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1

Irrational charge from topological order  

E-print Network

Topological or deconfined phases of matter exhibit emergent gauge fields and quasiparticles that carry a corresponding gauge charge. In systems with an intrinsic conserved U(1) charge, such as all electronic systems where the Coulombic charge plays this role, these quasiparticles are also characterized by their intrinsic charge. We show that one can take advantage of the topological order fairly generally to produce periodic Hamiltonians which endow the quasiparticles with continuously variable, generically irrational, intrinsic charges. Examples include various topologically ordered lattice models, the three dimensional RVB liquid on bipartite lattices as well as water and spin ice. By contrast, the gauge charges of the quasiparticles retain their quantized values.

R. Moessner; S. L. Sondhi

2010-04-13

2

Composite Multihump Vector Solitons Carrying Topological Charge  

Microsoft Academic Search

We propose composite solitons carrying topological charge: multicomponent two dimensional [ \\\\(2+1\\\\)D] vector (Manakov-like) solitons for which at least one component carries topological charge. These multimode solitons can have a single hump or exhibit a multihump structure. The ``spin'' carried by these multimode composite solitons suggests 3D soliton interactions in which the particlelike behavior includes spin, in addition to effective

Ziad H. Musslimani; Mordechai Segev; Demetrios N. Christodoulides; Marin SoljaciC

2000-01-01

3

Health Insurance Definitions Allowable Charge  

E-print Network

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

4

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

E-print Network

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

5

Topology-based Feature Definition and Analysis  

SciTech Connect

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

6

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

E-print Network

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

7

Section 16 The Subspace Topology. Definition: Let X be a topological space with topology T . If Y is a subset of X, then the  

E-print Network

Section 16 The Subspace Topology. Definition: Let X be a topological space with topology T . If Y is a subset of X, then the collection ! T Y = Y "U |U # T{ } is a topology on Y. This topology is called the subspace topology. Lemma 16.1: If B is a basis for the topology of X, then the collection ! BY = Y " B | B

Scannell, Kevin Patrick

8

Topological charge pumping in a one-dimensional optical lattice.  

PubMed

A topological charge pump transfers charge in a quantized fashion. The quantization is stable against the detailed form of the pumping protocols and external noises and shares the same topological origin as the quantum Hall effect. We propose an experimental setup to realize topological charge pumping of cold fermionic atoms in a one-dimensional optical lattice. The quantization of the pumped charge is confirmed by first-principles simulations of the dynamics of uniform and trapped systems. Quantum effects are shown to be crucial for the topological protection of the charge quantization. Finite-temperature and nonadiabatic effects on the experimental observables are discussed. The realization of such a topological charge pump serves as a firm step toward exploring topological states and nonequilibrium dynamics using cold atoms. PMID:23889428

Wang, Lei; Troyer, Matthias; Dai, Xi

2013-07-12

9

Light-controlled topological charge in a nematic liquid crystal  

NASA Astrophysics Data System (ADS)

Creating, imaging, and transforming the topological charge in a superconductor, a superfluid, a system of cold atoms, or a soft ferromagnet is a difficult--if not impossible--task because of the shortness of the length scales and lack of control. The length scale and softness of defects in liquid crystals allow the easy observation of charges, but it is difficult to control charge creation. Here we demonstrate full control over the creation, manipulation and analysis of topological charges that are pinned to a microfibre in a nematic liquid crystal. Oppositely charged pairs are created through the Kibble-Zurek mechanism by applying a laser-induced local temperature quench in the presence of symmetry-breaking boundaries. The pairs are long-lived, oppositely charged rings or points that either attract and annihilate, or form a long-lived, charge-neutral loop made of two segments with a fractional topological charge.

Nikkhou, Maryam; Škarabot, Miha; ?opar, Simon; Ravnik, Miha; Žumer, Slobodan; Muševi?, Igor

2015-02-01

10

Effect of topology on the critical charge in graphene  

E-print Network

We show that the critical charge for the Dirac excitations in gapless graphene depends on the spatial topology of the sample. In particular, for graphene cones, the effective value of the critical charge can tend towards zero for a suitable angle of the conical sample. We discuss the nature of the scattering phase shifts, quasi-bound state energies and local density of states for a gapless graphene cone and determine the dependence of these physical quantities on the sample topology.

Baishali Chakraborty; Kumar S. Gupta; Siddhartha Sen

2010-11-18

11

Effect of topology on the critical charge in graphene  

SciTech Connect

We show that the critical charge for the Dirac excitations in gapless graphene depends on the spatial topology of the sample. In particular, for graphene cones, the effective value of the critical charge can tend toward zero for a suitable angle of the conical sample. We discuss the nature of the scattering phase shifts, quasibound state energies, and local density of states for a gapless graphene cone and determine the dependence of these physical quantities on the sample topology.

Chakraborty, Baishali; Gupta, Kumar S. [Theory Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700064 (India); Sen, Siddhartha [CRANN School of Physics, Trinity College, Dublin 2 (Ireland)

2011-03-15

12

Topological BPS charges in 10- and 11-dimensional supergravity  

SciTech Connect

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

13

Topological phase transition and gate-controlled charge transfer in minimal topological-spin qubit circuit  

NASA Astrophysics Data System (ADS)

We propose a minimal topological-spin qubit circuit to investigate the non-Abelian rotations within the degenerate ground-state manifold, as well as the topological phase transition and charge transfer. From a quantum dot, the state of the Majorana system can be read out. Along with the splitting of the degenerate ground-state manifold of a topological qubit, a topological phase transition is observed, showing the existence of a Majorana fermion. By choosing the phase difference across the dots, the non-Abelian rotations and the required energetically degenerate state in the qubit can be achieved, which results in universal quantum computation. Moreover, on the basis of the measurement of the electron in quantum dots and topological qubit, this demonstrates that topologically protected tunnel braids between dots and MBSs are critical to non-Abelian rotations.

Wang, Zhen-Hua; Kuang, Xiao-Yu; Zhong, Ming-Min; Yang, Zai-Xiu; Li, Hui

2014-06-01

14

Diffusion of topological charge in lattice QCD simulations  

E-print Network

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.

Greg McGlynn; Robert D. Mawhinney

2014-06-17

15

Topological central charge from Berry curvature: gravitational anomalies in trial wavefunctions for topological phases  

E-print Network

We show that the topological central charge of a topological phase can be directly accessed from the ground-state wavefunctions for a system on a surface as a Berry curvature produced by adiabatic variation of the metric on the surface, at least up to addition of another topological invariant that arises in some cases. For trial wavefunctions that are given by conformal blocks (chiral correlation functions) in a conformal field theory (CFT), we carry out this calculation analytically, using the hypothesis of generalized screening. The topological central charge is found to be that of the underlying CFT used in the construction, as expected. The calculation makes use of the gravitational anomaly in the chiral CFT. It is also shown that the Hall conductivity can be obtained in an analogous way from the U($1$) gauge anomaly.

Bradlyn, Barry

2015-01-01

16

Role of topological charge stabilization in protomeric tautomerism.  

PubMed

Protomeric tautomerism is analyzed in view of the topological charge stabilization rules. Based on Hückel molecular orbital considerations and modern DFT calculations, it was found that the branching of amino or hydroxyl groups significantly contributes to the stability of major species through the first- and second-order perturbations with respect to the isoelectronic hydrocarbon. While amino-imino tautomerism is almost completely dominated by topological charge stabilization, hydroxyl-oxo tautomerism is affected by changes in the resonance integral of C-O/C?O bonds. Nevertheless, apart from side effects such as hydrogen bonds or solvent effects, a quantitative preference rule for the prediction of the tautomeric stability can be developed using topological ?-electron energetics. As well as the analyses of simple bases, applications to complex or extended systems are exemplified analyzing purine bases, polyguanide, and polyuret. The present approach can be useful in conjunction with chemical intuition that comes from conventional valence bond theory. PMID:25619937

Hatanaka, Masashi

2015-02-12

17

Topological Charge Membranes in 2D and 4D Gauge Theory  

E-print Network

Local topological charge structure in the 2D CP(N-1) sigma models is studied using the overlap Dirac operator. Long-range coherence of topological charge along locally 1D regions in 2D space-time is observed. We discuss the connection between these results and the recent discovery of coherent 3D sheets of topological charge in 4D QCD. In both cases, coherent regions of topological charge form along surfaces of approximmate codimension 1.

H. Thacker; S. Ahmad; J. Lenaghan

2004-09-14

18

Topological defects in mixtures of superconducting condensates with different charges  

NASA Astrophysics Data System (ADS)

We investigate the topological defects in phenomenological models describing mixtures of charged condensates with commensurate electric charges. Such situations are expected to appear for example in liquid metallic deuterium. This is modeled by a multicomponent Ginzburg-Landau theory where the condensates are coupled to the same gauge field by different coupling constants whose ratio is a rational number. We also briefly discuss the case where electric charges are incommensurate. Flux quantization and finiteness of the energy per unit length dictate that the different condensates have different winding and thus different number of (fractional) vortices. Competing attractive and repulsive interactions lead to molecule-like bound states between fractional vortices. Such bound states have finite energy and carry integer flux quanta. These can be characterized by the CP1 topological invariant that motivates their denomination as skyrmions.

Garaud, Julien; Babaev, Egor

2014-06-01

19

Principal bundles and topological quantization of charges  

Microsoft Academic Search

The space of admissible particle velocities is assumed to be a four-dimensional nonholonomic distribution on a principal or\\u000a associated bundle. Equations for the horizontal geodesics of this distribution coincide with the equations of motion of charged\\u000a particles in general relativity theory. It is proved that, if the Lie group of the standard model of elementary particle physics\\u000a is augmented by

V. R. Krym; N. N. Petrov

2009-01-01

20

Characterization of topological charge and orbital angular momentum of shaped optical vortices.  

