E n -algebras.

Ginot, Grégory; Tradler, Thomas; Zeinalian, Mahmoud

2014-03-01

328

Transportation Network Topologies

NASA Technical Reports Server (NTRS)

The existing U.S. hub-and-spoke air transportation system is reaching saturation. Major aspects of the current system, such as capacity, safety, mobility, customer satisfaction, security, communications, and ecological effects, require improvements. The changing dynamics - increased presence of general aviation, unmanned autonomous vehicles, military aircraft in civil airspace as part of homeland defense - contributes to growing complexity of airspace. The system has proven remarkably resistant to change. NASA Langley Research Center and the National Institute of Aerospace conducted a workshop on Transportation Network Topologies on 9-10 December 2003 in Williamsburg, Virginia. The workshop aimed to examine the feasibility of traditional methods for complex system analysis and design as well as potential novel alternatives in application to transportation systems, identify state-of-the-art models and methods, conduct gap analysis, and thus to lay a foundation for establishing a focused research program in complex systems applied to air transportation.

Alexandrov, Natalia (Editor)

2004-01-01

329

NASA Astrophysics Data System (ADS)

Many quantum systems are being investigated in the hope of building a large-scale quantum computer. All of these systems suffer from decoherence, resulting in errors during the execution of quantum gates. Quantum error correction enables reliable quantum computation given unreliable hardware. Unoptimized topological quantum error correction (TQEC), while still effective, performs very suboptimally, especially at low error rates. Hand optimizing the classical processing associated with a TQEC scheme for a specific system to achieve better error tolerance can be extremely laborious. We describe a tool, Autotune, capable of performing this optimization automatically, and give two highly distinct examples of its use and extreme outperformance of unoptimized TQEC. Autotune is designed to facilitate the precise study of real hardware running TQEC, with every quantum gate having a realistic, physics-based error model.

Fowler, Austin G.; Whiteside, Adam C.; McInnes, Angus L.; Rabbani, Alimohammad

2012-10-01

330

Fullerenes are carbon molecules that form polyhedral cages. Their bond structures are exactly the planar cubic graphs that have only pentagon and hexagon faces. Strikingly, a number of chemical properties of a fullerene can be derived from its graph structure. A rich mathematics of cubic planar graphs and fullerene graphs has grown since they were studied by Goldberg, Coxeter, and others in the early 20th century, and many mathematical properties of fullerenes have found simple and beautiful solutions. Yet many interesting chemical and mathematical problems in the field remain open. In this paper, we present a general overview of recent topological and graph theoretical developments in fullerene research over the past two decades, describing both solved and open problems. WIREs Comput Mol Sci 2015, 5:96–145. doi: 10.1002/wcms.1207 Conflict of interest: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

Schwerdtfeger, Peter; Wirz, Lukas N; Avery, James

2015-01-01

331

Gear tooth topological modification

NASA Technical Reports Server (NTRS)

The topology of parallel axis gears, such as spur and helical gears is modified to produce quieter and more smoothly operating gear sets with more uniform load distribution. A finite element analysis of the gear in its operating mode is made to produce a plot of radial and tangential deflections of the pinion and gear tooth surfaces which will occur when the gears are loaded during operation. The resultant plot is then inverted to produce a plot, or set of coordinates, which will define the path of travel of the gear tooth grinding wheel, which path is a mirror image of the plot of the finite element analysis. The resulting gears, when subjected to operating loads, will thus be deflected tangentially and radially to their optimum operating, or theoretical true involute, positions so as to produce quieter, smoother, and more evenly loaded gear trains.

Kish, Jules G. (Inventor); Isabelle, Charles (Inventor)

1994-01-01

332

333

40 CFR 98.430 - Definition of the source category.

Code of Federal Regulations, 2011 CFR

...Contained in Pre-Charged Equipment or Closed-Cell Foams § 98.430 Definition of the...contained in pre-charged equipment or closed-cell foams, consists of any entity that imports...entity that imports or exports closed-cell foams that contain a fluorinated...

2011-07-01

334

40 CFR 98.430 - Definition of the source category.

Code of Federal Regulations, 2013 CFR

...Contained in Pre-Charged Equipment or Closed-Cell Foams § 98.430 Definition of the...contained in pre-charged equipment or closed-cell foams, consists of any entity that imports...entity that imports or exports closed-cell foams that contain a fluorinated...

2013-07-01

335

Abelian Chern{endash}Simons theory. I. A topological quantum field theory

We give a construction of the Abelian Chern{endash}Simons gauge theory from the point of view of a 2+1-dimensional topological quantum field theory. The definition of the quantum theory relies on geometric quantization ideas that have been previously explored in connection to the non-Abelian Chern{endash}Simons theory [J. Diff. Geom. {bold 33}, 787{endash}902 (1991); Topology {bold 32}, 509{endash}529 (1993)]. We formulate the topological quantum field theory in terms of the category of extended 2- and 3-manifolds introduced in a preprint by Walker in 1991 and prove that it satisfies the axioms of unitary topological quantum field theories formulated by Atiyah [Publ. Math. Inst. Hautes Etudes Sci. Pans {bold 68}, 175{endash}186 (1989)]. {copyright} {ital 1998 American Institute of Physics.}

Manoliu, M. [Department of Mathematics, University of Texas, Austin, Texas 78712 (United States)] [Department of Mathematics, University of Texas, Austin, Texas 78712 (United States)

1998-01-01

336

NSDL National Science Digital Library

In this trick, learners discover how to stick a straw to the palm of their hand, window door, or anywhere using static electricity. This activity introduces learners to negative and positive charges and shows how opposites attract. Note: this trick works best in low humidity (dry air).

Muller, Eric

1995-01-01

337

Quantum Chemical Topology: Knowledgeable atoms in peptides

NASA Astrophysics Data System (ADS)

The need to improve atomistic biomolecular force fields remains acute. Fortunately, the abundance of contemporary computing power enables an overhaul of the architecture of current force fields, which typically base their electrostatics on fixed atomic partial charges. We discuss the principles behind the electrostatics of a more realistic force field under construction, called QCTFF. At the heart of QCTFF lies the so-called topological atom, which is a malleable box, whose shape and electrostatics changes in response to a changing environment. This response is captured by a machine learning method called Kriging. Kriging directly predicts each multipole moment of a given atom (i.e. the output) from the coordinates of the nuclei surrounding this atom (i.e. the input). This procedure yields accurate interatomic electrostatic energies, which form the basis for future-proof progress in force field design.

Popelier, Paul L. A.

2012-06-01

338

Combined topological and landau order from strong correlations in chern bands.

We present a class of states with both topological and conventional Landau order that arise out of strongly interacting spinless fermions in fractionally filled and topologically nontrivial bands with Chern number C=±1. These quantum states show the features of fractional Chern insulators, such as fractional Hall conductivity and interchange of ground-state levels upon insertion of a magnetic flux. In addition, they exhibit charge order and a related additional trivial ground-state degeneracy. Band mixing and geometric frustration of the charge pattern place these lattice states markedly beyond a single-band description. PMID:25479510

Kourtis, Stefanos; Daghofer, Maria

2014-11-21

339

Combined Topological and Landau Order from Strong Correlations in Chern Bands

NASA Astrophysics Data System (ADS)

We present a class of states with both topological and conventional Landau order that arise out of strongly interacting spinless fermions in fractionally filled and topologically nontrivial bands with Chern number C =±1 . These quantum states show the features of fractional Chern insulators, such as fractional Hall conductivity and interchange of ground-state levels upon insertion of a magnetic flux. In addition, they exhibit charge order and a related additional trivial ground-state degeneracy. Band mixing and geometric frustration of the charge pattern place these lattice states markedly beyond a single-band description.

Kourtis, Stefanos; Daghofer, Maria

2014-11-01

340

Loop Variables in Topological Gravity

We examine the relationship between covariant and canonical (Ashtekar/Rovelli/Smolin) loop variables in the context of BF type topological field theories in 2+1 and 3+1 dimensions, with respective gauge groups SO(2,1) and SO(3,1). The latter model can be considered as the simplest topological gravity theory in 3+1 dimensions. We carry out the canonical quantization of this model in both the connection and loop representations, for the two spatial topologies $T^3$ and $S^2\\times S^1$.

Y. Bi; J. Gegenberg

1993-07-22

341

Semilinear (topological) spaces and applications

NASA Technical Reports Server (NTRS)

Semivector spaces are defined and some of their algebraic aspects are developed including some structure theory. These spaces are then topologized to obtain semilinear topological spaces for which a hierarchy of local convexity axioms is identified. A number of fixed point and minmax theorems for spaces with various local convexity properties are established. The spaces of concern arise naturally as various hyperspaces of linear and semilinear (topological) spaces. It is indicated briefly how all this can be applied in socio-economic analysis and optimization.

Prakash, P.; Sertel, M. R.

1971-01-01

342

Discovery of a single topological Dirac fermion in the strong inversion asymmetric compound BiTeCl

NASA Astrophysics Data System (ADS)

In the past few years, a new state of quantum matter known as the time-reversal-invariant topological insulator has been predicted theoretically and realized experimentally. All of the topological insulators discovered so far in experiment are inversion symmetric--except for strained HgTe, which has weak inversion asymmetry, a small bulk gap but no bulk charge polarization. Strong inversion asymmetry in topological insulators would not only lead to many interesting phenomena, such as crystalline-surface-dependent topological electronic states, pyroelectricity and intrinsic topological p-n junctions, but would also serve as an ideal platform for the realization of topological magneto-electric effects, which result from the modification of Maxwell equations in topological insulators. Here we report the discovery of a strong inversion asymmetric topological insulator phase in BiTeCl by angle-resolved photoemission spectroscopy, which reveals Dirac surface states and crystalline-surface-dependent electronic structures. Moreover, we observe a tenfold increase of the bulk energy gap in BiTeCl over the weak inversion asymmetric topological insulator HgTe, making it a promising platform for topological phenomena and possible applications at high temperature.

Chen, Y. L.; Kanou, M.; Liu, Z. K.; Zhang, H. J.; Sobota, J. A.; Leuenberger, D.; Mo, S. K.; Zhou, B.; Yang, S.-L.; Kirchmann, P. S.; Lu, D. H.; Moore, R. G.; Hussain, Z.; Shen, Z. X.; Qi, X. L.; Sasagawa, T.

2013-11-01

343

A Topological Constraint Language with Component Counting

A topological constraint language is a formal language whose variables range over certain subsets of topological spaces, and whose nonlogical primitives are interpreted as topological relations and functions taking these subsets as arguments. Thus, topological constraint languages typically allow us to make assertions such as “region V1 touches the boundary of region V2”, “region V3 is connected” or “region V4

Ian Pratt-hartmann

2002-01-01

344

Topology and survivability of future transport networks

The author discusses the issues surrounding physical and logical transport topology networks, as well as network survivability, and proposes an initial physical topology to support voice, data, and video services. Topology considerations for bursty and nonbursty information transfer are discussed for narrowband and broadband services. Factors influencing the choice of topology are cost, implementation difficulty, planning complexity, operational support, survivability,

J. K. Conlisk

1989-01-01

345

Algebraic & Geometric Topology 9 (2009) 2247Â2309 2247 Tangle analysis of difference topology crystallographic data is combined with the known Tn3 resolvase topological mecha- nisms of binding and strand topological methods for analyzing difference topology experiments involving 3Âstring tangles. Difference

Vazquez, Mariel

346

Fractional electric charge and quark confinement

Owing to their fractional electric charges, quarks are blind to transformations that combine a color center phase with an appropriate electromagnetic one. Such transformations are part of a global $Z_6$-like center symmetry of the Standard Model that is lost when quantum chromodynamics (QCD) is treated as an isolated theory. This symmetry and the corresponding topological defects may be relevant to non-perturbative phenomena such as quark confinement, much like center symmetry and ordinary center vortices are in pure SU($N$) gauge theories. Here we report on our investigations of an analogous symmetry in a 2-color model with dynamical Wilson quarks carrying half-integer electric charge.

Sam R. Edwards; André Sternbeck; Lorenz von Smekal

2012-02-07

347

Semiclassical geometry of charged black holes

At the classical level, two-dimensional dilaton gravity coupled to an abelian gauge field has charged black hole solutions, which have much in common with four-dimensional Reissner-Nordstroem black holes, including multiple asymptotic regions, timelike curvature singularities, and Cauchy horizons. The black hole spacetime is, however, significantly modified by quantum effects, which can be systematically studied in this two-dimensional context. In particular, the back-reaction on the geometry due to pair-creation of charged fermions destabilizes the inner horizon and replaces it with a spacelike curvature singularity. The semiclassical geometry has the same global topology as an electrically neutral black hole.

Frolov, Andrei V.; Kristjansson, Kristjan R.; Thorlacius, Larus [KIPAC/SITP, Stanford University, Stanford, California 94305-4060 (United States); University of Iceland, Science Institute, Dunhaga 3, 107 Reykjavik (Iceland)

2005-07-15

348

Charged Balanced Black Rings in Five Dimensions

We present balanced black ring solutions of pure Einstein-Maxwell theory in five dimensions. The solutions are asymptotically flat, and their tension and gravitational self-attraction are balanced by the repulsion due to rotation and electrical charge. Hence the solutions are free of conical singularities and possess a regular horizon which exhibits the topology S1 x S2 of a torus. We discuss the global charges and the horizon properties of the solutions and show that they satisfy a Smarr relation. We construct these black rings numerically, restricting to the case of black rings with a rotation in the direction of the S1.

Burkhard Kleihaus; Jutta Kunz; Kirsten Schnülle

2010-12-22

349

TRW CHARGED DROPLET SCRUBBER CORROSION STUDIES

The report gives results of corrosion studies to provide definitive data concerning the corrosive nature of coke-oven waste-heat flue gas and its effects on wet electrostatic precipitators, and specifically on TRW's Charged Droplet Scrubber (CDS). The study characterized the chem...

350

NSDL National Science Digital Library

A significant portion of the recent work in the field of physics education research has been concerned with the identification of alternate conceptions (Driver and Easley, 1978) that students have about physical systems. Most of this work has been concentrated in the area of mechanics. There has been some work done in the area of electricity and magnetism but, by comparison, this area has received relatively little attention. The author reports on a study designed to determine if student difficulties in understanding the interactions of electric charges with magnetic fields might be caused, at least in part, by an alternate conception. In discussions among physics teachers one often hears several reasons proposed for these difficulties. One reason given is that magnetic force situations are three dimensional. A second one is that the right hand rule is an unusual procedure which is often misunderstood. These matters are almost certainly involved, but might there not also be some alternate conception causing students difficulty? The purpose of the study was to determine whether the students thought of magnetic poles as exerting forces directly on electric charges, in a manner similar to the behaviour of electrostatic charges.

Maloney, David

2006-05-24

351

Renormalizability of Topologically Massive Gravity

We consider renormalizability of topologically massive gravity in three space-time dimensions. With a usual parametrization of the metric tensor, we establish the statement that topologically massive gravity is in fact renormalizable. In this proof, we make use of not only a recently found, new infrared regularization method of scalar mode but also a covariant ultraviolet regulator with a specific combination of higher derivative terms which is motivated by the new massive gravity in three dimensions.

Ichiro Oda

2009-05-11

352

Refining the shifted topological vertex

We study aspects of the refining and shifting properties of the 3d MacMahon function C{sub 3}(q) used in topological string theory and BKP hierarchy. We derive the explicit expressions of the shifted topological vertex S{sub {lambda}}{sub {mu}}{sub {nu}}(q) and its refined version T{sub {lambda}}{sub {mu}}{sub {nu}}(q,t). These vertices complete results in literature.