PubMed

Optical vortices (OV) are usually associated to cylindrically symmetric light beams. However, they can have more general geometries that extends their applicability. Since the typical experimental characterization methods are not appropriate for OV with arbitrary shapes, we discuss in this work how the definitions of the classical orbital angular momentum and the topological charge can be used to retrieve these informations in the general case. The concepts discussed are experimentally demonstrated and may be specially useful in areas such as optical tweezers and plasmonics. PMID:25606960

Amaral, Anderson M; Falcão-Filho, Edilson L; de Araújo, Cid B

2014-12-01

21

Wilson mass dependence of the overlap topological charge density  

NASA Astrophysics Data System (ADS)

The dependence of the overlap Dirac operator on the Wilson-mass regulator parameter is studied through calculations of the overlap topological charge densities at a variety of Wilson-mass values, using a Lüscher-Weisz gauge action. In this formulation, the Wilson-mass is used in the negative mass region and acts as a regulator governing the scale at which the Dirac operator is sensitive to topological aspects of the gauge field. We observe a clear dependence on the value of the Wilson-mass and demonstrate how these values can be calibrated against a finite number of stout-link smearing sweeps. The overlap topological charge density is also computed using a pre-smeared gauge field for the input kernel. We show how applying the overlap operator leads to further filtering of the gauge field. The results suggest that the freedom typically associated with smearing algorithms, through the variable number of sweeps, also exists in the overlap operator, through the variable Wilson-mass parameter.

Moran, Peter J.; Leinweber, Derek B.; Zhang, J. B.

2011-01-01

22

Charged-impurity-induced Majorana fermions in topological superconductors  

NASA Astrophysics Data System (ADS)

We study numerically Majorana fermions (MFs) induced by a charged impurity in topological superconductors. It is revealed from the relevant Bogoliubov-de Gennes equations that (i) for quasi-one-dimensional systems, a pair of MFs are bounded at the two sides of one charged impurity and are well-separated; and (ii) for a two-dimensional square lattice, the charged-impurity-induced MFs are similar to the known pair of vortex-induced MFs, in which one MF is bounded by the impurity while the other appears at the boundary. Moreover, the corresponding local density of states is explored, demonstrating that the presence of MF states may be tested experimentally.

Zhou, Tao; Li, Xiao-Jing; Gao, Yi; Wang, Z. D.

2015-01-01

23

Simultaneous magnetic and charge doping of topological insulators with carbon.  

PubMed

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 (C(Se)) 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 C(Se) 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 C(Se). This dual function of carbon doping suggests a simple way to realize insulating massive TSS. PMID:24476296

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

2013-12-01

24

C library for topological study of the electronic charge density.  

PubMed

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

25

Topological Charge Pumping in a One-Dimensional Optical Lattice Lei Wang,1,2  

E-print Network

Topological Charge Pumping in a One-Dimensional Optical Lattice Lei Wang,1,2 Matthias Troyer,1 (Received 30 January 2013; published 9 July 2013) A topological charge pump transfers charge in a quantized fashion. The quantization is stable against the detailed form of the pumping protocols and external noises

Wang, Wei Hua

26

Optical phased array radiating optical vortex with manipulated topological charges.  

PubMed

Optical antennas are key elements in quantum optics emitting and sensing, and behave wide range applications in optical domain. However, integration of optical antenna radiating orbital angular momentum is still a challenge in nano-scale. We theoretically demonstrate a sub-wavelength phased optical antenna array, which manipulates the distribution of the orbital angular momentum in the near field. Orbital angular momentum with topological charge of 4 can be obtained by controlling the phase distribution of the fundamental mode orbital angular momentum in each antenna element. Our results indicate this phased array may be utilized in high integrated optical communication systems. PMID:25836522

Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Luo, Xiangang

2015-02-23

27

Propagation of optical vortices with fractional topological charge in free space  

NASA Astrophysics Data System (ADS)

The behavior of the optical vortices with fractional topological charges in the far-field is assessed through numerical modeling and confirmed by experimental results. The generation of fractional topological charge variations of the phase within a Gaussian beam was achieved by using a liquid crystal spatial light modulator (LCoS SLM). It is shown that a laser beam carrying an optical vortex with a fractional topological charge evolves into a beam with a topological charge of integer value, specifically an integer value closer to the fractional number in the far field. A potential application of this work is for data transmission within optical telecommunication systems.

Ali, Tamelia; Kreminska, Liubov; Golovin, Andrii B.; Crouse, David T.

2014-10-01

28

Classical and Quantum Mechanics of Dirac-like Topological Charges in Yang-Mills Fields  

Microsoft Academic Search

Most nonabelian gauge theories admit the existence of conserved and quantized topological charges as generalizations of the Dirac monopole. Their interactions are dictated by topology. In this paper, previous work in deriving classical equations of motion for these charges is extended to quantized particles described by Dirac wave functions. The resulting equations show intriguing similarities to the Yang-Mills theory. Further,

Chan Hong-Mo; J. Faridani; Tsou Sheung Tsun

1993-01-01

29

Theoretical and experimental study of the topological charge of linear and nonlinear acoustical vortices  

NASA Astrophysics Data System (ADS)

An acoustical or optical vortex is a beam whose phase is winding along a line of phase singularity. The intensity associated to such a beam, also called screw dislocation, has a doughnught shape. The number of 2? jumps of the phase around the singularity line is called the topological charge. Using the concept of pseudo-momentum, a general relation linking the pseudo-energy, the angular pseudo-momentum and the topological charge of an acoustical vortex is derived. In an inviscid and isotropic medium, this relation can be interpreted as a conservation law of the topological charge for linear vortices, while it implies a linear increase of the topological charge with the order of harmonics for nonlinear vortices. These behaviors of the topological charge have been experimentally confirmed for linear and nonlinear acoustical vortices. Experimental results obtained by a new and versatile experimental set-up will be presented.

Marchiano, R.; Thomas, J.-L.

2006-05-01

30

Charged skyrmions on the surface of a topological insulator  

NASA Astrophysics Data System (ADS)

We consider the interplay between magnetic skyrmions in an insulating thin film and the Dirac surface states of a three-dimensional topological insulator (TI), coupled by the proximity effect. The magnetic texture of skyrmions can lead to confinement of Dirac states at the skyrmion radius, where out-of-plane magnetization vanishes. This confinement can result in charging of the skyrmion texture. The presence of bound states is robust in an external magnetic field, which is needed to stabilize skyrmions. It is expected that, for relevant experimental parameters, skyrmions will have a few bound states that can be tuned using an external magnetic field. We argue that these charged skyrmions can be manipulated directly by an electric field, with skyrmion mobility proportional to the number of bound states at the skyrmion radius. Coupling skyrmionic thin films to a TI surface can provide a more direct and efficient way of controlling skyrmion motion in insulating materials. This provides a different dimension in the study of skyrmion manipulation.

Hurst, Hilary M.; Efimkin, Dmitry K.; Zang, Jiadong; Galitski, Victor

2015-02-01

31

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

E-print Network

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

32

Coherent Topological Charge Structure in $CP^{N-1}$ Models and QCD  

E-print Network

In an effort to clarify the significance of the recent observation of long-range topological charge coherence in QCD gauge configurations, we study the local topological charge distributions in two-dimensional $CP^{N-1}$ sigma models, using the overlap Dirac operator to construct the lattice topological charge. We find long-range sign coherence of topological charge along extended one-dimensional structures in two-dimensional spacetime. We discuss the connection between the long range topological structure found in $CP^{N-1}$ and the observed sign coherence along three-dimensional sheets in four-dimensional QCD gauge configurations. In both cases, coherent regions of topological charge form along membrane-like surfaces of codimension one. We show that the Monte Carlo results, for both two-dimensional and four-dimensional gauge theory, support a view of topological charge fluctuations suggested by Luscher and Witten. In this framework, the observed membranes are associated with boundaries between ``k-vacua,'' characterized by an effective local value of $\\theta$ which jumps by $\\pm 2\\pi$ across the boundary.

Saeed Ahmad; Jonathan T. Lenaghan; H. B. Thacker

2005-09-21

33

Probing the topological charge of a vortex beam with dynamic angular double slits  

NASA Astrophysics Data System (ADS)

When a vortex beam with the spiral phase structure passes through a dynamic angular double slits (ADS), the interference pattern changes alternatively between destructive and constructive at the angular bisector direction of the ADS due to their phase difference. Based on this property, we experimentally demonstrate a simple method, which can precisely and efficiently determine the topological charge of vortex beams. What is more, this scheme allows determining both the modulus and sign of the topological charge of vortex beams simultaneously.

Fu, Dongzhi; Chen, Dongxu; Liu, Ruifeng; Wang, Yunlong; Gao, Hong; Li, Fuli; Zhang, Pei

2015-03-01

34

Topological Effects of Charge Transfer in Telomere G-Quadruplex Mechanism on Telomerase Activation and Inhibition  

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

35

Charge and spin fractionalization in strongly correlated topological insulators.  

PubMed

We construct an effective topological Landau-Ginzburg theory that describes general SU(2) incompressible quantum liquids of strongly correlated particles in two spatial dimensions. This theory characterizes the fractionalization of quasiparticle quantum numbers and statistics in relation to the topological ground-state symmetries, and generalizes the Chern-Simons, BF ('background field') and hierarchical effective gauge theories to an arbitrary representation of the SU(2) symmetry group. We mainly focus on fractional topological insulators with time-reversal symmetry, which are treated as SU(2) generalizations of the quantum Hall effect. PMID:23209083

Nikoli?, Predrag

2013-01-16

36

Topological charge quantization via path integration: An application of the Kustaanheimo-Stiefel transformation  

Microsoft Academic Search

The unified treatment of the Dirac monopole, the Schwinger monopole, and the Aharonov-Bohm problem by Barut and Wilson is revisited via a path integral approach. The Kustaanheimo-Stiefel transformation of space and time is utilized to calculate the path integral for a charged particle in the singular vector potential. In the process of dimensional reduction, a topological charge quantization rule is

Akira Inomata; Georg Junker; Raj Wilson

1993-01-01

37

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 high definition television (HDTV) imager chip operating at a frame rate of about 170 frames/sec at 2 Megapixels per frame. This imager offers an order of magnitude improvement in speed over CCD designs and will allow for monolithic imagers operating from the IR to the UV. The technical approach of the project focuses on the development of the three basic components of the imager and their integration. The imager chip can be divided into three distinct components: (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 development of manufacturable designs for each of these component devices. In addition to the development of each of the three distinct components, work towards their integration 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 in Sections 2-4.

Hunt, W. D.; Brennan, Kevin F.

1994-01-01

38

Topological Insulator Magnetic Tunnel Junctions: Quantum Hall Effect and Fractional Charge via Folding  

NASA Astrophysics Data System (ADS)

We provide a characterization of tunneling between coupled topological insulators in 2D and 3D under the influence of a ferromagnetic layer. We explore conditions for such systems to exhibit integer quantum Hall physics and localized fractional charge, also taking into account interaction effects for the 2D case. We show that the effects of tunneling are topologically equivalent to a certain deformation or folding of the sample geometry. Our key advance is the realization that the quantum Hall or fractional charge physics can appear in the presence of only a single magnet unlike previous proposals which involve magnetic domain walls on the surface or edges of topological insulators, respectively. We give illustrative topological folding arguments to prove our results and show that for the 2D case our results are robust even in the presence of interactions.

Meng, Qinglei; Vishveshwara, Smitha; Hughes, Taylor L.

2012-10-01

39

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

40

Polarization pattern of vector vortex beams generated by $q$-plates with different topological charges  

E-print Network

We describe the polarization topology of the vector beams emerging from a patterned birefringent liquid crystal plate with a topological charge $q$ at its center ($q$-plate). The polarization topological structures for different $q$-plates and different input polarization states have been studied experimentally by measuring the Stokes parameters point-by-point in the beam transverse plane. Furthermore, we used a tuned $q=1/2$-plate to generate cylindrical vector beams with radial or azimuthal polarizations, with the possibility of switching dynamically between these two cases by simply changing the linear polarization of the input beam.

Cardano, Filippo; Slussarenko, Sergei; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

2012-01-01

41

Fractional quantization of the topological charge pumping in a one-dimensional superlattice  

NASA Astrophysics Data System (ADS)

A one-dimensional quantum charge pump transfers a quantized charge in each pumping cycle. This quantization is topologically robust, being analogous to the quantum Hall effect. The charge transferred in a fraction of the pumping period is instead generally unquantized. We show, however, that with specific symmetries in parameter space the charge transferred at well-defined fractions of the pumping period is quantized as integer fractions of the Chern number. We illustrate this in a one-dimensional Harper-Hofstadter model and show that the fractional quantization of the topological charge pumping is independent of the specific boundary conditions taken into account. We further discuss the relevance of this phenomenon for cold atomic gases in optical superlattices.

Marra, Pasquale; Citro, Roberta; Ortix, Carmine

2015-03-01

42

Classical and quantum mechanics of Dirac-like topological charges in Yang-Mills fields  

E-print Network

Most nonabelian gauge theories admit the existence of conserved and quantized topological charges as generalizations of the Dirac monopole. Their interactions are dictated by topology. In this paper, previous work in deriving classical equations of motion for these charges is extended to quantized particles described by Dirac wave functions. The resulting equations show intriguing similarities to the Yang-Mills theory. Further, although the system is not dual symmetric, its gauge symmetry is nevertheless doubled as in the abelian case from $G$ to $G \\times G$, where the second $G$ has opposite parity to the first but is mediated instead by an antisymmetric second-rank tensor potential. (hep-th/yymmnnn)

Hong-Mo, C; Tsun, T S; Chan Hong-Mo; Tsou Sheung Tsun

1995-01-01

43

Classical and Quantum Mechanics of Dirac-like Topological Charges in Yang-Mills Fields  

E-print Network

Most nonabelian gauge theories admit the existence of conserved and quantized topological charges as generalizations of the Dirac monopole. Their interactions are dictated by topology. In this paper, previous work in deriving classical equations of motion for these charges is extended to quantized particles described by Dirac wave functions. The resulting equations show intriguing similarities to the Yang-Mills theory. Further, although the system is not dual symmetric, its gauge symmetry is nevertheless doubled as in the abelian case from $G$ to $G \\times G$, where the second $G$ has opposite parity to the first but is mediated instead by an antisymmetric second-rank tensor potential. (hep-th/yymmnnn)

Chan Hong-Mo; J. Faridani; Tsou Sheung Tsun

1993-12-09

44

Lifetime of charged and neutral B hadrons using event topology  

NASA Astrophysics Data System (ADS)

The lifetimes of charged and neutral B hadrons have been measured using data collected by the DELPHI experiment at LEP between 1991 and 1993. B hadrons are tagged as jets with a secondary vertex and the charge of the B candidate is taken to be the sum of the charges of the particles in the secondary vertex. Approximately 1,434,000 multihadronic Z0 decays yielded 1817 B hadron candidates. The B purity was estimated to be around 99.1±0.3%, and 83% (70%) of the events measured as neutral (charged) came from neutral (charged) B's. The mean lifetimes of charged and neutral B hadrons were found to be 1.72±0.08 (stat.) ±0.06 (syst.) ps and 1.58±0.11 (stat.)±0.09 (syst.) ps respectively. The ratio of their lifertimes, ?charged/?neutral, was 1.09{-0.10/+0.11} (stat.)±0.08 (syst.). By making assumptions about the B{s/0} and ?{b/0} states, the B+ and B0 meson lifetimes were determined to be ?B+ = 1.72 ± 0.08 (stat.) ±0.06 (syst.) ps and ?B+ = 1.63 ± 0.14 (stat.)±0.13 (syst.) ps and the ratio of their lifetimes was: ?B+/?B0 = 1.06{-0.11/+0.13} ±0.10. The mean B lifetime was also deduced to be < ? > = 1.64 ±0.06 (stat.)±0.04 (syst.) ps.

Adam, W.; Adye, T.; Agasi, E.; Ajinenko, I.; Aleksan, R.; Alekseev, G. D.; Allport, P. P.; Almehed, S.; Alvsvaag, S. J.; Amaldi, U.; Amato, S.; Andreazza, A.; Andrieux, M. L.; Antilogus, P.; Anykeyev, V.; Apel, W. D.; Arnoud, Y.; Åsman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Bambade, P.; Barao, F.; Barate, R.; Bardin, D. Y.; Barker, G. J.; Baroncelli, A.; Barring, O.; Barrio, J. A.; Bartl, W.; Bates, M. J.; Battaglia, M.; Baubillier, M.; Baudot, J.; Becks, K.-H.; Begalli, M.; Beilliere, P.; Belokopytov, Yu.; Benvenuti, A. C.; Berggren, M.; Bertrand, D.; Bianchi, F.; Bigi, M.; Bilenky, M. S.; Billoir, P.; Bloch, D.; Blume, M.; Blyth, S.; Bocci, V.; Bolognese, T.; Bonesini, M.; Bonivento, W.; Booth, P. S. L.; Borisov, G.; Bosio, C.; Bosworth, S.; Botner, O.; Bouquet, B.; Bourdarios, C.; Bowcock, T. J. V.; Bozzo, M.; Branchini, P.; Brand, K. D.; Brenner, R. A.; Bricman, C.; Brillault, L.; Brown, R. C. A.; Bruckman, P.; Brunet, J.-M.; Bugge, L.; Buran, T.; Buys, A.; Caccia, M.; Calvi, M.; Camacho Rozas, A. J.; Camporesi, T.; Canale, V.; Canepa, M.; Cankocak, K.; Cao, F.; Carena, F.; Carrilho, P.; Carroll, L.; Caso, C.; Castillo Gimenez, M. V.; Cattai, A.; Cavallo, F. R.; Cerrito, L.; Chabaud, V.; Charpentier, Ph.; Chaussard, L.; Chauveau, J.; Checchia, P.; Chelkov, G. A.; Chierici, R.; Chliapnikov, P.; Chochula, P.; Chorowicz, V.; Cindro, V.; Collins, P.; Contreras, J. L.; Contri, R.; Cortina, E.; Cosme, G.; Cossutti, F.; Crawley, H. B.; Crennell, D.; Crosetti, G.; Cuevas Maestro, J.; Czellar, S.; Dahl-Jensen, E.; Dahm, J.; Dalmagne, B.; Dam, M.; Damgaard, G.; Daum, A.; Dauncey, P. D.; Davenport, M.; da Silva, W.; Defoix, C.; Della Ricca, G.; Delpierre, P.; Demaria, N.; de Angelis, A.; de Boeck, H.; de Boer, W.; de Brabandere, S.; de Clercq, C.; de La Vaissiere, C.; de Lotto, B.; de Min, A.; de Paula, L.; de Saint-Jean, C.; Dijkstra, H.; di Ciaccio, L.; Djama, F.; Dolbeau, J.; Donszelmann, M.; Doroba, K.; Dracos, M.; Drees, J.; Drees, K. A.; Dris, M.; Dufour, Y.; Dupont, F.; Edsall, D.; Ehret, R.; Eigen, G.; Ekelof, T.; Ekspong, G.; Elsing, M.; Engel, J.-P.; Ershaidat, N.; Erzen, B.; Espirito Santo, M.; Falk, E.; Fassouliotis, D.; Feindt, M.; Ferrer, A.; Filippas, T. A.; Firestone, A.; Fischer, P. A.; Foeth, H.; Fokitis, E.; Fontanelli, F.; Formenti, F.; Franek, B.; Frenkiel, P.; Fries, D. C.; Frodesen, A. G.; Frhwirth, R.; Fulda-Quenzer, F.; Furstenau, H.; Fuster, J.; Galloni, A.; Gamba, D.; Gandelman, M.; Garcia, C.; Garcia, J.; Gaspar, C.; Gasparini, U.; Gavillet, Ph.; Gazis, E. N.; Gele, D.; Gerber, J.-P.; Gibbs, M.; Gillespie, D.; Gokieli, R.; Golob, B.; Gopal, G.; Gorn, L.; Gorski, M.; Gouz, Yu.; Gracco, V.; Graziani, E.; Grosdidier, G.; Gunnarsson, P.; Gunther, M.; Guy, J.; Haedinger, U.; Hahn, E.; Hahn, M.; Hahn, S.; Hajduk, Z.; Hallgren, A.; Hamacher, K.; Hao, W.; Harris, F. J.; Hedberg, V.; Henriques, R.; Hernandez, J. J.; Herquet, P.; Herr, H.; Hessing, T. L.; Higon, E.; Hilke, H. J.; Hill, T. S.; Holmgren, S.-O.; Holt, P. J.; Holthuizen, D.; Houlden, M.; Hrubec, J.; Huet, K.; Hultqvist, K.; Ioannou, P.; Jackson, J. N.; Jacobsson, R.; Jalocha, P.; Janik, R.; Jarlskog, G.; Jarry, P.; Jean-Marie, B.; Johansson, E. K.; Jonsson, L.; Jonsson, P.; Joram, C.; Juillot, P.; Kaiser, M.; Kalmus, G.; Kapusta, F.; Karlsson, M.; Karvelas, E.; Katsanevas, S.; Katsoufis, E. C.; Keranen, R.; Khomenko, B. A.; Khovanski, N. N.; King, B.; Kjaer, N. J.; Klein, H.; Klovning, A.; Kluit, P.; Koehne, J. H.; Koene, B.; Kokkinias, P.; Koratzinos, M.; Korcyl, K.; Kostioukhine, V.; Kourkoumelis, C.; Kouznetsov, O.; Kramer, P. H.; Krammer, M.; Kreuter, C.; Krolikowski, J.; Kronkvist, I.; Krumstein, Z.; Krupinski, W.; Kubinec, P.; Kucewicz, K.; Kurvinen, K.; Lacasta, C.; Laktineh, I.; Lamblot, S.; Lamsa, J. W.; Lanceri, L.; Lane, D. W.; Langefeld, P.; Lapin, V.; Last, I.; Laugier, J.-P.; Lauhakangas, R.; Leder, G.; Ledroit, F.; Lefebure, V.; Legan, C. K.; Leitner, R.; Lemoigne, Y.; Lemonne, J.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Liko, D.; Lindner, R.; Lipniacka, A.; Lippi, I.; Loerstad, B.; Lokajicek, M.; Loken, J. G.; Lopez, J. M.; Lopez-Fernandez, A.; Lopez Aguera, M. A.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Maehlum, G.; Maio, A.; Malychev, V.; Mandl, F.; Marco, J.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Maron, T.; Martinez-Rivero, C.; Martinez-Vidal, F.; Marti I Garcia, S.; Matorras, F.; Matteuzzi, C.; Matthiae, G.; Mazzucato, M.; Cubbin, M. Mc.; Kay, R. Mc; Nulty, R. Mc; Medbo, J.; Meroni, C.; Meyer, W. T.; Michelotto, M.; Migliore, E.; Mirabito, L.; Mitaroff, W. A.; Mjoernmark, U.; Moa, T.; Moeller, R.; Moenig, K.; Monge, M. R.; Morettini, P.; Mueller, H.; Mundim, L. M.; Murray, W. J.; Muryn, G.; Myatt, G.; Naraghi, F.; Navarria, F. L.; Navas, S.; Negri, P.