Drissi, L. B.; Jehjouh, H.; Saidi, E. H. [Faculte des Sciences, Laboratory/UFR-Physique des Hautes Energies, Rabat, 1014 (Morocco); Groupement National de Physique des Hautes Energies (GNPHE), Siege focal:FS, Rabat, 1014 (Morocco)

2009-01-15

353

Topological approximation of the nonlinear Anderson model.

We study the phenomena of Anderson localization in the presence of nonlinear interaction on a lattice. A class of nonlinear Schrödinger models with arbitrary power nonlinearity is analyzed. We conceive the various regimes of behavior, depending on the topology of resonance overlap in phase space, ranging from a fully developed chaos involving Lévy flights to pseudochaotic dynamics at the onset of delocalization. It is demonstrated that the quadratic nonlinearity plays a dynamically very distinguished role in that it is the only type of power nonlinearity permitting an abrupt localization-delocalization transition with unlimited spreading already at the delocalization border. We describe this localization-delocalization transition as a percolation transition on the infinite Cayley tree (Bethe lattice). It is found in the vicinity of the criticality that the spreading of the wave field is subdiffusive in the limit t?+?. The second moment of the associated probability distribution grows with time as a power law ? t^{?}, with the exponent ?=1/3 exactly. Also we find for superquadratic nonlinearity that the analog pseudochaotic regime at the edge of chaos is self-controlling in that it has feedback on the topology of the structure on which the transport processes concentrate. Then the system automatically (without tuning of parameters) develops its percolation point. We classify this type of behavior in terms of self-organized criticality dynamics in Hilbert space. For subquadratic nonlinearities, the behavior is shown to be sensitive to the details of definition of the nonlinear term. A transport model is proposed based on modified nonlinearity, using the idea of "stripes" propagating the wave process to large distances. Theoretical investigations, presented here, are the basis for consistency analysis of the different localization-delocalization patterns in systems with many coupled degrees of freedom in association with the asymptotic properties of the transport. PMID:25019865

Milovanov, Alexander V; Iomin, Alexander

2014-06-01

354

Quartic quasi-topological gravity, black holes and holography

NASA Astrophysics Data System (ADS)

In this paper, we derive the field equations of quartic quasi-topological gravity by varying the action with respect to the metric. Also, we obtain the linearized graviton equations in the AdS background and find that it is governed by a second-order field equation as in the cases of Einstein, Lovelock or cubic quasi-topological gravities. But in contrast to the cubic quasi-topological gravity, the linearized field equation around a black hole has fourth-order radial derivative of the perturbation. Moreover, we analyze the conditions of having ghost free AdS solutions and AdS planar black holes. In addition, we compute the central charges of the dual conformal field theory of this gravity theory by studying holographic Weyl anomaly. Finally, we consider the effect of quartic term on the causality of dual theory in the tensor channel and show that, in the contrast to the trivial result of cubic quasi-topological gravity, the existence of both cubic and quartic terms leads to a non-trivial constraint. However, this constraint does not imply any lower positive bound on the viscosity/entropy ratio.

Dehghani, M. H.; Vahidinia, M. H.

2013-10-01

355

Topological insulators and Mott physics from the Hubbard interaction

NASA Astrophysics Data System (ADS)

We investigate the Hubbard model on the honeycomb lattice with intrinsic spin-orbit interactions as a paradigm for two-dimensional topological band insulators in the presence of interactions. Applying a combination of Hartree-Fock theory, slave-rotor techniques, and topological arguments, we show that the topological band insulating phase persists up to quite strong interactions. Then we apply the slave-rotor mean-field theory and find a Mott transition at which the charge degrees of freedom become localized on the lattice sites. The spin degrees of freedom, however, are still described by the original Kane-Mele band structure. Gauge-field effects in this region play an important role. When the honeycomb layer is isolated then the spin sector becomes already unstable toward an easy-plane Neel order. In contrast, if the honeycomb lattice is surrounded by extra “screening” layers with gapless spinons, then the system will support a fractionalized topological insulator phase with gapless spinons at the edges. For large interactions, we derive an effective spin Hamiltonian.

Rachel, Stephan; Le Hur, Karyn

2010-08-01

356

String flux mechanism for fractionalization in topologically ordered phases

NASA Astrophysics Data System (ADS)

We construct a family of exactly solvable spin models that illustrate a mechanism for fractionalization in topologically ordered phases, dubbed the string flux mechanism. The essential idea is that an anyon of a topological phase can be endowed with fractional quantum numbers when the string attached to it slides over a background pattern of flux in the ground state. The string flux models that illustrate this mechanism are Zn quantum double models defined on specially constructed d -dimensional lattices, and possess Zn topological order for d ?2 . The models have a unitary, internal symmetry G , where G is an arbitrary finite group. The simplest string flux model is a Z2 toric code defined on a bilayer square lattice, where G =Z2 is layer-exchange symmetry. In general, by varying the pattern of Zn flux in the ground state, any desired fractionalization class [element of H2(G ,Zn) ] can be realized for the Zn charge excitations. While the string flux models are not gauge theories, they map to Zn gauge theories in a certain limit, where they follow a magnetic route for the emergence of low-energy gauge structure. The models are analyzed by studying the action of G symmetry on Zn charge excitations, and by gauging the G symmetry. The latter analysis confirms that distinct fractionalization classes give rise to distinct quantum phases, except that classes [? ] ,[?] -1?H2(G ,Zn) give rise to the same phase. We conclude with a discussion of open issues and future directions.

Hermele, Michael

2014-11-01

357

Area D GEOMETRY AND TOPOLOGY Foundation in Geometry and Topology F4D1

Area D Â GEOMETRY AND TOPOLOGY Foundation in Geometry and Topology F4D1: Â· Topology I (Winter term) Â· Topology II (Summer term) Â· Geometry I (not every year) Â· Geometry II (not every year) Lectures Topology I Â· V4D2 Algebraic Topology II Â· V4D3 Advanced Geometry I Â· V4D4 Advanced Geometry II Advanced

Sturm, Karl-Theodor

358

Topics on topology and superstring theory

In this thesis we discuss some topics about topology and superstring backgrounds with D-branes. We start with a mathematical review about generalized homology and cohomology theories and the Atiyah-Hirzebruch spectral sequence, in order to provide an explicit link between such a spectral sequence and the Gysin map. Then we review the basic facts about line bundles and gerbes with connection. In the second part of the thesis we apply the previous material to study the geometry of type II superstring backgrounds. We first present the cohomological discussion about D-brane charges in analogy with classical electromagnetism, then we use the geometry of gerbes to discuss the nature of the A-field and the B-field as follows from the Freed-Witten anomaly, finally we discuss the K-theoretical approaches to classify D-brane charges. In the last part we discuss some topics about spinors and pinors, with particular attention to non-orientable manifolds.

Fabio Ferrari Ruffino

2009-10-23

359

NASA Astrophysics Data System (ADS)

The mean equililibrium charge of a penetrating ion can be estimated on the basis of Bohr's velocity criterion or Lamb's energy criterion. Qualitative and quantitative results are derived on the basis of the Thomas-Fermi model of the atom, which is discussed explicitly. This includes a brief introduction to the Thomas-Fermi-Dirac model. Special attention is paid to trial function approaches by Lenz and Jensen as well as Brandt and Kitagawa. The chapter also offers a preliminary discussion of the role of the stopping medium, gas-solid differences, and a survey of data compilations.

Sigmund, Peter

360

NSDL National Science Digital Library

This Teaching Resource provides three animated lessons that describe the storage and utilization of energy across plasma membranes. The “Na,K ATPase” animation explains how these pumps establish the electrochemical gradient that stores energy across plasma membranes. The “ATP synthesizing complexes” animation shows how these complexes transfer energy from the inner mitochondrial membrane to adenosine triphosphate (ATP). The “action potential” lesson explains how charged membranes are used to propagate signals along the axons of neurons. These animations serve as valuable resources for any collegiate-level course that describes these important factors. Courses that might employ them include introductory biology, biochemistry, biophysics, cell biology, pharmacology, and physiology.

Jack D. Thatcher (Lewisburg; West Virginia School of Osteopathic Medicine REV)

2013-04-16

361

NSDL National Science Digital Library

Students are introduced to the idea of electrical energy. They learn about the relationships between charge, voltage, current and resistance. They discover that electrical energy is the form of energy that powers most of their household appliances and toys. In the associated activities, students learn how a circuit works and test materials to see if they conduct electricity. Building upon a general understanding of electrical energy, they design their own potato power experiment. In two literacy activities, students learn about the electrical power grid and blackouts.

Integrated Teaching And Learning Program

362

Topological insulators and the QCD vacuum: The theta parameter as a Berry phase

NASA Astrophysics Data System (ADS)

There is considerable evidence, based on large Nc chiral dynamics, holographic QCD, and Monte Carlo studies, that the QCD vacuum is permeated by discrete quasivacua separated by domain walls across which the local value of the topological ? parameter jumps by ±2?. This scenario is realized in a 2D U(1) gauge theory, the CPN -1 sigma model, where a pointlike charge is a domain wall, and ? describes the background electric flux and the polarization of charged pairs in the vacuum. The transition between discrete ? vacua occurs via the transport of integer units of charge between the two spatial boundaries of the domain. We show that this screening process, and the role of ? as an order parameter describing electric polarization, are naturally formulated in terms of Bloch wave eigenstates of the Dirac Hamiltonian in the background gauge field. This formulation is similar to the Berry phase description of electric polarization and quantized charge transport in topological insulators. The Bloch waves are quasiperiodic superpositions of localized Dirac zero modes and the charge transport takes place coherently via topological charge-induced spectral flow. The adiabatic spectral parameter becomes the Bloch wave momentum, which defines a Berry connection around the Brillouin zone of the zero mode band. It describes the local polarization of vacuum pairs, analogous to its role in topological insulator theory. In 4D Yang-Mills theory, the ? domain walls are 2+1-dimensional Chern-Simons membranes, and the ? parameter describes the local polarization of brane-antibrane pairs. The topological description of polarization in 2D U(1) gauge theory generalizes to membrane polarization in 4D QCD by exploiting a relationship between the Berry connection and the gauge cohomology structure encoded in the descent equations of 4D Yang-Mills theory.

Thacker, H. B.

2014-06-01

363

NASA Technical Reports Server (NTRS)

Reliability modeling and parametric yield prediction of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiodes (APDs), which are of interest as an ultra-low noise image capture mechanism for high definition systems, have been investigated. First, the effect of various doping methods on the reliability of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiode (APD) structures fabricated by molecular beam epitaxy is investigated. Reliability is examined by accelerated life tests by monitoring dark current and breakdown voltage. Median device lifetime and the activation energy of the degradation mechanism are computed for undoped, doped-barrier, and doped-well APD structures. Lifetimes for each device structure are examined via a statistically designed experiment. Analysis of variance shows that dark-current is affected primarily by device diameter, temperature and stressing time, and breakdown voltage depends on the diameter, stressing time and APD type. It is concluded that the undoped APD has the highest reliability, followed by the doped well and doped barrier devices, respectively. To determine the source of the degradation mechanism for each device structure, failure analysis using the electron-beam induced current method is performed. This analysis reveals some degree of device degradation caused by ionic impurities in the passivation layer, and energy-dispersive spectrometry subsequently verified the presence of ionic sodium as the primary contaminant. However, since all device structures are similarly passivated, sodium contamination alone does not account for the observed variation between the differently doped APDs. This effect is explained by the dopant migration during stressing, which is verified by free carrier concentration measurements using the capacitance-voltage technique.

Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Yun, Ilgu

1994-01-01

364

Tunable multifunctional topological insulators in ternary Heusler and related compounds

NASA Astrophysics Data System (ADS)

Recently the quantum spin Hall effect was theoretically predicted and experimentally realized in quantum wells based on the binary semiconductor HgTe. The quantum spin Hall state and topological insulators are new states of quantum matter interesting for both fundamental condensed-matter physics and material science. Many Heusler compounds with C1b structure are ternary semiconductors that are structurally and electronically related to the binary semiconductors. The diversity of Heusler materials opens wide possibilities for tuning the bandgap and setting the desired band inversion by choosing compounds with appropriate hybridization strength (by the lattice parameter) and magnitude of spin--orbit coupling (by the atomic charge). Based on first-principle calculations we demonstrate that around 50 Heusler compounds show band inversion similar to that of HgTe. The topological state in these zero-gap semiconductors can be created by applying strain or by designing an appropriate quantumwell structure, similar to the case of HgTe. Many of these ternary zero-gap semiconductors (LnAuPb, LnPdBi, LnPtSb and LnPtBi) contain the rare-earth element Ln, which can realize additional properties ranging from superconductivity (for example LaPtBi) to magnetism (for example GdPtBi) and heavy fermion behaviour (for example YbPtBi). These properties can open new research directions in realizing the quantized anomalous Hall effect and topological superconductors. Heusler compounds are similar to a stuffed diamond, correspondingly, it should be possible to find the "high Z" equivalent of graphene in a graphite-like structure with 18 valence electrons and with inverted bands. Indeed the ternary compounds, such as LiAuSe and KHgSb with a honeycomb structure of their Au-Se and Hg-Sb layers feature band inversion very similar to HgTe which is a strong precondition for existence of the topological surface states. These materials have a gap at the Fermi energy and are therefore candidates for 3D-topological insulators. Additionally they are centro-symmetric, therefore, it is possible to determine the parity of their wave functions, and hence, their topological character. Surprisingly, the compound KHgSb with the strong SOC is topologically trivial, whereas LiAuSe is found to be a topological non-trivial insulator.

Felser, Claudia

2011-03-01

365

Haldane's instanton in 2D Heisenberg model revisited: Along the avenue of topology

NASA Astrophysics Data System (ADS)

Deconfined quantum phase transition from Néel phase to valence bond crystal state in 2D Heisenberg model is under debate nowadays. One crucial issue is the suppression of Haldane's instanton on quantum critical point which drives the spinon deconfined. In this Letter, by making use of the ?-mapping topological current theory, we reexamine the Haldane's instanton in an alternative way along the direction of topology. We find that the monopole events are space-time singularities of Néel field n?, the corresponding topological charges are the wrapping number of n? around the singularities which can be expressed in terms of the Hopf indices and Brouwer degrees of ?-mapping. The suppression of the monopole events can only be guaranteed when the ?-field possesses no zero points. Moreover, the quadrapolarity of monopole events in the Heisenberg model due to the Berry phase is also reproduced in this topological argument.

Jiang, Ying; Yang, Guo-Hong

2009-11-01

366

We show the existence of an isolated soliton excitation over the topological ground-state configuration in chiral helimagnet with the Dzyaloshinskii-Moryia exchange and the strong easy-plane anisotropy. The magnetic field perpendicular to the helical axis stabilizes the kink crystal state which plays a role of ''topological protectorate'' for the traveling soliton with a definite handedness. To find new soliton solution, we use the Baecklund transformation technique. It is pointed out that the traveling soliton carries the magnon density and a magnetic soliton transport may be realized.

Borisov, A. B. [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, Ekaterinburg 620219 (Russian Federation); Kishine, Jun-ichiro [Department of Basic Sciences, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Bostrem, I. G.; Ovchinnikov, A. S. [Department of Physics, Ural State University, Ekaterinburg 620083 (Russian Federation)

2009-04-01

367

Home is an elusive concept. In one manner it is highly specific and individual in its definition, and in other aspects it is ubiquitous, present in our every act. In this thesis I explore several possible definitions of ...

Olgyay, Victor W. (Victor Wayne)

1986-01-01

368

Topological Invariants in Point Group Symmetric Photonic Topological Insulators

We proposed a group-theory method to calculate topological invariant in bi-isotropic photonic crystals invariant under crystallographic point group symmetries. Spin Chern number has been evaluated by the eigenvalues of rotation operators at high symmetry k-points after the pseudo-spin polarized fields are retrieved. Topological characters of photonic edge states and photonic band gaps can be well predicted by total spin Chern number. Nontrivial phase transition is found in large magnetoelectric coupling due to the jump of total spin Chern number. Light transport is also issued at the {\\epsilon}/{\\mu} mismatching boundary between air and the bi-isotropic photonic crystal. This finding presents the relationship between group symmetry and photonic topological systems, which enables the design of photonic nontrivial states in a rational manner.

Chen, Xiao-Dong; Chen, Wen-Jie; Wang, Jia-Rong; Dong, Jian-Wen

2014-01-01

369

Robust transport signatures of topological superconductivity in topological insulator nanowires.

Finding a clear signature of topological superconductivity in transport experiments remains an outstanding challenge. In this work, we propose exploiting the unique properties of three-dimensional topological insulator nanowires to generate a normal-superconductor junction in the single-mode regime where an exactly quantized 2e2/h zero-bias conductance can be observed over a wide range of realistic system parameters. This is achieved by inducing superconductivity in half of the wire, which can be tuned at will from trivial to topological with a parallel magnetic field, while a perpendicular field is used to gap out the normal part, except for two spatially separated chiral channels. The combination of chiral mode transport and perfect Andreev reflection makes the measurement robust to moderate disorder, and the quantization of conductance survives to much higher temperatures than in tunnel junction experiments. Our proposal may be understood as a variant of a Majorana interferometer which is easily realizable in experiments. PMID:25238379

de Juan, Fernando; Ilan, Roni; Bardarson, Jens H

2014-09-01

370

This paper elaborates on the components of a working definition of developmental dyslexia. It follows the general format of\\u000a a paper by Lyon published in Annals of Dyslexia in 1995, which elaborated on a working definition proposed in 1994 (Lyon,\\u000a 1995). The current definition agreed on by the work group updates and expands on the working definition from 1994.

G. Reid Lyon; Sally E. Shaywitz; Bennett A. Shaywitz

2003-01-01

371

Quantized anomalous Hall effect in magnetic topological insulators.

The anomalous Hall effect is a fundamental transport process in solids arising from the spin-orbit coupling. In a quantum anomalous Hall insulator, spontaneous magnetic moments and spin-orbit coupling combine to give rise to a topologically nontrivial electronic structure, leading to the quantized Hall effect without an external magnetic field. Based on first-principles calculations, we predict that the tetradymite semiconductors Bi2Te3, Bi2Se3, and Sb2Te3 form magnetically ordered insulators when doped with transition metal elements (Cr or Fe), in contrast to conventional dilute magnetic semiconductors where free carriers are necessary to mediate the magnetic coupling. In two-dimensional thin films, this magnetic order gives rise to a topological electronic structure characterized by a finite Chern number, with the Hall conductance quantized in units of e2/h (where e is the charge of an electron and h is Planck's constant). PMID:20522741

Yu, Rui; Zhang, Wei; Zhang, Hai-Jun; Zhang, Shou-Cheng; Dai, Xi; Fang, Zhong

2010-07-01

372

Generalized Ablowitz-Ladik hierarchy in topological string theory

This paper addresses the issue of integrable structures in topological string theory on generalized conifolds. Open string amplitudes of this theory can be expressed as the matrix elements of an operator on the Fock space of 2D charged free fermion fields. The generating function of these amplitudes with respect to the product of two independent Schur functions becomes a tau function of the 2D Toda hierarchy. The associated Lax operators turn out to have a particular factorized form. This factorized form of the Lax operators characterizes a generalization of the Ablowitz-Ladik hierarchy embedded in the 2D Toda hierarchy. The generalized Ablowitz-Ladik hierarchy is thus identified as a fundamental integrable structure of topological string theory on the generalized conifolds.

Kanehisa Takasaki

2013-12-27

373

Induced fractional valley number in graphene with topological defects

NASA Astrophysics Data System (ADS)

We report on the possibility of valley number fractionalization in graphene with a topological defect that is accounted for in the Dirac equation by a pseudomagnetic field. The valley number fractionalization is attributable to an imbalance in the number of one-particle states in one of the two Dirac points with respect to the other. The difference in the number of one-particle states is manifest and can be exactly evaluated thanks to an external uniform magnetic field. Although the external magnetic field is precluded, the net valley number results in being dependent only on the flux of the pseudomagnetic field. We also discuss the analogous effect that the topological defect might lead to the induced spin polarization of the charge carriers in graphene.

Obispo, Angel E.; Hott, Marcelo

2015-01-01

374

Superconductivity in the topological semimetal YPtBi

NASA Astrophysics Data System (ADS)

The noncentrosymmetric half Heusler compound YPtBi exhibits superconductivity below a critical temperature Tc=0.77 K with a zero-temperature upper critical field Hc2(0)=1.5 T. Magnetoresistance and Hall measurements support theoretical predictions that this material is a topologically nontrivial semimetal having a surprisingly low positive charge-carrier density of 2×1018 cm-3. Unconventional linear magnetoresistance and beating in Shubnikov-de Haas oscillations point to spin-orbit split Fermi surfaces. The sensitivity of magnetoresistance to surface roughness suggests a possible contribution from surface states. The combination of noncentrosymmetry and strong spin-orbit coupling in YPtBi presents a promising platform for the investigation of topological superconductivity.

Butch, N. P.; Syers, P.; Kirshenbaum, K.; Hope, A. P.; Paglione, J.

2011-12-01

375

Topological fluctuations in dense matter with two colors

NASA Astrophysics Data System (ADS)

We study the topological charge fluctuations of an SU(2) lattice gauge theory containing both Nf=2 and 4 flavors of Wilson fermion, at low temperature with non-zero chemical potential ?. The topological susceptibility, ?T, is used to characterise differing physical regimes as ? is varied between the onset of matter at ?o and color deconfinement at ?d. Suppression of instantons by matter via Debye screening is also investigated, revealing effects not captured by perturbative predictions. In particular, the breaking of scale invariance leads to the mean instanton size ?bar becoming ?-dependent in the regime between onset and deconfinement, with a scaling ?bar?? over the range ?o

Hands, Simon; Kenny, Philip

2011-07-01

376

Symmetry-protected topological (SPT) phases in gapped electronic systems can host robust surface states that remain gapless as long as the relevant global symmetry remains unbroken. The nature of the charge carriers in SPT surface states is intimately tied to the symmetry of the bulk, resulting in one

McQuade, D. Tyler

377

Boundary conditions for spacelike and timelike warped AdS3 spaces in topologically massive gravity

We propose a set of consistent boundary conditions containing the spacelike warped black holes solutions of Topologically Massive Gravity. We prove that the corresponding asymptotic charges whose algebra consists in a Virasoro algebra and a current algebra are finite, integrable and conserved. A similar analysis is performed for the timelike warped AdS3 spaces which contain a family of regular solitons.

Geoffrey Compère; Stéphane Detournay

2009-01-01

378

Topological Strings from Quantum Mechanics

We propose a general correspondence which associates a non-perturbative quantum-mechanical operator to a toric Calabi-Yau manifold, and we conjecture an explicit formula for its spectral determinant in terms of an M-theoretic version of the topological string free energy. As a consequence, we derive an exact quantization condition for the operator spectrum, in terms of the vanishing of a generalized theta function. The perturbative part of this quantization condition is given by the Nekrasov-Shatashvili limit of the refined topological string, but there are non-perturbative corrections determined by the conventional topological string. We analyze in detail the cases of local P2, local P1xP1 and local F1. In all these cases, the predictions for the spectrum agree with the existing numerical results. We also show explicitly that our conjectured spectral determinant leads to the correct spectral traces of the corresponding operators, which are closely related to topological string theory at orbifold points. Physically, our results provide a Fermi gas picture of topological strings on toric Calabi-Yau manifolds, which is fully non-perturbative and background independent. They also suggest the existence of an underlying theory of M2 branes behind this formulation. Mathematically, our results lead to precise, surprising conjectures relating the spectral theory of functional difference operators to enumerative geometry.

Alba Grassi; Yasuyuki Hatsuda; Marcos Marino

2014-11-27

379

Topological Insulators at Room Temperature

Topological insulators are new states of quantum matter with surface states protected by the time-reversal symmetry. In this work, we perform first-principle electronic structure calculations for Sb{sub 2}Te{sub 3}, Sb{sub 2}Se{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} crystals. Our calculations predict that Sb{sub 2}Te{sub 3}, Bi{sub 2}T e{sub 3} and Bi{sub 2}Se{sub 3} are topological insulators, while Sb{sub 2}Se{sub 3} is not. In particular, Bi{sub 2}Se{sub 3} has a topologically non-trivial energy gap of 0.3eV , suitable for room temperature applications. We present a simple and unified continuum model which captures the salient topological features of this class of materials. These topological insulators have robust surface states consisting of a single Dirac cone at the {Lambda} point.

Zhang, Haijun; /Beijing, Inst. Phys.; Liu, Chao-Xing; /Tsinghua U., Beijing; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Dai, Xi; Fang, Zhong; /Beijing, Inst. Phys.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-03-25

380

In the past few years, we have presented a new way of considering quark confinement. Through a careful choice of a Cho-Duan-Ge Abelian Decomposition, we can construct the QCD Wilson Loop in terms of an Abelian restricted field. The relationship between the QCD and restricted string tensions is exact; and we do not need to gauge fix, apply any path ordering of gauge links, or additional path integrals. This hints at why mesons are colour neutral. Furthermore, the Abelian restricted field contains two parts: a Maxwell term, and a topological term. The topological term can describe magnetic monopoles and other topological objects, which can be studied both numerically and theoretically. By examining the topological part of the restricted field strength we have found evidence suggesting that these objects, which will contribute to confinement if present, are indeed there. Previous studies have used simplifications, breaking the exact relationship between the restricted and QCD string tensions, but it was found that the topological term dominated the restricted string tension. Here we remove those simplifications, and show that the Abelian restricted field does indeed fully explain confinement. However, our results for how much of the restricted string tension arises from the topological objects show strong dependence on the lattice spacing and level of smearing, so we are not yet able to draw a definitive conclusion.

Nigel Cundy; Yongmin Cho; Weonjong Lee

2014-11-04

381

Quark masses, the Dashen phase, and gauge field topology

The CP violating Dashen phase in QCD is predicted by chiral perturbation theory to occur when the up–down quark mass difference becomes sufficiently large at fixed down-quark mass. Before reaching this phase, all physical hadronic masses and scattering amplitudes are expected to behave smoothly with the up-quark mass, even as this mass passes through zero. In Euclidean space, the topological susceptibility of the gauge fields is positive at positive quark masses but diverges to negative infinity as the Dashen phase is approached. A zero in this susceptibility provides a tentative signal for the point where the mass of the up quark vanishes. I discuss potential ambiguities with this determination. -- Highlights: •The CP violating Dashen phase in QCD occurs when the up quark mass becomes sufficiently negative. •Before reaching this phase, all physical hadronic masses and scattering amplitudes behave smoothly with the up-quark mass. •The topological susceptibility of the gauge fields diverges to negative infinity as the Dashen phase is approached. •A zero in the topological susceptibility provides a tentative signal for the point where the mass of the up quark vanishes. •The universality of this definition remains unproven. Potential ambiguities are discussed.

Creutz, Michael, E-mail: creutz@bnl.gov

2013-12-15

382

Nearly flatbands with nontrivial topology.

We report the theoretical discovery of a class of 2D tight-binding models containing nearly flatbands with nonzero Chern numbers. In contrast with previous studies, where nonlocal hoppings are usually required, the Hamiltonians of our models only require short-range hopping and have the potential to be realized in cold atomic gases. Because of the similarity with 2D continuum Landau levels, these topologically nontrivial nearly flatbands may lead to the realization of fractional anomalous quantum Hall states and fractional topological insulators in real materials. Among the models we discover, the most interesting and practical one is a square-lattice three-band model which has only nearest-neighbor hopping. To understand better the physics underlying the topological flatband aspects, we also present the studies of a minimal two-band model on the checkerboard lattice. PMID:21770533

Sun, Kai; Gu, Zhengcheng; Katsura, Hosho; Das Sarma, S

2011-06-10

383

Ring polymers with topological constraints

In the first part of this work a summary is provided of some recent experiments and theoretical results which are relevant in the research of systems of polymer rings in nontrivial topological conformations. Next, some advances in modeling the behavior of single polymer knots are presented. The numerical simulations are performed with the help of the Wang-Landau Monte Carlo algorithm. To sample the polymer conformation a set of random transformations called pivot moves is used. The crucial problem of preserving the topology of the knots after each move is tackled with the help of two new techniques which are briefly explained. As an application, the results of an investigation of the effects of topology on the thermal properties of polymer knots is reported. In the end, original results are discussed concerning the use of parallelized codes to study polymers knots composed by a large number of segments within the Wang-Landau approach.

Yani Zhao; Franco Ferrari

2014-02-02

384

Quantum Capacitance in Topological Insulators

Topological insulators show unique properties resulting from massless, Dirac-like surface states that are protected by time-reversal symmetry. Theory predicts that the surface states exhibit a quantum spin Hall effect with counter-propagating electrons carrying opposite spins in the absence of an external magnetic field. However, to date, the revelation of these states through conventional transport measurements remains a significant challenge owing to the predominance of bulk carriers. Here, we report on an experimental observation of Shubnikov-de Haas oscillations in quantum capacitance measurements, which originate from topological helical states. Unlike the traditional transport approach, the quantum capacitance measurements are remarkably alleviated from bulk interference at high excitation frequencies, thus enabling a distinction between the surface and bulk. We also demonstrate easy access to the surface states at relatively high temperatures up to 60?K. Our approach may eventually facilitate an exciting exploration of exotic topological properties at room temperature. PMID:22993694

Xiu, Faxian; Meyer, Nicholas; Kou, Xufeng; He, Liang; Lang, Murong; Wang, Yong; Yu, Xinxin; Fedorov, Alexei V.; Zou, Jin; Wang, Kang L.

2012-01-01

385

Topological exploration of subterranean environments

The need for reliable maps of subterranean spaces too hazardous for humans to occupy has motivated the development of robotic mapping tools suited to these domains. As such, this work describes a system developed for autonomous topological exploration of mine environments to facilitate the process of mapping. The exploration framework is based upon the interaction of three main components: Node detection, node matching, and edge exploration. Node detection robustly identifies mine corridor intersections from sensor data and uses these features as the building blocks of a topological map. Node matching compares newly observed intersections to those stored in the map, providing global localization during exploration. Edge exploration translates topological exploration objectives into locomotion along mine corridors. This article describes both the robotic platform and the algorithms developed for exploration, and presents results from experiments conducted at a research coal mine near Pittsburgh, PA.

Silver, D.; Ferguson, D.; Morris, A.; Thayer, S. [Carnegie Mellon University, Pittsburgh, PA (United States)

2006-06-15

386

Topological gravity and transgression holography

We show that Poincare-invariant topological gravity in even dimensions can be formulated as a transgression field theory in one higher dimension whose gauge connections are associated to linear and nonlinear realizations of the Poincare group ISO(d-1,1). The resulting theory is a gauged WZW model whereby the transition functions relating gauge fields live in the coset ISO(d-1,1)/SO(d-1,1). The coordinate parametrizing the coset space is identified with the scalar field in the adjoint representation of the gauge group of the even-dimensional topological gravity theory. The supersymmetric extension leads to topological supergravity in two dimensions starting from a transgression field theory which is invariant under the supersymmetric extension of the Poincare group in three dimensions. We also apply this construction to a three-dimensional Chern-Simons theory of gravity which is invariant under the Maxwell algebra and obtain the corresponding WZW model.