1995-09-01

45

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

46

Topological charge quantization via path integration: An application of the Kustaanheimo-Stiefel transformation  

SciTech Connect

The unified treatment of the Dirac monopole, the Schwinger monopole, and the Aharonov-Bahn problem by Barut and Wilson is revisited via a path integral approach. The Kustaanheimo-Stiefel transformation of space and time is utilized to calculate the path integral for a charged particle in the singular vector potential. In the process of dimensional reduction, a topological charge quantization rule is derived, which contains Dirac's quantization condition as a special case. 32 refs.

Inomata, A. (State Univ. of New York, Albany, NY (United States)); Junker, G. (Universitaet Erlangen-Nuernberg (Germany)); Wilson, R. (Univ. of Texas, San Antonio TX (United States))

1993-08-01

47

Computation of topological charges of optical vortices via nondegenerate four-wave mixing  

Microsoft Academic Search

In this paper, we report an experiment, which demonstrates computation of topological charges of two optical vortices via a nondegenerate four-wave-mixing process. We show that the output signal photon carries orbital angular momentum which equals to the subtraction of the orbital angular momenta of the probe light photon and the backward pump light photon. The Rb85 atoms are used as

Wei Jiang; Qun-Feng Chen; Yong-Sheng Zhang; G.-C. Guo

2006-01-01

48

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

49

Dumping topological charges on neighbors: ice manifolds for colloids and vortices  

NASA Astrophysics Data System (ADS)

We investigate the recently reported analogies between pinned vortices in nano-structured superconductors or colloids in optical traps, and spin ice materials. It has been found experimentally and numerically that both colloids and vortices exhibit ice or quasi-ice manifolds. However, the frustration of colloids and vortices differs essentially from spin ice at the vertex level. We show that the effective vertex energetics of the colloidal/vortex systems is made identical to that of spin ice materials by the contribution of an emergent field associated to the topological charge of the vertex. The similarity extends to the local low-energy dynamics of the ice manifold, where the effect of geometric hard constraints can be subsumed into the spatial modulation of the emergent field, which mediates an entropic interaction between topological charges. There, as in spin ice materials, genuine ice manifolds enter a Coulomb phase, whereas quasi-ice manifolds posses a well defined screening length, provided by a plasma of embedded topological charges. We also show that such similarities break down in lattices of mixed coordination because of topological charge transfer between sub-latices. This opens interesting perspective for extensions beyond physics, to social and economical networks.

Nisoli, Cristiano

2014-11-01

50

Charge topology of coherent dissociation of $^{11}$C and $^{12}$N relativistic nuclei  

E-print Network

The charge topology of the events of coherent dissociation of $^{11}$C and $^{12}$N of an energy of 1.2 A GeV in nuclear track emulsion is presented and its compared is given with the appropriate data on the nuclei $^{7}$Be, $^{8,10}$B, $^{9,10}$C and $^{14}$N.

D. A. Artemenkov; V. Bradnova; A. A. Zaitsev; P. I. Zarubin; I. G. Zarubina; R. R. Kattabekov; N. K. Kornegrutsa; K. Z. Mamatkulov; P. A. Rukoyatkin; V. V. Rusakova; R. Z. Stanoeva

2014-11-26

51

Charge quantisation without magnetic monopoles: a topological approach to electromagnetism  

E-print Network

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

52

Low dimensional long range topological charge structure in the QCD vacuum  

SciTech Connect

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

53

No P- V criticality for charged topological black holes in Ho?ava-Lifshitz gravity  

NASA Astrophysics Data System (ADS)

Searching for the unusual characteristics of Ho?ava-Lifshitz gravity, we generalize our former research of charged topological black holes in Ho?ava-Lifshitz gravity to the extended phase space. By treating cosmological constant as thermodynamic pressure, thermodynamic volume is derived as the conjugate quantity. P- V criticality is investigated by carrying out analytic analysis not only for the uncharged case but also for the charged case. All the topologies are considered. Unfortunately, no physical critical point has been found in all the cases. The results suggests again that the van der Waals like P- V criticality is not a universal phenomenon by providing one more example other than BTZ black holes. Our results also show that the existence of cosmological constant in the black hole metric is not sufficient for the existence of van der Waals like P- V criticality.

Mo, Jie-Xiong

2015-04-01

54

Vacuum periodicity in the instanton angle, chiral perturbation theory, and fractional topological charge  

SciTech Connect

Following Crewther, the methods of chiral perturbation theory and Dashen's theorem are applied to the QCD quark mass matrix. Stable domains of theta-vacua are found. The period of the system with respect to the instanton angle is 2..pi... It is concluded that non-integer topological charge is not required by chiral cymmetry breaking. An argument to the contrary by the present authors and by Crewther is refuted.

Palmer, W.F.; Pinsky, S.S.

1981-01-01

55

Determining the topological charge of stochastic electromagnetic vortex beams with the degree of cross-polarization.  

PubMed

By analysis of the degree of cross-polarization of a stochastic electromagnetic vortex beam, we find that the number of bright ring dislocations is equal to the topological charge of the vortex beam. Based on this property, we suggest a method to access the measurement of the orbital angular momentum of vector vortex beams, which holds true for cases of high coherence or low coherence. PMID:25166076

Luo, Meilan; Zhao, Daomu

2014-09-01

56

Computation of topological charges of optical vortices via nondegenerate four-wave mixing  

SciTech Connect

In this paper, we report an experiment, which demonstrates computation of topological charges of two optical vortices via a nondegenerate four-wave-mixing process. We show that the output signal photon carries orbital angular momentum which equals to the subtraction of the orbital angular momenta of the probe light photon and the backward pump light photon. The {sup 85}Rb atoms are used as the nonlinear medium, which transfers the orbital angular momenta of lights.

Jiang Wei; Chen Qunfeng; Zhang Yongsheng; Guo, G.-C. [Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026 (China)

2006-10-15

57

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

58

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

59

Direct observation of the topological charge of a terahertz vortex beam generated by a Tsurupica spiral phase plate  

SciTech Connect

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

60

Topology of the Spin-Polarized Charge Density in bcc and fcc Iron Travis E. Jones,1,* Mark E. Eberhart,1  

E-print Network

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 total spin-density is found to possess the topology of the non-magnetic prototypical structures

61

Topological aspects of charge-carrier transmission across grain boundaries in graphene.  

PubMed

Dislocations and grain boundaries are intrinsic topological defects of large-scale polycrystalline samples of graphene. These structural irregularities have been shown to strongly affect electronic transport in this material. Here, we report a systematic investigation of the transmission of charge carriers across the grain-boundary defects in polycrystalline graphene by means of the Landauer-Büttiker formalism within the tight-binding approximation. Calculations reveal a strong suppression of transmission at low energies upon decreasing the density of dislocations with the smallest Burgers vector b = (1,0). The observed transport anomaly is explained from the point of view of resonant backscattering due to localized states of topological origin. These states are related to the gauge field associated with all dislocations characterized by b = (n,m) with n - m ? 3q (q ? Z). Our work identifies an important source of charge-carrier scattering caused by the topological defects present in large-area graphene samples produced by chemical vapor deposition. PMID:24295423

Gargiulo, Fernando; Yazyev, Oleg V

2014-01-01

62

Topology  

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.

63

Quantum simulation of topological Majorana bound states and their universal quantum operations using charge-qubit arrays  

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

64

Topological effects of charge density waves in ring-shaped crystals of NbSe3  

Microsoft Academic Search

We studied the differences of the charge density wave (CDW) dynamics in closed-ring and open-ring topologies by measuring the frequency-dependent resistance in the radio-frequency range. We performed a two-probe ac resistance measurement for a ring-shaped crystal of niobium triselenide (NbSe3) in the 300kHzto1.3GHz frequency range. We compared the frequency dependence of the resistance of closed-ring and open-ring crystals and found

Toru Matsuura; Taku Tsuneta; Katsuhiko Inagaki; Satoshi Tanda

2006-01-01

65

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

66

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

SciTech Connect

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. [Department of Mathematical Sciences, University of Durham Science Laboratories, South Road, Durham DH1 3LE (United Kingdom)

2009-12-15

67

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

68

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

69

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

70

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

SciTech Connect

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

71

Phase fluctuations and the absence of topological defects in photo-excited charge ordered nickelate  

SciTech Connect

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 La1.75Sr0.25NiO4 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.; Denes, P.; Schlotter, W.F.; Turner, J.J.; Johnson, S.L.; F& #246; rst, M.; Sasagawa, T.; Kung, Y.F.; Sorini, A.P.; Kemper, A.F.; Moritz, B.; Devereaux, T.P.; Lee, D.-H.; Shen, Z.X.; Hussain, Z.

2012-01-01

72

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

73

Membranes with topological charge and AdS{sub 4}/CFT{sub 3} correspondence  

SciTech Connect

If the second Betti number b{sub 2} of a Sasaki-Einstein manifold Y{sup 7} does not vanish, then M-theory on AdS{sub 4}xY{sup 7} possesses 'topological' U(1){sup b}{sub 2} gauge symmetry. The corresponding Abelian gauge fields come from three-form fluctuations with one index in AdS{sub 4} and the other two in Y{sup 7}. We find black membrane solutions carrying one of these U(1) charges. In the zero-temperature limit, our solutions interpolate between AdS{sub 4}xY{sup 7} in the UV and AdS{sub 2}xR{sup 2}xsquashed Y{sup 7} in the IR. In fact, the AdS{sub 2}xR{sup 2}xsquashed Y{sup 7} background is by itself a solution of the supergravity equations of motion. These solutions do not appear to preserve any supersymmetry. We search for their possible instabilities and do not find any. We also discuss the meaning of our charged membrane backgrounds in a dual quiver Chern-Simons gauge theory with a global U(1) charge density. Finally, we present a simple analytic solution which has the same IR but different UV behavior. We reduce this solution to type IIA string theory, and perform T-duality to type IIB. The type IIB metric turns out to be a product of the squashed Y{sup 7} and the extremal Banados-Teitelboim-Zanelli black hole. We discuss an interpretation of this type IIB background in terms of the (1+1)-dimensional conformal field theory on D3-branes partially wrapped over the squashed Y{sup 7}.

Klebanov, Igor R. [Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544 (United States); Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544 (United States); Pufu, Silviu S.; Tesileanu, Tiberiu [Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544 (United States)

2010-06-15

74

Definition of the topological structure of the automatic control system of spacecrafts  

NASA Astrophysics Data System (ADS)

The paper considers the problem of selection the topological structure of the automated control system of spacecrafts. The integer linear model of mathematical programming designed to define the optimal topological structure for spacecraft control is proposed. To solve the determination problem of topological structure of the control system of spacecrafts developed the procedure of the directed search of some structure variants according to the scheme "Branch and bound". The example of the automated control system of spacecraft development included the combination of ground control stations, managing the spacecraft of three classes with a geosynchronous orbit with constant orbital periods is presented.

Zelenkov, P. V.; Karaseva, M. V.; Tsareva, E. A.; Tsarev, R. Y.

2015-01-01

75

Gel’fand-Yaglom equations with charge or energy density of definite sign  

Microsoft Academic Search

Summary  We consider finite-dimensional Gel’fand-Yaglom equations with the supplementary requirement that for half-odd spin the charge\\u000a density and for integer spin the energy density be positive definite. We derive, in general, a necessary condition to satisfy\\u000a this requirement, in terms of a restriction on the structure of the Gel’fand chains. For equations with unique mass and spin\\u000a this necessary condition is

V. Amar; U. Dozzio

1972-01-01

76

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

E-print Network

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

77

Topology of charge density and elastic properties of Ti3SiC2 polymorphs  

SciTech Connect

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

78

Flux-charge duality and topological quantum phase fluctuations in quasi-one-dimensional superconductors  

NASA Astrophysics Data System (ADS)

It has long been thought that macroscopic phase coherence breaks down in effectively lower-dimensional superconducting systems even at zero temperature due to enhanced topological quantum phase fluctuations. In quasi-one-dimensional wires, these fluctuations are described in terms of ‘quantum phase-slip’ (QPS): tunneling of the superconducting order parameter for the wire between states differing by ±2? in their relative phase between the wire's ends. Over the last several decades, many deviations from conventional bulk superconducting behavior have been observed in ultra-narrow superconducting nanowires, some of which have been identified with QPS. While at least some of the observations are consistent with existing theories for QPS, other observations in many cases point to contradictory conclusions or cannot be explained by these theories. Hence, our understanding of the nature of QPS, and its relationship to the various observations, has remained imcomplete. In this paper we present a new model for QPS which takes as its starting point an idea originally postulated by Mooij and Nazarov (2006 Nature Phys. 2 169): that flux-charge duality, a classical symmetry of Maxwell's equations, can be used to relate QPS to the well-known Josephson tunneling of Cooper pairs. Our model provides an alternative, and qualitatively different, conceptual basis for QPS and the phenomena which arise from it in experiments, and it appears to permit for the first time a unified understanding of observations across several different types of experiments and materials systems.

Kerman, Andrew J.

2013-10-01

79

Scalar and tensorial topological matter coupled to (2 + 1)-dimensional gravity: I. Classical theory and global charges  

NASA Astrophysics Data System (ADS)

We consider the coupling of scalar topological matter to (2 + 1)-dimensional gravity. The matter fields consist of a 0-form scalar field and a 2-form tensor field. We carry out a canonical analysis of the classical theory, investigating its sectors and solutions. We show that the model admits both BTZ-like black-hole solutions and homogeneous/inhomogeneous FRW cosmological solutions.We also investigate the global charges associated with the model and show that the algebra of charges is the extension of the Kac Moody algebra for the field-rigid gauge charges, and the Virasoro algebra for the diffeomorphism charges. Finally, we show that the model can be written as a generalized Chern Simons theory, opening the perspective for its formulation as a generalized higher gauge theory.

Mann, R. B.; Popescu, Eugeniu M.

2006-06-01

80

Fermi-level pinning, charge transfer, and relaxation of spin-momentum locking at metal contacts to topological insulators  

NASA Astrophysics Data System (ADS)

Topological insulators are of interest for many applications in electronics and optoelectronics, but harnessing their unique properties requires detailed understanding and control of charge injection at electrical contacts. Here we present large-scale ab initio calculations of the electronic properties of Au, Ni, Pt, Pd, and graphene contacts to Bi2Se3. We show that regardless of the metal, the Fermi level is located in the conduction band, leading to n-type Ohmic contact to the first quintuplet. Furthermore, we find strong charge transfer and band bending in the first few quintuplets, with no Schottky barrier for charge injection even when the topological insulator is undoped. Our calculations indicate that Au and graphene leave the spin-momentum locking mostly unaltered, but on the other hand, Ni, Pd, and Pt strongly hybridize with Bi2Se3 and relax spin-momentum locking. Our results indicate that judicious choice of the contact metal is essential to reveal the unique surface features of topological insulators.

Spataru, Catalin D.; Léonard, François

2014-08-01

81

Topological phases in iridium oxide superlattices: Quantized anomalous charge or valley Hall insulators  

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

82

Polarization pattern of vector vortex beams generated by q-plates with different topological charges  

E-print Network

Polarization pattern of vector vortex beams generated by q-plates with different topological angular momentum (OAM) [5]. Among vector vortex beams, radially or azimuthally polarized vec- tor beams; posted 3 January 2012 (Doc. ID 159438); published 5 March 2012 We describe the polarization topology

Marrucci, Lorenzo

83

Additive and multiplicative renormalization of topological charge with improved gluon/fermion actions: A test case for 3-loop vacuum calculations, using overlap or clover fermions  

E-print Network

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. Our work serves also as a test case of the techniques and limitations of lattice perturbation theory, it being the first 3-loop computation in the literature involving overlap fermions.