Patricio Salgado; Richard J. Szabo; Omar Valdivia

2014-01-15

387

Search for Gauge-Mediated SUSY Breaking Topologies at $\\\\sqrt{s}\\\\sim{189}$ GeV

Searches for topologies characteristic of Gauge Mediated SUSY Breaking models (GMSB) are performed by analysing 173.6 pb^-1 of data collected at Ecm = 188.6~GeV with the ALEPH detector.These topologies include acoplanar photons, non-pointing single photon, acoplanar leptons, large impact parameter leptons, detached slepton decay vertices, heavy stable charged sleptons and four leptons plus missing energy final states.No evidence for these

R Barate; D Décamp; P Ghez; C Goy; S Jézéquel; J P Lees; F Martin; E Merle; M N Minard; B Pietrzyk; R Alemany; S Bravo; M P Casado; M Chmeissani; J M Crespo; E Fernández; M Fernández-Bosman; L Garrido; E Graugès-Pous; A Juste; M Martínez; G Merino; R Miquel; L M Mir; P Morawitz; A Pacheco; I Riu; H Ruiz; A Colaleo; D Creanza; M De Palma; Giuseppe Iaselli; G Maggi; M Maggi; S Nuzzo; A Ranieri; G Raso; F Ruggieri; G Selvaggi; L Silvestris; P Tempesta; A Tricomi; G Zito; X Huang; J Lin; Q Ouyang; T Wang; Y Xie; R Xu; S Xue; J Zhang; L Zhang; W Zhao; D Abbaneo; G Boix; O L Buchmüller; M Cattaneo; F Cerutti; V Ciulli; G Davies; G Dissertori; H Drevermann; Roger W Forty; M Frank; F Gianotti; T C Greening; A W Halley; J B Hansen; J Harvey; P Janot; B Jost; M Kado; O Leroy; P Maley; P Mato; Adolf G Minten; A Moutoussi; F Ranjard; Luigi Rolandi; W D Schlatter; M Schmitt; O Schneider; P Spagnolo; W Tejessy; F Teubert; E Tournefier; Andrea Valassi; A E Wright; Ziad J Ajaltouni; F Badaud; G Chazelle; O Deschamps; S Dessagne; A Falvard; C Ferdi; P Gay; C Guicheney; P Henrard; J Jousset; B Michel; S Monteil; J C Montret; D Pallin; J M Pascolo; P Perret; F Podlyski; J D Hansen; J R Hansen; P H Hansen; B S Nilsson; B Rensch; A Wäänänen; G Daskalakis; A Kyriakis; C Markou; Errietta Simopoulou; Anna Vayaki; A Blondel; J C Brient; F P Machefert; A Rougé; M Swynghedauw; R Tanaka; H L Videau; E Focardi; G Parrini; K Zachariadou; M Corden; C H Georgiopoulos; A Antonelli; G Bencivenni; G Bologna; F Bossi; P Campana; G Capon; V Chiarella; P Laurelli; G Mannocchi; F Murtas; G P Murtas; L Passalacqua; M Pepé-Altarelli; M Chalmers; J Kennedy; J G Lynch; P Negus; V O'Shea; B Räven; D Smith; P Teixeira-Dias; A S Thompson; J J Ward; R J Cavanaugh; S Dhamotharan; C Geweniger; P Hanke; V Hepp; E E Kluge; G Leibenguth; A Putzer; K Tittel; S Werner; M Wunsch; R Beuselinck; David M Binnie; W Cameron; Peter J Dornan; M Girone; S M Goodsir; N Marinelli; E B Martin; J Nash; J Nowell; H Przysiezniak; A Sciabà; J K Sedgbeer; J C Thompson; E Thomson; M D Williams; V M Ghete; P Girtler; E Kneringer; D Kuhn; G Rudolph; C K Bowdery; P G Buck; G Ellis; A J Finch; F Foster; G Hughes; R W L Jones; N A Robertson; M Smizanska; M I Williams; I Giehl; F Hölldorfer; K Jakobs; K Kleinknecht; M Kröcker; A S Müller; H A Nürnberger; G Quast; B Renk; E Rohne; H G Sander; S Schmeling; H W Wachsmuth; C Zeitnitz; T Ziegler; A Bonissent; J Carr; P Coyle; A Ealet; D Fouchez; A Tilquin; M Aleppo; M Antonelli; S S Gilardoni; F Ragusa; V Büscher; H Dietl; G Ganis; K Hüttmann; G Lütjens; C Mannert; W Männer; H G Moser; S Schael; Ronald Settles; H C J Seywerd; H Stenzel; W Wiedenmann; G Wolf; P Azzurri; J Boucrot; O Callot; S Chen; M Davier; L Duflot; J F Grivaz; P Heusse; A Jacholkowska; J Lefrançois; L Serin; J J Veillet; I Videau; J B De Vivie de Régie; D Zerwas; G Bagliesi; T Boccali; C Bozzi; G Calderini; R Dell'Orso; I Ferrante; A Giassi; A Gregorio; F Ligabue; P S Marrocchesi; A Messineo; Fabrizio Palla; G Rizzo; G Sanguinetti; G Sguazzoni; Roberto Tenchini; A Venturi; P G Verdini; G A Blair; J Coles; G D Cowan; M G Green; D E Hutchcroft; L T Jones; T Medcalf; J A Strong; David R Botterill; R W Clifft; T R Edgecock; P R Norton; I R Tomalin; B Bloch-Devaux; P Colas; B Fabbro; G Faïf; E Lançon; M C Lemaire; E Locci; P Pérez; J Rander; J F Renardy; A Rosowsky; P Seager; A Trabelsi; B Tuchming; B Vallage; S N Black; J H Dann; C Loomis; H Y Kim; N P Konstantinidis; A M Litke; M A McNeil; G Taylor; C N Booth; S L Cartwright; F Combley; P N Hodgson; M H Lehto; L F Thompson; K Affholderbach; A Böhrer; S Brandt; Claus Grupen; J Hess; A Misiejuk; G Prange; U Sieler; C Borean; G Giannini; B Gobbo; J Pütz; J E Rothberg; S R Wasserbaech; R W Williams; S R Armstrong; P Elmer; D P S Ferguson; Y Gao; S González; O J Hayes; H Hu; S Jin; J Kile; P A McNamara; J Nielsen; W Orejudos; Y B Pan; Y Saadi; I J Scott; J Walsh; J H Von Wimmersperg-Töller; Wu Sau Lan; X Wu; G Zobernig

1999-01-01

388

A Low-power Area-efficient Switching Scheme for Charge-sharing DACs in SAR ADCs

Analysis and experimental results for a new switching scheme and topology for charge sharing DACs used in successive approximation register (SAR) ADCs is presented. The characteristics of the SAR algorithm are exploited ...

Chen, Fred Fu-Chin

389

Topological Constraints on Magnetic Relaxation

The final state of turbulent magnetic relaxation in a reversed field pinch is well explained by Taylor's hypothesis. However, recent resistive-magnetohydrodynamic simulations of the relaxation of braided solar coronal loops have led to relaxed fields far from the Taylor state, despite the conservation of helicity. We point out the existence of an additional topological invariant in any flux tube with a nonzero field: the topological degree of the field line mapping. We conjecture that this constrains the relaxation, explaining why only one of three example simulations reaches the Taylor state.

Yeates, A. R.; Hornig, G.; Wilmot-Smith, A. L. [Division of Mathematics, University of Dundee, Dundee, DD1 4HN (United Kingdom)

2010-08-20

390

Topological Constraints on Magnetic Relaxation

The final state of turbulent magnetic relaxation in a reversed field pinch is well explained by Taylor's hypothesis. However, recent resistive-magnetohydrodynamic simulations of the relaxation of braided solar coronal loops have led to relaxed fields far from the Taylor state, despite the conservation of helicity. We point out the existence of an additional topological invariant in any flux tube with non-zero field: the topological degree of the field line mapping. We conjecture that this constrains the relaxation, explaining why only one of three example simulations reaches the Taylor state.

A. R. Yeates; G. Hornig; A. L. Wilmot-Smith

2010-07-28

391

Topology and Fragility in Cosmology

We introduce the notion of topological fragility and briefly discuss some examples from the literature. An important example of this type of fragility is the way globally anisotropic Bianchi V generalisations of the FLRW $k=-1$ model result in a radical restriction on the allowed topology of spatial sections, thereby excluding compact cosmological models with negatively curved three-sections with anisotropy. An outcome of this is to exclude chaotic mixing in such models, which may be relevant, given the many recent attempts at employing compact FLRW $k=-1$ models to produce chaotic mixing in the cosmic microwave background radiation, if the Universe turns out to be globally anisotropic.

M. J. Reboucas; R. K. Tavakol; A. F. F. Teixeira

1997-11-06

392

Detecting topological currents in graphene superlattices

Topological materials may exhibit Hall-like currents flowing transversely to the applied electric field even in the absence of a magnetic field. In graphene superlattices, which have broken inversion symmetry, topological ...

Gorbachev, R. V.

393

Substructure Topology Preserving Simplification of Tetrahedral Meshes

the power of our system with real world scientific datasets from electromagnetism simulations. 1. Our system combines this topological validity test with simple geometric and numeric error measuresSubstructure Topology Preserving Simplification of Tetrahedral Meshes Fabien Vivodtzev1, Georges

Boyer, Edmond

394

Topology of Musical Techniques for discovering topological structures in large data sets are now

Topology of Musical Data Techniques for discovering topological structures in large data sets in which to expect to find nontrivial topological features. The analysis is able to recover three important;Topological Surfaces Defined by Data The Betti numbers of a cloud of points depends on scale. For small, all

Sethares, William A.

395

Quantized gravitomagnetic charges from WIMT: cosmological consequences

Using the formalism of Weitzenb\\"ock Induced Matter Theory (WIMT) we calculate the gravito-magnetic charge on a topological string which is induced through a foliation on a 5D gravito-electromagnetic vacuum defined on a 5D Ricci-flat metric, which produces a symmetry breaking on an axis. We obtain the resonant result that the quantized charges are induced on the effective 4D hypersurface. This quantization describes the behavior of a test gravito-electric charge in the vicinity of a point gravito-magnetic monopole, both geometrically induced from a 5D vacuum. We demonstrate how gravito-magnetic monopoles would decrease exponentially during the inflationary expansion of the universe.

Jesús Martín Romero; Mauricio Bellini

2014-09-11

396

Topological Properties of Spatial Coherence Function

NASA Astrophysics Data System (ADS)

The topological properties of the spatial coherence function are investigated rigorously. The phase singular structures (coherence vortices) of coherence function can be naturally deduced from the topological current, which is an abstract mathematical object studied previously. We find that coherence vortices are characterized by the Hopf index and Brouwer degree in topology. The coherence flux quantization and the linking of the closed coherence vortices are also studied from the topological properties of the spatial coherence function.

Ren, Ji-Rong; Zhu, Tao; Duan, Yi-Shi

2008-02-01

397

Formation of a topological non-Fermi liquid in MnSi.

Fermi liquid theory provides a remarkably powerful framework for the description of the conduction electrons in metals and their ordering phenomena, such as superconductivity, ferromagnetism, and spin- and charge-density-wave order. A different class of ordering phenomena of great interest concerns spin configurations that are topologically protected, that is, their topology can be destroyed only by forcing the average magnetization locally to zero. Examples of such configurations are hedgehogs (points at which all spins are either pointing inwards or outwards) and vortices. A central question concerns the nature of the metallic state in the presence of such topologically distinct spin textures. Here we report a high-pressure study of the metallic state at the border of the skyrmion lattice in MnSi, which represents a new form of magnetic order composed of topologically non-trivial vortices. When long-range magnetic order is suppressed under pressure, the key characteristic of the skyrmion lattice--that is, the topological Hall signal due to the emergent magnetic flux associated with the topological winding--is unaffected in sign or magnitude and becomes an important characteristic of the metallic state. The regime of the topological Hall signal in temperature, pressure and magnetic field coincides thereby with the exceptionally extended regime of a pronounced non-Fermi-liquid resistivity. The observation of this topological Hall signal in the regime of the NFL resistivity suggests empirically that spin correlations with non-trivial topological character may drive a breakdown of Fermi liquid theory in pure metals. PMID:23636328

Ritz, R; Halder, M; Wagner, M; Franz, C; Bauer, A; Pfleiderer, C

2013-05-01

398

Ch 16 Electric Charge &Ch 16. Electric Charge & Electric Field

Ch 16 Electric Charge &Ch 16. Electric Charge & Electric Field Liu UCD Phy1B 2012 #12;I Basic ConceptsI. Basic Concepts Static electricity: charges at rest Electric charge Like charges repel Unlike charges attract Liu UCD Phy1B 2012 #12;Electric ChargeElectric Charge Electron charge: -eElectron charge

Yoo, S. J. Ben

399

Magnetotransport in Thin Films and Heterostructures of Topological Matter

NASA Astrophysics Data System (ADS)

Topological insulators are semiconducting materials that host spin-momentum locked surface Dirac Fermions. These massless surface states occur as a result of a symmetry-protected band crossing. The effective mass of surface electrons can be tuned by breaking that symmetry. Such materials are thus attractive for technological applications as they allow one to manipulate the charge, spin and effective mass of electrons in devices. The surface states are, however, difficult to access and manipulate using conventional electrical probes, as the underlying bulk is not usually insulating. In this thesis, we have studied electrical transport in two prototypical topological systems, Bi2Te2Se---belonging to the class of Z2 topological insulators, and SnTe---a topological crystalline insulator. We also looked at how the breaking of crystalline symmetry by proximity to a ferromagnet alters the transport in SnTe. We grew Bi2Te2Se thin films by molecular beam epitaxy (MBE) on Si(111) and studied the magnetoresistance (MR), which was found to exhibit weak antilocalization (WAL) at low fields and linear MR at high fields. By proposing a model that accounts for both WAL and the linear MR simultaneously, we were able to separate the MR contribution of topological surface-states from that of Rashba spin-orbit split bulk states. In SnTe thin films, also grown by MBE on BaF2(001) and Si(001), we demonstrated that film crystallinity, morphology, carrier density and mobility all improve with increasing growth temperature. By studying WAL in different films, it was found that valley coupling reduced the measured number of WAL channels. This is a direct consequence of the degenerate surface bands of SnTe. Changes in the shape of the bulk Fermi surface were also seen to influence the measured number of WAL channels. Proximity-induced magnetism was observed in a SnTe-EuS heterostructure though the anomalous Hall effect. The observation of an isotropic hysteretic MR was shown to be evidence of domain-wall-supported, one-dimensional conduction as previously hypothesized for Bi2Se3-EuS. As we enter the exciting era of topological condensed matter physics, these results will be important to the development of future device ideas relying on the manipulation of topological surface states.

Assaf, Badih Assaf

400

Canonical structure of topologically massive gravity with a cosmological constant

We study the canonical structure of three-dimensional topologically massive gravity with a cosmological constant, using the full power of Dirac's method for constrained Hamiltonian systems. It is found that the dimension of the physical phase space is two per spacetime point, which corresponds to a single Lagrangian degree of freedom. The analysis of the AdS asymptotic region reveals a remarkable relation to 3D gravity with torsion: in the limit of vanishing torsion, the conserved charges and asymptotic symmetries of the two theories become identical.