A. Skouroupathis; H. Panagopoulos

2006-01-02

84

Classical Tests of General Relativity: Probing Topologically Charged Black Holes on Brane Worlds in f(R) Bulk  

E-print Network

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

85

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

86

Multi-kink topological terms and charge-binding domain-wall condensation induced symmetry-protected topological states: Beyond Chern-Simons/BF theory  

E-print Network

Quantum-disordering a discrete-symmetry breaking state by condensing domain-walls can lead to a trivial symmetric insulator state. In this work, we show that if we bind a 1D representation of the symmetry (such as a charge) to the intersection point of several domain walls, condensing such modified domain-walls can lead to a non-trivial symmetry-protected topological (SPT) state. This result is obtained by showing that the modified domain-wall condensed state has a non-trivial SPT invariant -- the symmetry-twist dependent partition function. We propose two different kinds of field theories that can describe the above mentioned SPT states. The first one is a Ginzburg-Landau-type non-linear sigma model theory, but with an additional multi-kink domain-wall topological term. The second one is a gauge theory, which is beyond Abelian Chern Simons/BF gauge theories. We argue that the two field theories are equivalent at low energies. After coupling to the symmetry twists, both theories produce the desired SPT invariant. Our approach completely captures bosonic SPT states with finite Abelian group symmetry in 1+1D and 2+1D, and also sheds lights towards constructing complete bulk dynamical actions for Abelian bosonic SPT states in 3+1D. We further show that edge theories for these SPT states can be naturally derived from the bulk-edge correspondence via a dimension reduction scheme.

Zheng-Cheng Gu; Juven C. Wang; Xiao-Gang Wen

2015-03-05

87

Flux–charge duality and topological quantum phase fluctuations in quasi-one-dimensional superconductors  

E-print Network

It has long been thought that macroscopic phase coherence breaks down in effectively lower-dimensional superconducting systems even at zero temperature due to enhanced topological quantum phase fluctuations. In ...

Kerman, Andrew J.

88

Spin-to-charge conversion in lateral and vertical topological-insulator/ferromagnet heterostructures with microwave-driven precessing magnetization  

NASA Astrophysics Data System (ADS)

Using the charge-conserving Floquet-Green function approach to open quantum systems driven by an external time-periodic potential, we analyze how spin current pumped by the precessing magnetization of a ferromagnetic (F) layer is injected laterally into the interface with strong spin-orbit coupling (SOC) and converted into charge current flowing in the same direction. In the case of a metallic interface with the Rashba SOC used in recent experiments [J. C. R. Sánchez, L. Vila, G. Desfonds, S. Gambarelli, J. P. Attané, J. M. De Teresa, C. Magén, and A. Fert, Nat. Commun. 4, 2944 (2013), 10.1038/ncomms3944], both spin IS? and charge I current flow within the interface where I /IS?? 2-8% (depending on the precession cone angle), while for a F/topological-insulator (F/TI) interface employed in related experiments [Y. Shiomi, K. Nomura, Y. Kajiwara, K. Eto, M. Novak, K. Segawa, Y. Ando, and E. Saitoh, arXiv:1312.7091] the conversion efficiency is greatly enhanced (I /IS?? 40-60%) due to perfect spin-momentum locking on the surface of a TI. The spin-to-charge conversion occurs also when spin current is pumped vertically through the F/TI interface with smaller efficiency (I /IS?˜0.001%), but with the charge current signal being sensitive to whether the Dirac fermions at the interface are massive or massless.

Mahfouzi, Farzad; Nagaosa, Naoto; Nikoli?, Branislav K.

2014-09-01

89

A new topological aspect of the arbitrary dimensional topological defects  

Microsoft Academic Search

We present a new generalized topological current in terms of the order parameter field phi to describe the arbitrary dimensional topological defects. By virtue of the phi-mapping method, we show that the topological defects are generated from the zero points of the order parameter field phi, and the topological charges of these topological defects are topological quantized in terms of

Ying Jiang; Yishi Duan

2000-01-01

90

Topology and shape optimization of induced-charge electro-osmotic micropumps  

E-print Network

For a dielectric solid surrounded by an electrolyte and positioned inside an externally biased parallel-plate capacitor, we study numerically how the resulting induced-charge electro-osmotic (ICEO) flow depends on the ...

Gregersen, M. M.

91

Nonlinear cyclotron acceleration of massless Dirac charge carriers in graphene and topological insulators  

NASA Astrophysics Data System (ADS)

Two-dimensional motion of quasiparticles with the Dirac dispersion relation in an external magnetic field in the presence of electromagnetic radiation has been investigated. It has been shown that the mechanisms of acceleration in the phase-locked (autoresonance) regime known for classical charged particles can also take place for massless charge carriers. In this case, the energy distribution function of electrons exhibits a gap, the magnitude of which is governed by the magnetic field.

Tokman, M. D.; Erukhimova, M. A.; Belyanin, A.

2014-11-01

92

Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges  

E-print Network

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

93

Correlation and localization properties of topological charge density and the pseudoscalar glueball mass in lattice Yang-Mills theory  

E-print Network

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

94

Topological influence and backaction between topological excitations  

NASA Astrophysics Data System (ADS)

Topological objects can influence each other if the underlying homotopy groups are non-Abelian. Under such circumstances, the topological charge of each individual object is no longer a conserved quantity and can be transformed to each other. Yet we can identify the conservation law by considering the backaction of topological influence. We develop a general theory of topological influence and backaction based on the commutators of the underlying homotopy groups. In the case of the topological influence of a half-quantum vortex on a point defect, we point out that the topological backaction from the point defect is a twisting of the vortex. The total twist of the vortex line compensates for the change in the point-defect charge to conserve the total charge. We use this theory to classify charge transfers in condensed matter systems and show that a non-Abelian charge transfer can be realized in a spin-2 Bose-Einstein condensate.

Kobayashi, Shingo; Tarantino, Nicolas; Ueda, Masahito

2014-03-01

95

Topological black holes dressed with a conformally coupled scalar field and electric charge  

SciTech Connect

Electrically charged solutions for gravity with a conformally coupled scalar field are found in four dimensions in the presence of a cosmological constant. If a quartic self-interaction term for the scalar field is considered, there is a solution describing an asymptotically locally AdS charged black hole dressed with a scalar field that is regular on and outside the event horizon, which is a surface of negative constant curvature. This black hole can have negative mass, which is bounded from below for the extremal case, and its causal structure shows that the solution describes a ''black hole inside a black hole''. The thermodynamics of the nonextremal black hole is analyzed in the grand canonical ensemble. The entropy does not follow the area law, and there is an effective Newton constant which depends on the value of the scalar field at the horizon. If the base manifold is locally flat, the solution has no electric charge, and the scalar field has a vanishing stress-energy tensor so that it dresses a locally AdS spacetime with a nut at the origin. In the case of vanishing self interaction, the solutions also dress locally AdS spacetimes, and if the base manifold is of negative constant curvature a massless electrically charged hairy black hole is obtained. The thermodynamics of this black hole is also analyzed. It is found that the bounds for the black holes parameters in the conformal frame obtained from requiring the entropy to be positive are mapped into the ones that guarantee cosmic censorship in the Einstein frame.

Martinez, Cristian; Troncoso, Ricardo; Staforelli, Juan Pablo [Centro de Estudios Cientificos (CECS), Casilla 1469, Valdivia (Chile); Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Departamento de Fisica, P. Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Centro de Estudios Cientificos (CECS), Casilla 1469, Valdivia (Chile)

2006-08-15

96

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

97

Topological properties of hydrogen bonds and covalent bonds from charge densities obtained by the maximum entropy method (MEM)  

PubMed Central

Charge densities have been determined by the Maximum Entropy Method (MEM) from the high-resolution, low-temperature (T ? 20?K) X-ray diffraction data of six different crystals of amino acids and peptides. A comparison of dynamic deformation densities of the MEM with static and dynamic deformation densities of multipole models shows that the MEM may lead to a better description of the electron density in hydrogen bonds in cases where the multipole model has been restricted to isotropic displacement parameters and low-order multipoles (l max = 1) for the H atoms. Topological properties at bond critical points (BCPs) are found to depend systematically on the bond length, but with different functions for covalent C—C, C—N and C—O bonds, and for hydrogen bonds together with covalent C—H and N—H bonds. Similar dependencies are known for AIM properties derived from static multipole densities. The ratio of potential and kinetic energy densities |V(BCP)|/G(BCP) is successfully used for a classification of hydrogen bonds according to their distance d(H?O) between the H atom and the acceptor atom. The classification based on MEM densities coincides with the usual classification of hydrogen bonds as strong, intermediate and weak [Jeffrey (1997) ?. An Introduction to Hydrogen Bonding. Oxford University Press]. MEM and procrystal densities lead to similar values of the densities at the BCPs of hydrogen bonds, but differences are shown to prevail, such that it is found that only the true charge density, represented by MEM densities, the multipole model or some other method can lead to the correct characterization of chemical bonding. Our results do not confirm suggestions in the literature that the promolecule density might be sufficient for a characterization of hydrogen bonds. PMID:19767685

Netzel, Jeanette; van Smaalen, Sander

2009-01-01

98

Topological colloids.  

PubMed

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

99

Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges  

SciTech Connect

Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “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 orbital angular momentum ?. 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 traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ?=±2q? per photon. We experimentally demonstrate ? values ranging from ±1 to ±25 with conversion efficiencies of 8.6%?±?0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.

Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim, E-mail: ekarimi@uottawa.ca [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Boyd, Robert W. [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

2014-09-08

100

Charging Dirac states at antiphase domain boundaries in the three-dimensional topological insulator Bi2Se3.  

PubMed

Using scanning tunneling microscopy and transmission electron microscopy, we demonstrate the existence of antiphase boundaries between neighboring grains shifted by a fraction of a quintuple layer in epitaxial (0001) films of the three-dimensional topological insulator Bi(2)Se(3). Scanning tunneling spectroscopy and first-principles calculations reveal that these antiphase boundaries provide electrostatic fields on the order of 10(8) V/m that locally charge the Dirac states, modulating the carrier density, and shift the Dirac point by up to 120 meV. This intrinsic electric field effect, demonstrated here near interfaces between Bi(2)Se(3) grains, provides direct experimental evidence at the atomic scale that the Dirac states are indeed robust against extended structural defects and tunable by electric field. These results also shed light on the recent observation of coexistence of Dirac states and two-dimensional electron gas on Bi(2)Se(3) (0001) after adsorption of metal atoms and gas molecules. PMID:23683233

Liu, Y; Li, Y Y; Gilks, D; Lazarov, V K; Weinert, M; Li, L

2013-05-01

101

Signatures of charge inhomogeneities in the infrared spectra of topological insulators Bi2Se3, Bi2Te3 and Sb2Te3.  

PubMed

We present the results of an infrared spectroscopy study of topological insulators Bi(2)Se(3), Bi(2)Te(3) and Sb(2)Te(3). Reflectance spectra of all three materials look similar, with a well defined plasma edge. However, there are some important differences. Most notably, as temperature decreases the plasma edge shifts to lower frequencies in Bi(2)Se(3), whereas in Bi(2)Te(3) and Sb(2)Te(3) it shifts to higher frequencies. In the loss function spectra we identify asymmetric broadening of the plasmon, and assign it to the presence of charge inhomogeneities. It remains to be seen if charge inhomogeneities are characteristic of all topological insulators, and whether they are of intrinsic or extrinsic nature. PMID:23328626

Dordevic, S V; Wolf, M S; Stojilovic, N; Lei, Hechang; Petrovic, C

2013-02-20

102

A Survey of Computer Network Topology and Analysis Examples  

E-print Network

A Survey of Computer Network Topology and Analysis Examples Brett Meador, brett an introduction to Computer Network Topology. Definitions of Physical and Logical Topologies are provided. Additionally common Computer Network realizations of Physical Topologies are reviewed. This is followed

Jain, Raj

103

Topological quantization and cohomology  

Microsoft Academic Search

The relationships between topological charge quantization, Lagrangians and various cohomology theories are studied. A very general criterion for charge quantization is developed and applied to various physical models. The relationship between cohomology and homotopy is discussed.

Orlando Alvarez

1985-01-01

104

A topological theory of the Physical Vacuum  

E-print Network

This article examines how the physical presence of field energy and particulate matter could influence the topological properties of space time. The theory is developed in terms of vector and matrix equations of exterior differential forms. The topological features and the dynamics of such exterior differential systems are studied with respect to processes of continuous topological evolution. The theory starts from the sole postulate that field properties of a Physical Vacuum (a continuum) can be defined in terms of a vector space domain, of maximal rank, infinitesimal neighborhoods, that supports a Basis Frame as a 4 x 4 matrix of C2 functions with non-zero determinant. The basis vectors of such Basis Frames exhibit differential closure. The particle properties of the Physical Vacuum are defined in terms of topological defects (or compliments) of the field vector space defined by those points where the maximal rank, or non-zero determinant, condition fails. The topological universality of a Basis Frame over infinitesimal neighborhoods can be refined by particular choices of a subgroup structure of the Basis Frame, [B]. It is remarkable that from such a universal definition of a Physical Vacuum, specializations permit the deduction of the field structures of all four forces, from gravity fields to Yang Mills fields, and associate the origin of topological charge and topological spin to the Affine torsion coefficients of the induced Cartan Connection matrix [C] of 1-forms.

R. M. Kiehn

2006-03-01

105

Geometry and Topology  

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.

106

The Product Topology If X and Y are topological spaces, the product topology on X \\Theta Y is the topology generated by the  

E-print Network

6­23­1999 The Product Topology If X and Y are topological spaces, the product topology on X \\Theta Y is the topology generated by the basis consisting of all sets U \\Theta V , where U is open in X. How do you define a topology on a product of infinitely many spaces? Definition. Let fX a g a2A

Ikenaga, Bruce

107

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

108

A DFT study on the correlation between topology and Bader charges: Part I, effects of compression and expansion of As2O5  

NASA Astrophysics Data System (ADS)

Starting from known structures of the modifications of As2O5 we investigate the results of relaxations in DFT calculations performed at different fixed volumes per formula unit on keeping the axis relations and the symmetry of the original space group. We analyse the correlation between the topology of a structure, i.e. the co-ordination geometry and the distances observed, with the charges of the atoms as derived form a Bader analysis of the electron distribution resulting from a DFT relaxation. A similar study is done on the changes of the structure and the charges as a result of a relaxation without such a symmetry bias giving a new hitherto unknown possible high pressure structure.

Beck, Horst P.

2015-03-01

109

Nature of halogen bonding. A study based on the topological analysis of the Laplacian of the electron charge density and an energy decomposition analysis.  

PubMed

In this work we investigate the nature of the Cl···N interactions in complexes formed between substituted ammonium [NHn(X3-n) (with n?=?0, 1, 2, 3 and X?=?-CH3, -F] as Lewis bases and F-Cl molecule as Lewis acid. They have been chosen as a study case due to the wide range of variation of their binding energies, BEs. Møller-Plesset [MP2/6-311++G(2d,2p)] calculations show that the BEs for this set of complexes lie in the range from 1.27 kcal/mol (in F-Cl···NF3) to 27.62 kcal/mol [in F-Cl···N(CH3)3]. The intermolecular distribution of the electronic charge density and their L(r)?=?-¼?(2)?(r) function have been investigated within the framework of the atoms in molecules (AIM) theory. The intermolecular interaction energy decomposition has also been analyzed using the reduced variational space (RVS) method. The topological analysis of the L(r) function reveals that the local topological properties measured at the (3,+1) critical point [in L(r) topology] are good descriptors of the strength of the halogen bonding interactions. The results obtained from energy decomposition analysis indicate that electrostatic interactions play a key role in these halogen bonding interactions. These results allow us to establish that, when the halogen atom is bonded to a group with high electron-withdrawing capacity, the electrostatic interaction between the electron cloud of the Lewis base and the halogen atom unprotected nucleus of the Lewis acid produces the formation and determines the geometry of the halogen bonded complexes. In addition, a good linear relationship has been established between: the natural logarithm of the BEs and the electrostatic interaction energy between electron charge distribution of N atom and nucleus of Cl atom, denoted as V e-n(N,Cl) within the AIM theory. PMID:23076553

Duarte, Darío J R; Sosa, Gladis L; Peruchena, Nélida M

2013-05-01

110

Spanning set of silica cluster isomer topologies from QTAIM.  

PubMed

Structural and chemical properties of the building block of silica nanowires, (SiO(2))(6), are investigated with the theory of atoms and molecules (QTAIM). Twenty-five conformers have been analyzed, ten of which have not been reported before. We extend the silica (SiO(2))(6) topology phase space using QTAIM; the Poincaré-Hopf topological sum rules are applied and used to identify the spanning set of topologies, and this includes finding eight new distinct topologies that satisfy the Poincaré-Hopf relation. A simple phase diagram of the solutions of the Poincaré-Hopf relation is created with the aid of a new classification scheme to determine the boundary between topological stability and instability. Sum rules are then found to be applicable to any set of isomers. We determine that O-O bonding interactions exist for the silica (SiO(2))(6) conformers in regions where the energy surface is flattest. In addition, we identify unstable local minima in the topology of the charge density in order to further compare conformer instabilities. We quantify the dimensionality of a molecule using the Poincaré-Hopf relation instead of Euclidean geometry. This quantum topological definition of geometry shows that the four most energetically stable (SiO(2))(6) conformers are quantified as two-dimensional within the new quantum topology. PMID:21557588

Jenkins, Samantha; Rong, Chunying; Kirk, Steven R; Yin, Dulin; Liu, Shubin

2011-11-17

111

Topology in Ordered Phases  

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

112

Electrical detection of the spin polarization due to charge flow in the surface state of the topological insulator Bi(1.5)Sb(0.5)Te(1.7)Se(1.3).  

PubMed

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

113

Topological Quantization of the Magnetic Flux  

Microsoft Academic Search

The quantization of the magnetic flux in superconducting rings is studied in the frame of a topological model of electromagnetism that gives a topological formulation of electric charge quantization. It turns out that the model also embodies a topological mechanism for the quantization of the magnetic flux with the same relation between the fundamental units of magnetic charge and flux

Antonio F. Rañada; José Luis Trueba

2006-01-01

114

Fermion Zero Modes and Topological-charge on a Domain Wall of the D-brane-like Dot  

NASA Astrophysics Data System (ADS)

Anomalous excitations in the electron state of self-assembled InAs quantum dots have been analyzed from viewpoint of field-theoretical formula. It is suggested strongly that exotic excitations with fractional charges might exist in the semiconductor-dot with the domain wall shell. We have discussed the toy-model of the quantum-dot, which is composed of three degenarated D4-brane-like solitons.

Kanazawa, Ikuzo

2015-03-01

115

Topological pumping over a photonic Fibonacci quasicrystal  

E-print Network

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

116

Topological X-Rays Revisited  

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

117

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

118

Nonequilibrium green function approach to elastic and inelastic spin-charge transport in topological insulator-based heterostructures and magnetic tunnel junctions  

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

119

a Comment on Topological Field Theory Quantization and Stochastic Processes  

Microsoft Academic Search

We discuss the relation between different quantization approaches to topological field theories by deriving a connection between Bogomol'nyi and Langevin equations for stochastic processes which evolve towards an equilibrium state governed by the topological charge.

L. F. Cugliandolo; G. Lozano; H. Montani; F. A. Schaposnik

1990-01-01

120

The topological description of coronal magnetic fields  

NASA Technical Reports Server (NTRS)

Determining the structure and behavior of solar coronal magnetic fields is a central problem in solar physics. At the photosphere, the field is believed to be strongly localized into discrete flux tubes. After providing a rigorous definition of field topology, how the topology of a finite collection of flux tubes may be classified is discussed.