M. Blagojevi?; B. Cvetkovi?

2008-12-27

401

The Constraint Algebra of Topologically Massive AdS Gravity

Three-dimensional topologically massive AdS gravity has a complicated constraint algebra, making it difficult to count nonperturbative degrees of freedom. I show that a new choice of variables greatly simplifies this algebra, and confirm that the theory contains a single propagating mode for all values of the mass parameter and the cosmological constant. As an added benefit, I rederive the central charges and conformal weights of the boundary conformal field theory from an explicit analysis of the asymptotic algebra of constraints.

S. Carlip

2008-07-25

402

Topological self-dual vacua of deformed gauge theories

NASA Astrophysics Data System (ADS)

We propose a deformation principle of gauge theories in three dimensions that can describe topologically stable self-dual gauge fields, i.e., vacua configurations that in spite of their masses do not deform the background geometry and are locally undetected by charged particles. We interpret these systems as describing boundary degrees of freedom of a self-dual Yang-Mills field in 2 + 2 dimensions with mixed boundary conditions. Some of these fields correspond to Abrikosov-like vortices with an exponential damping in the direction penetrating into the bulk. We also propose generalizations of these ideas to higher dimensions and arbitrary p-form gauge connections.

Oliva, Julio; Valenzuela, Mauricio

2014-09-01

403

Topological phase shift in a cold-atom interferometer

NASA Astrophysics Data System (ADS)

Matter-wave interferences in a four-pulse version of a Ramsey-Bordé atom interferometer have been utilized to study phase shifts. A topological phase shift analogous to the scalar Aharonov-Bohm effect proposed for charged-particle interferences in the presence of a pulsed electrostatic potential has been investigated. The time-dependent potential has been generated by the interaction of a laser field with an induced atomic dipole without spatial variation along the interferometer arms. The atom interferometer has been run with laser-cooled magnesium atoms stored in a magneto-optical trap.

Müller, J. H.; Bettermann, D.; Rieger, V.; Sengstock, K.; Sterr, U.; Ertmer, W.

1995-02-01

404

Results on fuzzy soft topological spaces

B. Tanay et. al. introduced and studied fuzzy soft topological spaces. Here we introduce fuzzy soft point and study the concept of neighborhood of a fuzzy soft point in a fuzzy soft topological space. We also study fuzzy soft closure and fuzzy soft interior. Separation axioms and connectedness are introduced and investigated for fuzzy soft topological spaces.

J. Mahanta; P. K. Das

2012-03-03

405

Topological constraints in nucleic acid hybridization kinetics

Topological constraints in nucleic acid hybridization kinetics Justin S. Bois, Suvir Venkataraman1 that the topological constraint of zero linking number between the loops effectively prevents conversion to the minimum constraints that govern the metastability of kissing complementary loops. This topological viewpoint suggests

Straight, Aaron

406

A Topological Constraint Language with Component Counting

A Topological Constraint Language with Component Counting Ian Pratt-Hartmann Department of Computer Science, University of Manchester, U.K. ipratt@cs.man.ac.uk ABSTRACT. A topological constraint language, topological constraint languages typically allow us to make assertions such as "region Â¢Â¡ touches

Pratt-Hartmann, Ian

407

Topological constraints on basic PWM converters

A modeling and synthesis technique is introduced for single-ended, ladder-structured, DC-DC converter topologies. Topological constraints are derived that enhance the understanding of structural properties of converter circuits and clarify the roles of inductors and capacitors in various converters using magnetic or capacitive energy storage\\/transfer mechanism. The exact duality relationships among the basic converter topologies are established.

Kwang-Hwa Liu; F. C. Lee

1988-01-01

408

Graph Embedding with Topological CycleConstraints ?

Graph Embedding with Topological CycleÂConstraints ? Christoph Dornheim Institut fÂ¨ur Informatik of vertices. However, topologiÂ cal constraints that are less specific than geometric constraints have gained to place the vertices. In this paper we consider a special sort of topological constraints which we call

Nebel, Bernhard

409

Topological Hierarchy for Functions on Triangulated Surfaces

driven by approximation error. B. Related work The topological analysis of scalar valued scientific data this data structure to ex- tract topologically valid approximations that satisfy error bounds provided, multi-resolution data structure. I. INTRODUCTION THE efficient construction of topologically and ge

Edelsbrunner, Herbert

410

Spherical Topological Relations Max J. Egenhofer

. The analysis of the algebraic compositions of spherical topological relations indicates that spherical and Spherical Topological Relations Max J. Egenhofer Journal on Data Semantics, Vol. 2, 2005 (in press). #12Spherical Topological Relations Max J. Egenhofer National Center for Geographic Information

Egenhofer, Max J.

411

Motivation Applications Theorems Noise Detecting Topological Structure

Bradley. Topology and intelligent data analysis. Intelligent Data Analysis. Volume 8, 2004. 505Â515. Here in an -neighborhood of a data set while varying , and then use that information to deduce the topological propertiesMotivation Applications Theorems Noise Detecting Topological Structure Shmuel Weinberger University

McReynolds, Ben

412

Formal Topology and Search Engine Silvio Valentini

Formal Topology and Search Engine Silvio Valentini Dipartimento di Matematica Pura ed Applicata, 2001 Abstract Formal topology can be the key tool to create a new kind of search engine for finding information in the web. 1 The need for topology in a search engine The purpose of a search engine is to find

Valentini, Silvio

413

TOPOLOGICAL STRING THEORY AND ENUMERATIVE GEOMETRY

TOPOLOGICAL STRING THEORY AND ENUMERATIVE GEOMETRY a dissertation submitted to the department) Approved for the University Committee on Graduate Studies: iii #12;TOPOLOGICAL STRING THEORY In this thesis we investigate several problems which have their roots in both topolog- ical string theory

Slatkin, Montgomery

414

Remarks on topological SUSY in sixdimensional TQFTs

We establish the existence of the topological vector supersymmetry in the six dimensional topological field theory for two-form fields introduced by Baulieu and West. We investigate the relation of these symmetries to the twist operation for the (2,0) supersymmetry and comment on their resemblance to the analogous symmetries in topological Yang-Mills theory.

Harald Ita; Karl Landsteiner; Thomas Pisar; Josef Rant; Manfred Schweda

1999-01-01

415

Substructure Topology Preserving Simplification of Tetrahedral Meshes

the power of our system with real world scientific datasets from electromagnetism simulations. 1 the topology of the mesh and of its substructures. Our system combines this topological validity testSubstructure Topology Preserving Simplification of Tetrahedral Meshes Fabien Vivodtzev1, Georges

Hahmann, Stefanie

416

Critical Points of the Electric Field from a Collection of Point Charges

The electric field around a molecule is generated by the charge distribution of its constituents: positively charged atomic nuclei, which are well approximated by point charges, and negatively charged electrons, whose probability density distribution can be computed from quantum mechanics. For the purposes of molecular mechanics or dynamics, the charge distribution is often approximated by a collection of point charges, with either a single partial charge at each atomic nucleus position, representing both the nucleus and the electrons near it, or as several different point charges per atom. The critical points in the electric field are useful in visualizing its geometrical and topological structure, and can help in understanding the forces and motion it induces on a charged ion or neutral dipole. Most visualization tools for vector fields use only samples of the field on the vertices of a regular grid, and some sort of interpolation, for example, trilinear, on the grid cells. There is less risk of missing or misinterpreting topological features if they can be derived directly from the analytic formula for the field, rather than from its samples. This work presents a method which is guaranteed to find all the critical points of the electric field from a finite set of point charges. To visualize the field topology, we have modified the saddle connector method to use the analytic formula for the field.

Max, N; Weinkauf, T

2007-02-16

417

Topologies for uninterruptible power supplies

The authors review the development of uninterruptible power supply (hereafter referred to as UPS) over the years from one with a SCR front end charger with isolation at line frequency to one with a sinusoidal current input charger with isolation at high frequency (HF). The authors discuss the developments in the single phase low-power (less than 1 kVA) UPS topologies.

R. Krishnan; S. Srinivasan

1993-01-01

418

Planar Graphs with Topological Constraints

We address in this paper the problem of constructing embeddings of planar graphs satisfying declarative, user-dened topological constraints. The constraints consist each of a cycle of the given graph and a set of its edges to be embedded inside this cycle and a set of its edges to be embedded outside this cycle. Their practical importance in graph visual- ization

Christoph Dornheim

2002-01-01

419

Floorplanning by Topological Constraint Reduction

The problem considered is that of producing a legal floorplan that respects a given topological constraint set. The floorplanning approach described is targeted for multilayer sea-of-cells based designs. Therefore it is assumed that no channel separations are required between the blocks. The approach can be generalized to incorporate channel separations

Gopalakrishnan Vijayan; Ren-song Tsay

1990-01-01

420

Topological Surface States of Antimony

Topological Surface States of Antimony Masih Mehdizadeh 10.08.2012 #12;Outline Introduction the electrons can occupy in the lattice #12;Back to Antimony: Surface States (SS) The electronic states (A) Y(A) 3000A x 3000A Topograph of Antimony (Sb) 0 500 1000 1500 2000 2500 3000 0 500 1000 1500 2000

Petta, Jason

421

Programming a Topological Quantum Computer

Topological quantum computing has recently proven itself to be a powerful computational model when constructing viable architectures for large scale computation. The topological model is constructed from the foundation of a error correction code, required to correct for inevitable hardware faults that will exist for a large scale quantum device. It is also a measurement based model of quantum computation, meaning that the quantum hardware is responsible only for the construction of a large, computationally universal quantum state. This quantum state is then strategically consumed, allowing for the realisation of a fully error corrected quantum algorithm. The number of physical qubits needed by the quantum hardware and the amount of time required to implement an algorithm is dictated by the manner in which this universal quantum state is consumed. In this paper we examine the problem of algorithmic optimisation in the topological lattice and introduce the required elements that will be needed when designing a classical software package to compile and implement a large scale algorithm on a topological quantum computer.

Simon J. Devitt; Kae Nemoto

2012-09-07

422

Topological Grammars for data analysis

Topological Grammars for data analysis Alexander Gorban, Leicester with Andrei Zinovyev, Paris and Neil Sumner, Leicester #12;Plan of the talk Two paradigms for data analysis: statistics and modelling #12;Two basic paradigms for data analysis Data set Statistical Analysis Data Modelling #12;Statistical

Gorban, Alexander N.

423

The topology of elementary submodels

Given a topological space ? X,T?, we take an elementary submodel M of a sufficiently large initial fragment of the universe containing ? X,T? and naturally define a space XM. We consider under what circumstances XM is a (nice image of a) subspace of X, and what properties of X are retained by XM.

Lúcia R. Junqueira; Franklin D. Tall

1998-01-01

424

Topology of Numbers Allen Hatcher

of the connection with the Pythagorean Theorem. Our goal will be a formula that gives them all. The ancient GreeksTopology of Numbers Allen Hatcher Chapter 0. Preview Pythagorean Triples. Rational Points on Other Quadratic Curves. Rational Points on a Sphere. Pythagorean Triples and Quadratic Forms. Pythagorean Triples

Hatcher, Allen

425

NASA Astrophysics Data System (ADS)

In this paper, a novel practical algorithmic solution for automatic discovering the physical topology of switched Ethernet was proposed. Our algorithm collects standard SNMP MIB information that is widely supported in modern IP networks and then builds the physical topology of the active network. We described the relative definitions, system model and proved the correctness of the algorithm. Practically, the algorithm was implemented in our visualization network monitoring system. We also presented the main steps of the algorithm, core codes and running results on the lab network. The experimental results clearly validate our approach, demonstrating that our algorithm is simple and effective which can discover the accurate up-to-date physical network topology.

Xiong, Yuting; Gu, Zhaojun; Jin, Wei

426

Charge fractionalization in nonchiral Luttinger systems

NASA Astrophysics Data System (ADS)

One-dimensional metals, such as quantum wires or carbon nanotubes, can carry charge in arbitrary units, smaller or larger than a single electron charge. However, according to Luttinger theory, which describes the low-energy excitations of such systems, when a single electron is injected by tunneling into the middle of such a wire, it will tend to break up into separate charge pulses, moving in opposite directions, which carry definite fractions f and (1-f) of the electron charge, determined by a parameter g that measures the strength of charge interactions in the wire. (The injected electron will also produce a spin excitation, which will travel at a different velocity than the charge excitations.) Observing charge fractionalization physics in an experiment is a challenge in those (nonchiral) low-dimensional systems which are adiabatically coupled to Fermi liquid leads. We theoretically discuss a first important step towards the observation of charge fractionalization in quantum wires based on momentum-resolved tunneling and multi-terminal geometries, and explain the recent experimental results of Steinberg et al. [H. Steinberg, G. Barak, A. Yacoby, L.N. Pfeiffer, K.W. West, B.I. Halperin, K. Le Hur, Nature Physics 4 (2008) 116].

Le Hur, Karyn; Halperin, Bertrand I.; Yacoby, Amir

2008-12-01

427

Charge fractionalization in nonchiral Luttinger systems

One-dimensional metals, such as quantum wires or carbon nanotubes, can carry charge in arbitrary units, smaller or larger than a single electron charge. However, according to Luttinger theory, which describes the low-energy excitations of such systems, when a single electron is injected by tunneling into the middle of such a wire, it will tend to break up into separate charge pulses, moving in opposite directions, which carry definite fractions f and (1-f) of the electron charge, determined by a parameter g that measures the strength of charge interactions in the wire. (The injected electron will also produce a spin excitation, which will travel at a different velocity than the charge excitations.) Observing charge fractionalization physics in an experiment is a challenge in those (nonchiral) low-dimensional systems which are adiabatically coupled to Fermi liquid leads. We theoretically discuss a first important step towards the observation of charge fractionalization in quantum wires based on momentum-resolved tunneling and multi-terminal geometries, and explain the recent experimental results of Steinberg et al. [H. Steinberg, G. Barak, A. Yacoby, L.N. Pfeiffer, K.W. West, B.I. Halperin, K. Le Hur, Nature Physics 4 (2008) 116].

Le Hur, Karyn [Department of Physics, Yale University, P.O. Box 208220, New Haven, CT 06520 (United States)], E-mail: karyn.lehur@yale.edu; Halperin, Bertrand I.; Yacoby, Amir [Department of Physics, Harvard University, Cambridge, MA 02138 (United States)

2008-12-15

428

Long Range Topological Order, the Chiral Condensate, and the Berry Connection in QCD

Topological insulators are substances which are bulk insulators but which carry current via special "topologically protected" edge states. The understanding of long range topological order in these systems is built around the idea of a Berry connection, which is a gauge connection obtained from the phase of the electron wave function transported over momentum space rather than coordinate space. The phase of a closed Wilson loop of the Berry connection around the Brillouin zone defines a topological order parameter which labels discrete flux vacua. The conducting states are surface modes on the domain walls between discrete vacua. Evidence from large-$N_c$ chiral dynamics, holographic QCD, and Monte Carlo observations has pointed to a picture of the QCD vacuum that is very similar to that of a topological insulator, with discrete quasivacua labelled by $\\theta$ angles that differ by mod $2\\pi$. In this picture, the domain walls are membranes of Chern-Simons charge, and the quark condensate consists of surface modes on these membranes, which are delocalized and thus support the long range propagation of Goldstone pions. The Berry phase in QED2 describes charge polarization of fermion-antifermion pairs, while in 4D QCD it describes the polarization of Chern-Simons membranes.

H. B. Thacker

2014-09-12

429

We use the Kontsevich-Miwa transform to relate the different pictures describing matter coupled to topological gravity in two dimensions: topological theories, Virasoro constraints on integrable hierarchies, and a DDK-type formalism. With the help of the Kontsevich-Miwa transform, we solve the Virasoro constraints on the KP hierarchy in terms of minimal models dressed with a (free) Liouville-like scalar. The dressing prescription originates in a topological (twisted N=2) theory. The Virasoro constraints are thus related to essentially the N=2 null state decoupling equations. The N=2 generators are constructed out of matter, the `Liouville' scalar, and $c=-2$ ghosts. By a `dual' construction involving the reparametrization $c=-26$ ghosts, the DDK dressing prescription is reproduced from the N=2 symmetry. As a by-product we thus observe that there are two ways to dress arbitrary $d\\leq1$ or $d\\geq25$ matter theory, that allow its embedding into a topological theory. By th e Kontsevich-Miwa transform, which introduces an infinite set of `time' variables $t_r$, the equations ensuring the vanishing of correlators that involve BRST-exact primary states, factorize through the Virasoro generators expressed in terms of the $t_r$. The background charge of these Virasoro generators is determined by the topological central charge.

B Gato-Rivera; A M Semikhatov

1992-12-18

430

Topology of molecular interaction networks

Molecular interactions are often represented as network models which have become the common language of many areas of biology. Graphs serve as convenient mathematical representations of network models and have themselves become objects of study. Their topology has been intensively researched over the last decade after evidence was found that they share underlying design principles with many other types of networks. Initial studies suggested that molecular interaction network topology is related to biological function and evolution. However, further whole-network analyses did not lead to a unified view on what this relation may look like, with conclusions highly dependent on the type of molecular interactions considered and the metrics used to study them. It is unclear whether global network topology drives function, as suggested by some researchers, or whether it is simply a byproduct of evolution or even an artefact of representing complex molecular interaction networks as graphs. Nevertheless, network biology has progressed significantly over the last years. We review the literature, focusing on two major developments. First, realizing that molecular interaction networks can be naturally decomposed into subsystems (such as modules and pathways), topology is increasingly studied locally rather than globally. Second, there is a move from a descriptive approach to a predictive one: rather than correlating biological network topology to generic properties such as robustness, it is used to predict specific functions or phenotypes. Taken together, this change in focus from globally descriptive to locally predictive points to new avenues of research. In particular, multi-scale approaches are developments promising to drive the study of molecular interaction networks further. PMID:24041013

2013-01-01

431

Field Theories of Topological Random Walks

In this work we derive certain topological theories of transverse vector fields whose amplitudes reproduce topological invariants involving the interactions among the trajectories of three and four random walks. This result is applied to the construction of a field theoretical model which describes the statistical mechanics of an arbitrary number of topologically linked polymers in the context of the analytical approach of Edwards. With respect to previous attempts, our approach is very general, as it can treat a system involving an arbitrary number of polymers and the topological states are not only specified by the Gauss linking number, but also by higher order topological invariants.

Franco Ferrari; Ignazio Lazzizzera

1999-06-14

432

Topology Discovery Using Cisco Discovery Protocol

In this paper we address the problem of discovering network topology in proprietary networks. Namely, we investigate topology discovery in Cisco-based networks. Cisco devices run Cisco Discovery Protocol (CDP) which holds information about these devices. We first compare properties of topologies that can be obtained from networks deploying CDP versus Spanning Tree Protocol (STP) and Management Information Base (MIB) Forwarding Database (FDB). Then we describe a method of discovering topology of CDP-based networks. Our experiments show that the physical topology of the network including links that are in Forwarding Block state can be discovered.

Rodriguez, Sergio R

2009-01-01

433

Topological aspects of polarization structured beams

NASA Astrophysics Data System (ADS)

Polarization structured optical beams have half-integer topological structures: star, lemon, monstar in ?-symmetric polarization ellipse orientation tensor field and integer-index topological structures: saddle, spiral, node in 2?-symmetric Poynting vector field. Topological approach to study the polarization structured optical beams is carried out and presented here in some detail. These polarization structured light beams are demonstrated to be the best platform to explore the topological interdependencies. The dependence of one type of topological structure on the other is used to control the Poynting vector density distribution and locally enhance the angular momentum density as compared to its constituent beam fields.

Kumar, Vijay; Viswanathan, Nirmal K.

2014-02-01

434

A computational investigation of topological insulator Bi2Se3 film

NASA Astrophysics Data System (ADS)

Topological insulators have a bulk band gap like an ordinary insulator and conducting states on their edge or surface which are formed by spin-orbit coupling and protected by time-reversal symmetry. We report theoretical analyses of the electronic properties of three-dimensional topological insulator Bi2Se3 film on different energies. We choose five different energies (-123, -75, 0, 180, 350 meV) around the Dirac cone (-113 meV). When energy is close to the Dirac cone, the properties of wave function match the topological insulator's hallmark perfectly. When energy is far way from the Dirac cone, the hallmark of topological insulator is broken and the helical states disappear. The electronic properties of helical states are dug out from the calculation results. The spin-momentum locking of the helical states are confirmed. A 3-fold symmetry of the helical states in Brillouin zone is also revealed. The penetration depth of the helical states is two quintuple layers which can be identified from layer projection. The charge contribution on each quintuple layer depends on the energy, and has completely different behavior along K and M direction in Brillouin zone. From orbital projection, we can find that the maximum charge contribution of the helical states is p z orbit and the charge contribution on p y and p x orbits have 2-fold symmetry.

Hu, Yi-Bin; Zhao, Yong-Hong; Wang, Xue-Feng

2014-12-01

435

Uniqueness theorem for charged dipole rings in five-dimensional minimal supergravity

We show a uniqueness theorem for charged dipole rotating black rings in the bosonic sector of five-dimensional minimal supergravity, generalizing our previous work [arXiv:0901.4724] on the uniqueness of charged rotating black holes with topologically spherical horizon in the same theory. More precisely, assuming the existence of two commuting axial Killing vector fields and the same rod structure as the known solutions, we prove that an asymptotically flat, stationary charged rotating black hole with nondegenerate connected event horizon of cross-section topology S{sup 1}xS{sup 2} in the five-dimensional Einstein-Maxwell-Chern-Simons theory - if exists - is characterized by the mass, charge, two independent angular momenta, dipole charge, and the ratio of the S{sup 2} radius to the S{sup 1} radius. As anticipated, the necessity of specifying dipole charge - which is not a conserved charge - is the new, distinguished ingredient that highlights difference between the present theorem and the corresponding theorem for vacuum case, as well as difference from the case of topologically spherical horizon within the same minimal supergravity. We also consider a similar boundary value problem for other topologically nontrivial black holes within the same theory, and in particular, discuss some nontrivial issues that arise when attempting to generalize the present uniqueness results to include black lenses--provided there exists such a solution in the theory.

Tomizawa, Shinya; Ishibashi, Akihiro [KEK Theory Center, Institute of Particle and Nuclear Studies, KEK, Tsukuba, Ibaraki, 305-0801 (Japan); Yasui, Yukinori [Department of Mathematics and Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585 (Japan)

2010-04-15

436

NASA Astrophysics Data System (ADS)

Polymer dispersed liquid crystals are a useful model system for studying the relationship between surface topology and defect structures. They are comprised of a polymer matrix with suspended spherical nematic drops and are topologically constrained to host defects of an elementary hedgehog charge per droplet, such as bulk or surface point defects or closed disclination loops. We control the genus of the closed surfaces confining such micrometer-sized nematic drops with tangential boundary conditions for molecular alignment imposed by the polymer matrix, allowing us to avoid defects or, on the contrary, to generate them in a controlled way. We show, both experimentally and through numerical modeling, that topological constraints in nematic microdrops can be satisfied by hosting topologically stable half-integer bulk defect lines anchored to opposite sides of handlebody surfaces. This enriches the interplay of topologies of closed surfaces and fields with nonpolar symmetry, yielding new unexpected configurations that cannot be realized in vector fields, having potential implications for topologically similar defects in cosmology and other fields.

Campbell, Michael G.; Tasinkevych, Mykola; Smalyukh, Ivan I.

2014-05-01

437

Polymer dispersed liquid crystals are a useful model system for studying the relationship between surface topology and defect structures. They are comprised of a polymer matrix with suspended spherical nematic drops and are topologically constrained to host defects of an elementary hedgehog charge per droplet, such as bulk or surface point defects or closed disclination loops. We control the genus of the closed surfaces confining such micrometer-sized nematic drops with tangential boundary conditions for molecular alignment imposed by the polymer matrix, allowing us to avoid defects or, on the contrary, to generate them in a controlled way. We show, both experimentally and through numerical modeling, that topological constraints in nematic microdrops can be satisfied by hosting topologically stable half-integer bulk defect lines anchored to opposite sides of handlebody surfaces. This enriches the interplay of topologies of closed surfaces and fields with nonpolar symmetry, yielding new unexpected configurations that cannot be realized in vector fields, having potential implications for topologically similar defects in cosmology and other fields. PMID:24877965

Campbell, Michael G; Tasinkevych, Mykola; Smalyukh, Ivan I

2014-05-16

438

Constructing a logical, regular axis topology from an irregular topology

Constructing a logical regular topology from an irregular topology including, for each axial dimension and recursively, for each compute node in a subcommunicator until returning to a first node: adding to a logical line of the axial dimension a neighbor specified in a nearest neighbor list; calling the added compute node; determining, by the called node, whether any neighbor in the node's nearest neighbor list is available to add to the logical line; if a neighbor in the called compute node's nearest neighbor list is available to add to the logical line, adding, by the called compute node to the logical line, any neighbor in the called compute node's nearest neighbor list for the axial dimension not already added to the logical line; and, if no neighbor in the called compute node's nearest neighbor list is available to add to the logical line, returning to the calling compute node.

Faraj, Daniel A.

2014-07-01

439

Constructing a logical, regular axis topology from an irregular topology

Constructing a logical regular topology from an irregular topology including, for each axial dimension and recursively, for each compute node in a subcommunicator until returning to a first node: adding to a logical line of the axial dimension a neighbor specified in a nearest neighbor list; calling the added compute node; determining, by the called node, whether any neighbor in the node's nearest neighbor list is available to add to the logical line; if a neighbor in the called compute node's nearest neighbor list is available to add to the logical line, adding, by the called compute node to the logical line, any neighbor in the called compute node's nearest neighbor list for the axial dimension not already added to the logical line; and, if no neighbor in the called compute node's nearest neighbor list is available to add to the logical line, returning to the calling compute node.

Faraj, Daniel A.

2014-07-22

440

A tunable topological insulator in the spin helical Dirac transport regime.

Helical Dirac fermions-charge carriers that behave as massless relativistic particles with an intrinsic angular momentum (spin) locked to its translational momentum-are proposed to be the key to realizing fundamentally new phenomena in condensed matter physics. Prominent examples include the anomalous quantization of magneto-electric coupling, half-fermion states that are their own antiparticle, and charge fractionalization in a Bose-Einstein condensate, all of which are not possible with conventional Dirac fermions of the graphene variety. Helical Dirac fermions have so far remained elusive owing to the lack of necessary spin-sensitive measurements and because such fermions are forbidden to exist in conventional materials harbouring relativistic electrons, such as graphene or bismuth. It has recently been proposed that helical Dirac fermions may exist at the edges of certain types of topologically ordered insulators-materials with a bulk insulating gap of spin-orbit origin and surface states protected against scattering by time-reversal symmetry-and that their peculiar properties may be accessed provided the insulator is tuned into the so-called topological transport regime. However, helical Dirac fermions have not been observed in existing topological insulators. Here we report the realization and characterization of a tunable topological insulator in a bismuth-based class of material by combining spin-imaging and momentum-resolved spectroscopies, bulk charge compensation, Hall transport measurements and surface quantum control. Our results reveal a spin-momentum locked Dirac cone carrying a non-trivial Berry's phase that is nearly 100 per cent spin-polarized, which exhibits a tunable topological fermion density in the vicinity of the Kramers point and can be driven to the long-sought topological spin transport regime. The observed topological nodal state is shown to be protected even up to 300 K. Our demonstration of room-temperature topological order and non-trivial spin-texture in stoichiometric Bi(2)Se(3).M(x) (M(x) indicates surface doping or gating control) paves the way for future graphene-like studies of topological insulators, and applications of the observed spin-polarized edge channels in spintronic and computing technologies possibly at room temperature. PMID:19620959

Hsieh, D; Xia, Y; Qian, D; Wray, L; Dil, J H; Meier, F; Osterwalder, J; Patthey, L; Checkelsky, J G; Ong, N P; Fedorov, A V; Lin, H; Bansil, A; Grauer, D; Hor, Y S; Cava, R J; Hasan, M Z

2009-08-27

441

NASA Astrophysics Data System (ADS)

A one-dimensional topological superconductor features a single fermionic zero mode that is delocalized over two Majorana bound states located at the ends of the system. We study a pair of spatially separated nanomechanical oscillators tunnel coupled to these Majorana modes. Most interestingly, we demonstrate that the combination of electron-phonon coupling and a finite charging energy on the mesoscopic topological superconductor can lead to an effective superexchange between the oscillators via the nonlocal fermionic zero mode. We further show that this electron teleportation mechanism leads to entanglement of the two oscillators over distances that can significantly exceed the coherence length of the superconductor.

Walter, Stefan; Budich, Jan Carl

2014-04-01

442

Polymer Amide as an Early Topology

Hydrophobic polymer amide (HPA) could have been one of the first normal density materials to accrete in space. We present ab initio calculations of the energetics of amino acid polymerization via gas phase collisions. The initial hydrogen-bonded di-peptide is sufficiently stable to proceed in many cases via a transition state into a di-peptide with an associated bound water molecule of condensation. The energetics of polymerization are only favorable when the water remains bound. Further polymerization leads to a hydrophobic surface that is phase-separated from, but hydrogen bonded to, a small bulk water complex. The kinetics of the collision and subsequent polymerization are discussed for the low-density conditions of a molecular cloud. This polymer in the gas phase has the properties to make a topology, viz. hydrophobicity allowing phase separation from bulk water, capability to withstand large temperature ranges, versatility of form and charge separation. Its flexible tetrahedral carbon atoms that alternate with more rigid amide groups allow it to deform and reform in hazardous conditions and its density of hydrogen bonds provides adhesion that would support accretion to it of silicon and metal elements to form a stellar dust material. PMID:25048204

McGeoch, Julie E. M.; McGeoch, Malcolm W.

2014-01-01

443

Topological effects on the magnetoconductivity in topological insulators

NASA Astrophysics Data System (ADS)

Three-dimensional strong topological insulators (TIs) guarantee the existence of a two-dimensional (2-D) conducting surface state which completely covers the surface of the TI. The TI surface state necessarily wraps around the TI's top, bottom, and two sidewalls, and is therefore topologically distinct from ordinary 2-D electron gases (2-DEGs) which are planar. This has several consequences for the magnetoconductivity ? ? , a frequently studied measure of weak antilocalization which is sensitive to the quantum coherence time ?? and to temperature. We show that conduction on the TI sidewalls systematically reduces ? ? , multiplying it by a factor which is always less than one and decreases in thicker samples. In addition, we present both an analytical formula and numerical results for the tilted-field magnetoconductivity which has been measured in several experiments. Lastly, we predict that as the temperature is reduced ? ? will enter a wrapped regime where it is sensitive to diffusion processes which make one or more circuits around the TI. In this wrapped regime the magnetoconductivity's dependence on temperature, typically 1 /T2 in 2-DEGs, disappears. We present numerical and analytical predictions for the wrapped regime at both small and large field strengths. The wrapped regime and topological signatures discussed here should be visible in the same samples and at the same temperatures where the Altshuler-Aronov-Spivak (AAS) effect has already been observed, when the measurements are repeated with the magnetic field pointed perpendicularly to the TI's top face.

Sacksteder, Vincent E.; Arnardottir, Kristin Bjorg; Kettemann, Stefan; Shelykh, Ivan A.

2014-12-01

444

As a point of departure it is suggested that Quantum Cosmology is a topological concept independent from metrical constraints. Methods of continuous topological evolution and topological thermodynamics are used to construct a cosmological model of the present universe, using the techniques based upon Cartan's theory of exterior differential systems. Thermodynamic domains, which are either Open, Closed, Isolated, or in Equilibrium, can be put into correspondence with topological systems of Pfaff topological dimension 4, 3, 2 and 1. If the environment of the universe is assumed to be a physical vacuum of Pfaff topological dimension 4, then continuous but irreversible topological evolution can cause the emergence of topologically coherent defect structures of Pfaff topological dimension less than 4. As galaxies and stars exchange radiation but not matter with the environment, they are emergent topological defects of Pfaff topological dimension 3 which are far from equilibrium. DeRham topological theory of period integrals over closed but not exact exterior differential systems leads to the emergence of quantized, deformable, but topologically coherent, singular macrostates at all scales. The method leads to the conjecture that dark matter and energy is represented by those thermodynamic topological defect structures of Pfaff dimension 2 or less.

R. M. Kiehn

2006-03-17

445

Information topologies on non-commutative state spaces

We investigate the I-topology and the rI-topology on the state spaces of a C*-subalgebra of Mat(n,C). These are defined in terms of convergence of the relative entropy. The I-topology includes the rI-topology, which includes the norm topology. These topologies share some properties with a metric topology, in particular their open sets are unions of disks arising from the relative entropy.

Stephan Weis

2010-01-01

446

We discuss physical properties of `integer' topological phases of bosons in D=3+1 dimensions, protected by internal symmetries like time reversal and/or charge conservation. These phases invoke interactions in a fundamental way but do not possess topological order and are bosonic analogs of free fermion topological insulators and superconductors. While a formal cohomology based classification of such states was recently discovered, their physical properties remain mysterious. Here we develop a field theoretic description of several of these states and show that they possess unusual surface states, which if gapped, must either break the underlying symmetry, or develop topological order. In the latter case, symmetries are implemented in a way that is forbidden in a strictly two dimensional theory. While this is the usual fate of the surface states, exotic gapless states can also be realized. For example, tuning parameters can naturally lead to a deconfined quantum critical point or, in other situations, a fully symmetric vortex metal phase. We discuss cases where the topological phases are characterized by quantized magnetoelectric response \\theta, which, somewhat surprisingly, is an odd multiple of 2\\pi. Two different surface theories are shown to capture these phenomena - the first is a nonlinear sigma model with a topological term. The second invokes vortices on the surface that transform under a projective representation of the symmetry group. A bulk field theory consistent with these properties is identified, which is a multicomponent `BF' theory supplemented, crucially, with a topological term. A possible topological phase characterized by the thermal analog of the magnetoelectric effect is also discussed.

Ashvin Vishwanath; T. Senthil

2013-01-09

447

Topological Open Strings on Orbifolds

NASA Astrophysics Data System (ADS)

We use the remodeling approach to the B-model topological string in terms of recursion relations to study open string amplitudes at orbifold points. To this end, we clarify modular properties of the open amplitudes and rewrite them in a form that makes their transformation properties under the modular group manifest. We exemplify this procedure for the {{mathbb C}^3/{mathbb Z}_3} orbifold point of local {{mathbb P}^2}, where we present results for topological string amplitudes for genus zero and up to three holes, and for the one-holed torus. These amplitudes can be understood as generating functions for either open orbifold Gromov-Witten invariants of {{mathbb C}^3/{mathbb Z}_3}, or correlation functions in the orbifold CFT involving insertions of both bulk and boundary operators.

Bouchard, Vincent; Klemm, Albrecht; Mariño, Marcos; Pasquetti, Sara

2010-06-01

448

Membrane topology of hedgehog acyltransferase.

Hedgehog acyltransferase (Hhat) is a multipass transmembrane enzyme that mediates the covalent attachment of the 16-carbon fatty acid palmitate to the N-terminal cysteine of Sonic Hedgehog (Shh). Palmitoylation of Shh by Hhat is critical for short and long range signaling. Knowledge of the topological organization of Hhat transmembrane helices would enhance our understanding of Hhat-mediated Shh palmitoylation. Bioinformatics analysis of transmembrane domains within human Hhat using 10 different algorithms resulted in highly consistent predictions in the C-terminal, but not in the N-terminal, region of Hhat. To empirically determine the topology of Hhat, we designed and exploited Hhat constructs containing either terminal or 12 different internal epitope tags. We used selective permeabilization coupled with immunofluorescence as well as a protease protection assay to demonstrate that Hhat contains 10 transmembrane domains and 2 re-entrant loops. The invariant His and highly conserved Asp residues within the membrane-bound O-acyltransferase (MBOAT) homology domain are segregated on opposite sides of the endoplasmic reticulum membrane. The localization of His-379 on the lumenal membrane surface is consistent with a role for this invariant residue in catalysis. Analysis of the activity and stability of the Hhat constructs revealed that the C-terminal MBOAT domain is especially sensitive to manipulation. Moreover, there was remarkable similarity in the overall topological organization of Hhat and ghrelin O-acyltransferase, another MBOAT family member. Knowledge of the topological organization of Hhat could serve as an important tool for further design of selective Hhat inhibitors. PMID:25488661

Matevossian, Armine; Resh, Marilyn D

2015-01-23

449

Topological defects in extended inflation

NASA Technical Reports Server (NTRS)

The production of topological defects, especially cosmic strings, in extended inflation models was considered. In extended inflation, the Universe passes through a first-order phase transition via bubble percolation, which naturally allows defects to form at the end of inflation. The correlation length, which determines the number density of the defects, is related to the mean size of bubbles when they collide. This mechanism allows a natural combination of inflation and large scale structure via cosmic strings.

Copeland, Edmund J.; Kolb, Edward W.; Liddle, Andrew R.

1990-01-01

450

Topological Insulator Nanowires and Nanoribbons

Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi{sub 2}Se{sub 3} material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi{sub 2}Se{sub 3} nanomaterials with a variety of morphologies. The synthesis of Bi{sub 2}Se{sub 3} nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [11-20] direction with a rectangular crosssection and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with {approx}1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitals to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states.

Kong, D.S.

2010-06-02

451

Definitions of Entomological Terms

NSDL National Science Digital Library

A list of of morphological definitions and word roots useful to Entomology students and teachers. The list contains concise and easily understandable definitions for a number of morphological and physiological terms and specifies where on the insect these terms apply. A good reference for students in introductory entomology or insect morphology classes. Requires Adobe Acrobat Reader or equivalent software to read .pdf documents.

0000-00-00

452

are a digestive system response and are much more common than food allergies. Food Allergy vs. Food Intolerance's digestive system or when a person is unable to properly digest a food. SYMPTOMS: Symptoms of an AllergicFood Allergies DEFINITIONS: Definition of a Food Allergy: Immune system response to a food

Maxwell, Bruce D.

453

Search for New Topological Insulators

NASA Astrophysics Data System (ADS)

Topological insulators (TIs) host a novel quantum phase of electrons which is characterized by topologically protected surface states originating from the effects of spin-orbit and time-reversal symmetries. While several families of TIs have already been found, the intense world-wide search for new classes of TIs continues unabated. This interest is driven by the need for materials with greater structural flexibility and tunability to enable viable applications in spintronics and quantum computing. We have used first-principles band theory computations in combination with angle-resolved photoemission experiments to successfully predict many new classes of topologically interesting materials, including Bi2Se3 series, the ternary half-Heusler compounds, thallium-based chalcogenides, and the Li2AgSb and GenBi2mTe3m+n families. [1-5] Work supported by the Office of Basic Energy Sciences, US DOE.[4pt] [1] H. Lin, R. S. Markiewicz, L. A. Wray, L. Fu, M. Z. Hasan, and A. Bansil, Physical Review Letters 105, 036404 (2010). [0pt] [2] H. Lin, L. A. Wray, Y. Xia. S. Y. Xu, S. Jia, R. J. Cava, A. Bansil, and M. Z. Hasan, Nature Materials 9, 546 (2010). [0pt] [3] W. Al-Sawai et al., Physical Review B 82, 125208 (2010). [0pt] [4] L. A. Wray et al., Nature Physics (2010, in press).[0pt] [5] S.-Y. Xu et al., arXiv:1007.5111 (2010).

Lin, Hsin; Wray, L. A.; Xu, S.-Y.; Hasan, M. Z.; Das, T.; Wang, Y. J.; Markiewicz, R. S.; Bansil, Arun

2011-03-01

454

Interacting topological phases and quantum anomalies

NASA Astrophysics Data System (ADS)

Since the quantum Hall effect, the notion of topological phases of matter has been extended to those that are well-defined (or: ``protected'') in the presence of a certain set of symmetries, and that exist in dimensions higher than two. In the (fractional) quantum Hall effects (and in ``chiral'' topological phases in general), Laughlin's thought experiment provides a key insight into their topological characterization; it shows a close connection between topological phases and quantum anomalies. Compared to genuine topological phases, symmetry protected topological phases are more fragile and less entangled states of matter, and hence for their characterization we need to sharpen our understanding on how topological properties of the systems manifest themselves in the form of a quantum anomaly. By taking various kinds of symmetry protected topological phases as an example, I will demonstrate that quantum anomalies serve as a useful tool to diagnose (and even define) topological properties of the systems. I will also discuss quantum anomalies play an essential role when developing descriptions of these topological phases in terms bulk and boundary (effective) theories.

Ryu, Shinsei

2013-03-01

455

The definition of cross polarization

There are at least three different definitions of cross polarization used in the literature. The alternative definitions are discussed with respect to several applications, and the definition which corresponds to one standard measurement practice is proposed as the best choice.

A. Ludwig

1973-01-01

456

Photonic simulation of topological excitations in metamaterials.

Condensed matter systems with topological order and metamaterials with left-handed chirality have attracted recently extensive interests in the fields of physics and optics. So far the topological order and chirality of electromagnetic wave are two independent concepts, and there is no work to address their connection. Here we propose to establish the relation between the topological order in condensed matter systems and the chirality in metamaterials, by mapping explicitly Maxwell's equations to the Dirac equation in one dimension. We report an experimental implement of the band inversion in the Dirac equation, which accompanies change of chirality of electromagnetic wave in metamaterials, and the first microwave measurement of topological excitations and topological phases in one dimension. Our finding provides a proof-of-principle example that electromagnetic wave in the metamaterials can be used to simulate the topological order in condensed matter systems and quantum phenomena in relativistic quantum mechanics in a controlled laboratory environment. PMID:24452532

Tan, Wei; Sun, Yong; Chen, Hong; Shen, Shun-Qing

2014-01-01

457

Circuit topology of proteins and nucleic acids.

Folded biomolecules display a bewildering structural complexity and diversity. They have therefore been analyzed in terms of generic topological features. For instance, folded proteins may be knotted, have beta-strands arranged into a Greek-key motif, or display high contact order. In this perspective, we present a method to formally describe the topology of all folded linear chains and hence provide a general classification and analysis framework for a range of biomolecules. Moreover, by identifying the fundamental rules that intrachain contacts must obey, the method establishes the topological constraints of folded linear chains. We also briefly illustrate how this circuit topology notion can be applied to study the equivalence of folded chains, the engineering of artificial RNA structures and DNA origami, the topological structure of genomes, and the role of topology in protein folding. PMID:25126961

Mashaghi, Alireza; van Wijk, Roeland J; Tans, Sander J

2014-09-01

458

Topological crystalline insulators in transition metal oxides.

Topological crystalline insulators possess electronic states protected by crystal symmetries, rather than time-reversal symmetry. We show that the transition metal oxides with heavy transition metals are able to support nontrivial band topology resulting from mirror symmetry of the lattice. As an example, we consider pyrochlore oxides of the form A2M2O7. As a function of spin-orbit coupling strength, we find two Z2 topological insulator phases can be distinguished from each other by their mirror Chern numbers, indicating a different topological crystalline insulators. We also derive an effective k·p Hamiltonian, similar to the model introduced for Pb(1-x)Sn(x)Te, and discuss the effect of an on-site Hubbard interaction on the topological crystalline insulator phase using slave-rotor mean-field theory, which predicts new classes of topological quantum spin liquids. PMID:25167290

Kargarian, Mehdi; Fiete, Gregory A

2013-04-12

459

Imaging topological edge states in silicon photonics

NASA Astrophysics Data System (ADS)

Topological features--global properties not discernible locally--emerge in systems ranging from liquid crystals to magnets to fractional quantum Hall systems. A deeper understanding of the role of topology in physics has led to a new class of matter--topologically ordered systems. The best known examples are quantum Hall effects, where insensitivity to local properties manifests itself as conductance through edge states that is insensitive to defects and disorder. Current research into engineering topological order primarily focuses on analogies to quantum Hall systems, where the required magnetic field is synthesized in non-magnetic systems. Here, we realize synthetic magnetic fields for photons at room temperature, using linear silicon photonics. We observe, for the first time, topological edge states of light in a two-dimensional system and show their robustness against intrinsic and introduced disorder. Our experiment demonstrates the feasibility of using photonics to realize topological order in both non-interacting and many-body regimes.

Hafezi, M.; Mittal, S.; Fan, J.; Migdall, A.; Taylor, J. M.

2013-12-01

460

Topological phase transitions in superradiance lattices

The discovery of the quantum Hall effect (QHE) reveals a new class of matter phases, topological insulators (TI's), which have been extensively studied in solid-state materials and recently in photonic structures, time-periodic systems and optical lattices of cold atoms. All these topological systems are lattices in real space. Our recent study shows that Scully's timed Dicke states (TDS) can form a superradiance lattice (SL) in momentum space. Here we report the discovery of topological phase transitions in a two-dimensional SL in electromagnetically induced transparency (EIT). By periodically modulating the three EIT coupling fields, we can create a Haldane model with in-situ tunable topological properties. The Chern numbers of the energy bands and hence the topological properties of the SL manifest themselves in the contrast between diffraction signals emitted by superradiant TDS. The topological superradiance lattices (TSL) provide a controllable platform for simulating exotic phenomena in condensed matte...

Wang, Da-Wei; Yuan, Luqi; Liu, Ren-Bao; Zhu, Shi-Yao

2015-01-01

461

Topological Properties of Ultracold Bosons in One-Dimensional Quasiperiodic Optical Lattice

NASA Astrophysics Data System (ADS)

We analyze the topological properties of the one-dimensional Bose–Hubbard model with a quasiperiodic superlattice potential. This system can be realized in interacting ultracold bosons in an optical lattice in the presence of an incommensurate superlattice potential. We first analyze the quasiperiodic superlattice formed by the cosine function, which we call the Harper-like Bose–Hubbard model. We compute the Chern number and observe gap-closing behavior as the interaction strength U is changed. Also, we discuss the bulk-edge correspondence in our system. Furthermore, we explore the phase diagram as a function of U and a continuous deformation parameter ? between the Harper-like model and another important quasiperiodic lattice, the Fibonacci model. We numerically confirm that the incommensurate charge density wave (ICDW) phase is topologically nontrivial and that it is topologically equivalent in the whole ICDW region.

Matsuda, Fuyuki; Tezuka, Masaki; Kawakami, Norio

2014-08-01

462

Metastable configurations formed by defects, inclusions, elastic deformations and topological solitons in liquid crystals are a promising choice for building photonic crystals and metamaterials with a potential for new optical applications. Local optical modification of the director or introduction of colloidal inclusions into a moderately chiral nematic liquid crystal confined to a homeotropic cell creates localized multistable chiral solitons. Here we induce solitons that "dress" the dispersed spherical particles treated for tangential degenerate boundary conditions, and perform controlled switching of their state using focused optical beams. Two optically switchable distinct metastable states, toron and hopfion, bound to colloidal spheres into structures with different topological charges are investigated. Their structures are examined using Q-tensor based numerical simulations and compared to the profiles reconstructed from the experiments. A topological explanation of observed multistability is constructed. PMID:25477195

Porenta, T; Copar, S; Ackerman, P J; Pandey, M B; Varney, M C M; Smalyukh, I I; Žumer, S

2014-01-01

463

Aging and reduced bulk conductance in thin films of the topological insulator Bi2Se3

NASA Astrophysics Data System (ADS)

We report on the effect of exposure to atmospheric conditions on the THz conductivity of thin films of the topological insulator Bi2Se3. We find (1) two contributions of mobile charge carriers to the THz conductivity immediately after growth and (2) the spectral weight of the smaller of these decays significantly over a period of several days as the film is exposed to ambient conditions, while the other remains relatively constant. We associate the former with a bulk response and the latter with the surface. The surface response exhibits the expected robustness of the carriers from 2D topological surface states. We find no evidence for a third spectral feature derived from topologically trivial surface states.

Valdés Aguilar, R.; Wu, L.; Stier, A. V.; Bilbro, L. S.; Brahlek, M.; Bansal, N.; Oh, S.; Armitage, N. P.

2013-04-01

464

NASA Astrophysics Data System (ADS)

Metastable configurations formed by defects, inclusions, elastic deformations and topological solitons in liquid crystals are a promising choice for building photonic crystals and metamaterials with a potential for new optical applications. Local optical modification of the director or introduction of colloidal inclusions into a moderately chiral nematic liquid crystal confined to a homeotropic cell creates localized multistable chiral solitons. Here we induce solitons that ``dress'' the dispersed spherical particles treated for tangential degenerate boundary conditions, and perform controlled switching of their state using focused optical beams. Two optically switchable distinct metastable states, toron and hopfion, bound to colloidal spheres into structures with different topological charges are investigated. Their structures are examined using Q-tensor based numerical simulations and compared to the profiles reconstructed from the experiments. A topological explanation of observed multistability is constructed.

Porenta, T.; ?opar, S.; Ackerman, P. J.; Pandey, M. B.; Varney, M. C. M.; Smalyukh, I. I.; Žumer, S.

2014-12-01

465

Recently, it was realized that quantum states of matter can be classified as long-range entangled states (i.e., with nontrivial topological order) and short-range entangled states (i.e., with trivial topological order). ...

Wen, Xiao-Gang

466

A CLASSIFICATION OF ORDINAL TOPOLOGIES VINCENT KIEFTENBELD AND BENEDIKT LOWE

topologies; we call these ordinal topologies. These topologies have many discrete points: if A CLASSIFICATION OF ORDINAL TOPOLOGIES VINCENT KIEFTENBELD AND BENEDIKT LÂ¨OWE Abstract. Ordinals types of all ordinal topologies using the Cantor normal form and the notion of the CantorÂBendixson rank

Amsterdam, University of

467

Immirzi parameter and Noether charges in first order gravity

The framework of SO(3,2) constrained BF theory applied to gravity makes it possible to generalize formulas for gravitational diffeomorphic Noether charges (mass, angular momentum, and entropy). It extends Wald's approach to the case of first order gravity with a negative cosmological constant, the Holst modification and the topological terms (Nieh-Yan, Euler, and Pontryagin). Topological invariants play essential role contributing to the boundary terms in the regularization scheme for the asymptotically AdS spacetimes, so that the differentiability of the action is automatically secured. Intriguingly, it turns out that the black hole thermodynamics does not depend on the Immirzi parameter for the AdS-Schwarzschild, AdS-Kerr, and topological black holes, whereas a nontrivial modification appears for the AdS-Taub-NUT spacetime, where it impacts not only the entropy, but also the total mass.

R. Durka

2011-11-08

468

Some Results Related to Soft Topological Spaces

The notion of soft sets is introduced as a general mathematical tool for dealing with uncertainty. In this paper, we consider the concepts of soft compactness, countably soft compactness and obtain some results. We study some soft separation axioms that have been studied by Min and Shabir-Naz. By constructing a special soft topological space, show that some classical results in general topology are not true about soft topological spaces, for instance every compact Housdorff spaces need not be normal.

E. Peyghan; B. Samadi; A. Tayebi

2014-01-21

469

Algebra and topology for applications to physics

NASA Technical Reports Server (NTRS)

The principal concepts of algebra and topology are examined with emphasis on applications to physics. In particular, attention is given to sets and mapping; topological spaces and continuous mapping; manifolds; and topological groups and Lie groups. The discussion also covers the tangential spaces of the differential manifolds, including Lie algebras, vector fields, and differential forms, properties of differential forms, mapping of tangential spaces, and integration of differential forms.

Rozhkov, S. S.

1987-01-01

470

Magnetic topological transition in transmission line metamaterials

NASA Astrophysics Data System (ADS)

We study the magnetic topological transition of the isofrequency curves in the wave vector space from a closed ellipsoid to an open hyperboloid in a metamaterial based on artificial transmission lines. In the radio frequency band we directly measure the emission pattern of a point source placed in the center of the lattice and demonstrate the elliptical wave fronts below the topological transition frequency and hyperbolic wave fronts above the topological transition frequency.

Shchelokova, Alena V.; Filonov, Dmitry S.; Kapitanova, Polina V.; Belov, Pavel A.

2014-09-01

471

NSDL National Science Digital Library

In this activity about electricity, learners produce a spark that they can feel, see, and hear. Learners rub a Styrofoam plate with wool to give it an electric charge. Then, they use the charged Styrofoam to charge an aluminum pie pan. Essentially, learners build an electrophorus (Greek for "charge carrier"). This resource also contains instructions on how to build a large charge carrier called a "Leyden Jar" using a plastic film can.

2012-06-26

472

Quantum Axiomatics: Topological and Classical Properties of State Property Systems

NASA Astrophysics Data System (ADS)

The definition of `classical state' from (Aerts in K. Engesser, D. Gabbay and D. Lehmann (Eds.), Handbook of Quantum Logic and Quantum Structures. Elsevier, Amsterdam, 2009), used e.g. in Aerts et al. ( http://arxiv.org/abs/quant-ph/0503083 , 2010) to prove a decomposition theorem internally in the language of State Property Systems, presupposes as an additional datum an orthocomplementation on the property lattice of a physical system. In this paper we argue on the basis of the ( ?, d)-model on the Poincaré sphere that a notion of topologicity for states can be seen as an alternative (operationally foundable) classicality notion in the absence of an orthocomplementation, and compare it to the known and operationally founded concept of classicality.

Aerts, Diederik; D'Hooghe, Bart; Sioen, Mark

2011-12-01

473

Symmetry-protected topological states of interacting fermions and bosons

NASA Astrophysics Data System (ADS)

We study the classification for a large class of interacting fermionic and bosonic symmetry-protected topological (SPT) states, focusing on the cases where interaction reduces the classification of free-fermion SPT states. We define a SPT state as whether it is separated from the trivial state through a bulk phase transition, which is a general definition applicable to SPT states with or without spatial symmetries. We show that in all dimensions short-range interactions can reduce the classification of free-fermion SPT states, and we demonstrate these results by making a connection between the fermionic and bosonic SPT states. We first demonstrate that our formalism gives the correct classification for several known SPT states, with or without interaction, and then we generalize our method to SPT states that involve the spatial inversion symmetry.

You, Yi-Zhuang; Xu, Cenke

2014-12-01

474

The U(1) Topological Gauge Field Theory for Topological Defects in Liquid Crystals

A novel U(1) topological gauge field theory for topological defects in liquid crystals is constructed by considering the U(1) gauge field is invariant under the director inversion. Via the U(1) gauge potential decomposition theory and the $\\\\phi$-mapping topological current theory, the decomposition expression of U(1) gauge field and the unified topological current for monopoles and strings in liquid crystals are

Yi-shi Duan; Li Zhao; Xin-hui Zhang; Tie-yan Si

2005-01-01

475

Uranyl peroxide closed clusters containing topological squares

Four self-assembling clusters of uranyl peroxide polyhedra have been formed in alkaline aqueous solutions and structurally characterized. These clusters consist of 28, 30, 36 and 44 uranyl polyhedra and exhibit complex new topologies. Each has a structure that contains topological squares, pentagons and hexagons. Analysis of possible topologies within boundary constraints indicates a tendency for adoption of higher symmetry topologies in these cases. Small angle X-ray scattering data demonstrated that crystals of one of these clusters can be dissolved in ultrapure water and that the clusters remain intact for at least several days.

Unruh, Daniel K.; Burtner, Alicia; Pressprich, Laura; Sigmon, Ginger E.; Burns, Peter C.

2010-01-01

476

Magnetic topology of emerging flux regions

NASA Astrophysics Data System (ADS)

Coronal magnetic fields structure and governs the dynamics of the solar atmosphere. These magnetic fields are often complex, composed of multiples domains of magnetic-field-lines connectivity. The topology of the magnetic field allows a synthetic description of these complex magnetic field by highlighting the structural elements that are important for the dynamic and the activity of the corona. Topology identifies the key elements where magnetic reconnection will preferentially occurs, and allows to explain and predict the evolution of the coronal plasma. However the topological elements - such as null points, separatrices, separators - do not appear out of thin air. Along with energy, and helicity, the magnetic topology of an active region is build up as the consequence of flux emergence. Some topological elements, such as bald-patches, are even fully part of the mechanism of flux emergence mechanism and drive the evolution and the structuration of the coronal magnetic field as it crosses the lower layer of the solar atmosphere. In the present talk I will therefore review our current understanding of the formation of active region in terms of magnetic topology. I will speak on how the topological structures which are key to solar activity are formed. Meanwhile I'll also discus the topological properties of emerging active region and how topology influences the very process of flux emergence.

Pariat, Etienne

477

Proximity effects in topological insulator heterostructures

NASA Astrophysics Data System (ADS)

Topological insulators (TIs) are bulk insulators that possess robust helical conducting states along their interfaces with conventional insulators. A tremendous research effort has recently been devoted to Tl-based heterostructures, in which conventional proximity effects give rise to a series of exotic physical phenomena. This paper reviews our recent studies on the potential existence of topological proximity effects at the interface between a topological insulator and a normal insulator or other topologically trivial systems. Using first-principles approaches, we have realized the tunability of the vertical location of the topological helical state via intriguing dual-proximity effects. To further elucidate the control parameters of this effect, we have used the graphene-based heterostructures as prototypical systems to reveal a more complete phase diagram. On the application side of the topological helical states, we have presented a catalysis example, where the topological helical state plays an essential role in facilitating surface reactions by serving as an effective electron bath. These discoveries lay the foundation for accurate manipulation of the real space properties of the topological helical state in TI-based heterostructures and pave the way for realization of the salient functionality of topological insulators in future device applications.

Li, Xiao-Guang; Zhang, Gu-Feng; Wu, Guang-Fen; Chen, Hua; Dimitrie, Culcer; Zhang, Zhen-Yu

2013-09-01

478

Magnetic topological insulators at finite temperature.

In this paper, we study the two-dimensional magnetic topological insulators from the correlated Chern insulator and the correlated Z2 topological insulator at finite temperature. For the 2D correlated Chern insulator, we find that the thermal-fluctuation-induced magnetic topological insulator (MTI) appears in the intermediate interaction region of the correlated Chern insulator. On the contrary, for the correlated Z2 topological insulator, thermal-fluctuation-induced MTI does not exist. Finally, we offer an explanation on the difference between the two cases. PMID:24722555

Zhu, Y-X; He, J; Zang, C-L; Liang, Y; Kou, S-P

2014-04-30

479

Charged particle in higher dimensional weakly charged rotating black hole spacetime

We study charged particle motion in weakly charged higher dimensional black holes. To describe the electromagnetic field we use a test field approximation and the higher dimensional Kerr-NUT-(A)dS metric as a background geometry. It is shown that for a special configuration of the electromagnetic field, the equations of motion of charged particles are completely integrable. The vector potential of such a field is proportional to one of the Killing vectors (called a primary Killing vector) from the 'Killing tower' of symmetry generating objects which exists in the background geometry. A free constant in the definition of the adopted electromagnetic potential is proportional to the electric charge of the higher dimensional black hole. The full set of independent conserved quantities in involution is found. We demonstrate that Hamilton-Jacobi equations are separable, as is the corresponding Klein-Gordon equation and its symmetry operators.

Frolov, Valeri P.; Krtous, Pavel [Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, T6G 2G7 (Canada); Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University in Prague, V Holesovickach 2, Prague (Czech Republic)

2011-01-15

480

Topological issues in hexahedral meshing D. Eppstein, UC Irvine, ATMCS 2001 Topological Issues;Topological issues in hexahedral meshing D. Eppstein, UC Irvine, ATMCS 2001 Outline I. What is meshing in hexahedral meshing D. Eppstein, UC Irvine, ATMCS 2001 I. What is Meshing? Given an input domain (manifold

Eppstein, David

481

topological structure of the bulk energy bands, and impose further constraints on the surface band structureSurface states and topological invariants in three-dimensional topological insulators: Application Brillouin zone. This confirms that the alloy is a strong topological insulator in the 1;111 Z2 topological

Kane, Charles

482

Charge density waves in a relaxation semiconductor

NASA Astrophysics Data System (ADS)

The response of a relaxation inhomogeneous semiconductor (specimen with an injecting contact and/or an inversion layer) containing an impurity with positive correlation energy, to a sudden increase in the electrical field and/or bias lighting is investigated. Under definite conditions the charge-carrier plasma turns out to be unstable relative to charge density wave excitation; their frequencies and damping decrements are found. Under the influence of waves of spatial overcharging of centers with positive correlation energy an increase is possible in the imaginary part of the impedance, as is the appearance of an oscillating frequency dependence of the imaginary and real parts of the impedance. The time dependence of the response is examined, and both exponential and power-law damping is possible depending on the kind of charge carrier forming the wave.

Drozhzhov, Yu. P.

1987-06-01

483

The formation of topological defects in phase transitions

NASA Technical Reports Server (NTRS)

It was argued, and fought through numerical work that the results of non-dynamical Monte Carlo computer simulations cannot be applied to describe the formation of topological defects when the correlation length at the Ginzburg temperature is significantly smaller than the horizon size. To test the current hypothesis that infinite strings at formation are essentially described by Brownian walks of size the correlation length at the Ginzburg temperature, fields at the Ginzburg temperature were equilibrated. Infinite structure do not exist in equilibrium for reasonable definitions of the Ginzburg temperature, and horizons must be included in a proper treatment. A phase transition, from small-scale to large-scale string or domain wall structure, is found to occur very close to the Ginzburg temperature, in agreement with recent work. The formation process of domain walls and global strings were investigated through the breaking of initially ordered states. To mimic conditions in the early Universe, cooling times are chosen so that horizons exist in the sample volume when topological structure formation occurs. The classical fields are evolved in real-time by the numerical solution of Langevin equations of motion on a three dimensional spatial lattice. The results indicate that it is possible for most of the string energy to be in small loops, rather than in long strings, at formation.