Berger, Mitchell A.

1986-01-01

121

Topological censorship.  

NASA Astrophysics Data System (ADS)

Classically, all topologies are allowed as solutions to the Einstein equations. However, one does not observe any topological structures on medium range distance scales, that is scales that are smaller than the size of the observed universe but larger than the microscopic scales for which quantum gravity becomes important. Recently, Friedman, Schleich and Witt (1993) have proven that there is topological censorship on these medium range distance scales: the Einstein equations, locally positive energy, and local predictability of physics imply that any medium distance scale topological structures cannot be seen. More precisely we show that the topology of physically reasonable isolated systems is shrouded from distant observers, or in other words there is a topological censorship principle.

Schleich, K.; Witt, D. M.

122

Topological Censorship  

E-print Network

Classically, all topologies are allowed as solutions to the Einstein equations. However, one does not observe any topological structures on medium range distance scales, that is scales that are smaller than the size of the observed universe but larger than the microscopic scales for which quantum gravity becomes important. Recently, Friedman, Schleich and Witt have proven that there is topological censorship on these medium range distance scales: the Einstein equations, locally positive energy, and local predictability of physics imply that any medium distance scale topological structures cannot be seen. More precisely, we show that the topology of physically reasonable isolated systems is shrouded from distant observers, or in other words there is a topological censorship principle.

Kristin Schleich; Donald M. Witt

1999-03-17

123

Topological censorship  

Microsoft Academic Search

Classically, all topologies are allowed as solutions to the Einstein\\u000aequations. However, one does not observe any topological structures on medium\\u000arange distance scales, that is scales that are smaller than the size of the\\u000aobserved universe but larger than the microscopic scales for which quantum\\u000agravity becomes important. Recently, Friedman, Schleich and Witt have proven\\u000athat there is topological

Kristin Schleich; Donald M. Witt

1993-01-01

124

Network Topologies  

NSDL National Science Digital Library

Network topology is the physical arrangement of the switching devices of a network connecting a group of computers or buildings. This brief interactive activity, by the Electromechanical Digital Library and Wisconsin Technical College System faculty, explains how and why these connections are made. It showcases common topologies including mesh, bus, star, and ring topologies. Users can click through these various categories at their own speed, replaying animations and rereading explanations as many times as the individual needs. This is a great resource for students and teachers alike to familiarize themselves with network topologies. [ES

Bartelt, Terry L. M.

125

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

E-print Network

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.

Smolyaninov, Igor I

2014-01-01

126

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

E-print Network

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

127

QCD with 2 light quark flavours: Thermodynamics on a 16[sup 3] [times] 8 lattice and glueballs and topological charge on a 16[sup 3] [times] 32 lattice  

SciTech Connect

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

128

Topological Censorship  

E-print Network

All three-manifolds are known to occur as Cauchy surfaces of asymptotically flat vacuum spacetimes and of spacetimes with positive-energy sources. We prove here the conjecture that general relativity does not allow an observer to probe the topology of spacetime: any topological structure collapses too quickly to allow light to traverse it. More precisely, in a globally hyperbolic, asymptotically flat spacetime satisfying the null energy condition, every causal curve from $\\scri^-$ to ${\\scri}^+$ is homotopic to a topologically trivial curve from $\\scri^-$ to ${\\scri}^+$. (If the Poincar\\'e conjecture is false, the theorem does not prevent one from probing fake 3-spheres).

John L. Friedman; Kristin Schleich; Donald M. Witt

1995-06-09

129

Topological pumping over a photonic Fibonacci quasicrystal  

NASA Astrophysics Data System (ADS)

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 off-diagonal Harper model implemented in a photonic waveguide array. However, if the relationship between topological pumps and quasiperiodic systems is generic, one might wonder how to observe it in the canonical and most studied quasicrystalline system in one dimension—the Fibonacci chain. This chain is expected to facilitate a similar phenomenon, yet its discrete nature hinders the experimental study of such topological effects. Here, we overcome this obstacle by utilizing the topological equivalence of a family of quasiperiodic models which ranges from the Fibonacci chain 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 chain.

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

2015-02-01

130

Topology Atlas  

NSDL National Science Digital Library

Hosted by York University, with support from University of Florida, University of Tennessee at Martin, Nipissing University, York University, and the University of Milan, the Topology Atlas Website calls itself a publisher of information related to topology. The site amounts to a vast repository of documents for mathematicians and others interested in topology. A preprints section offers documents dating from December 1995 to the present. An Invited Contributions section holds short surveys of specialized topics including titles like "On Variations of Continuity," and "Atlas of oriented knots and links." Also available at this site are abstracts (for books, published articles, and research announcements), journals, TopCom (a magazine for the topology community), and more.

131

Topological Acoustics  

NASA Astrophysics Data System (ADS)

The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

2015-03-01

132

Topological acoustics.  

PubMed

The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers. PMID:25839273

Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

2015-03-20

133

Influence of the variation of geometrical and topological traits on light interception efficiency of apple trees: sensitivity analysis and metamodelling for ideotype definition  

PubMed Central

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

134

Dynamic topological logic  

Microsoft Academic Search

Dynamic topological logic provides a context for studying the confluence of the topological semantics for S4, topological dynamics, and temporal logic. The topological semantics for S4 is based on topological spaces rather than Kripke frames. In this semantics, ? is interpreted as topological interior. Thus S4 can be understood as the logic of topological spaces, and ? can be understood

Philip Kremer; Grigori Mints

2005-01-01

135

Dynamic topological logic  

Microsoft Academic Search

Dynamic topological logic provides a context for studying the confluence of the topological semantics for S4, topological dynamics, and temporal logic. The topological semantics for S4 is based on topological spaces rather than Kripke frames. In this semantics, is interpreted as topological interior. Thus S4 can be understood as the logic of topological spaces, and can be understood as a

Philip Kremer; Grigori Mints

136

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

E-print Network

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 obtained. It is revealed that monopoles and strings are located in different spatial dimensions and their topological charges are just the winding numbers of $\\phi$-mapping.

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

2005-12-27

137

Topology of electronic bands and Topological Order  

E-print Network

Topology of electronic bands and Topological Order R. Shankar The Institute of Mathematical Sciences, Chennai TIFR, 26th April, 2011 #12;Outline IQHE and the Chern Invariant Topological insulators and the Z2 invariant Topological order Exactly solved models with topological order A model with everything

138

Interplay of Sequence, Topology and Termini Charge in Determining the Stability of the Aggregates of GNNQQNY Mutants: A Molecular Dynamics Study  

PubMed Central

This study explores the stabilities of single sheet parallel systems of three sequence variants of 1GNNQQNY7, N2D, N2S and N6D, with variations in aggregate size (5–8) and termini charge (charged or neutral). The aggregates were simulated at 300 and 330 K. These mutations decrease amyloid formation in the yeast prion protein Sup35. The present study finds that these mutations cause instability even in the peptide context. The protonation status of termini is found to be a key determinant of stabilities; other determinants are sequence, position of mutation and aggregate size. All systems with charged termini are unstable, whereas both stable and unstable systems are found when the termini are neutral. When termini are charged, the largest stable aggregate for the N2S and N6D systems has 3 to 4 peptides whereas N2D mutation supports oligomers of larger size (5-and 6-mers) as well. Mutation at 2nd position (N2S and N2D) results in fewer H-bonds at the mutated as well as neighboring (Gly1/Gln4) positions. However, no such effect is found if mutation is at 6th position (N6D). The effect of Asn?Asp mutation depends on the position and termini charge: it is more destabilizing at the 2nd position than at the 6th in case of neutral termini, however, the opposite is true in case of charged termini. Appearance of twist in stable systems and in smaller aggregates formed in unstable systems suggests that twist is integral to amyloid arrangement. Disorder, dissociation or rearrangement of peptides, disintegration or collapse of aggregates and formation of amorphous aggregates observed in these simulations are likely to occur during the early stages of aggregation also. The smaller aggregates formed due to such events have a variety of arrangements of peptides. This suggests polymorphic nature of oligomers and presence of a heterogeneous mixture of oligomers during early stages of aggregation. PMID:24817093

Srivastava, Alka; Balaji, Petety V.

2014-01-01

139

Dynamical overlap fermion at fixed topology  

E-print Network

We launched a project to perform dymanical fermion simulations using the overlap fermion formulation for sea quarks. In order to avoid the appearace of near-zero modes of the hermitian Wilson-Dirac operator $H_W$, we introduce a pair of extra Wilson fermions with a large negative mass term. Crossing of the topological boundary is then strictly prohibited, and the topological charge is conserved during simulations. It makes the simulations substantially faster compared to the algorithms which allow the topology change. We discuss on the finite volume effects due to the fixed global topology.

JLQCD collaboration; S. Hashimoto; S. Aoki; H. Fukaya; K. Kanaya; T. Kaneko; H. Matsufuru; M. Okamoto; T. Onogi; N. Yamada

2006-10-02

140

Influence of topology on the scale setting  

E-print Network

Recently a new method to set the scale in lattice gauge theories, based on the gradient flow generated by the Wilson action, has been proposed, and the systematic errors of the new scales t0 and w0 have been investigated by various groups. The Wilson flow provides also an interesting alternative smoothing procedure in particular useful for the measurement of the topological charge as a pure gluonic observable. We show the viability of this method for N=1 supersymmetric Yang-Mills theory by analysing the configurations produced by the DESY-Muenster collaboration. For increasing flow time the topological charge quickly approaches near-integer values. The topological susceptibility has been measured for different fermion masses and its value is observed to approach zero in the chiral limit. Finally, the relation between the scale defined by the Wilson flow and the topological charge has been investigated, demonstrating a correlation between these two quantities.

Georg Bergner; Pietro Giudice; Istvan Montvay; Gernot Münster; Stefano Piemonte

2014-11-25

141

A new topological aspect in the O( n) symmetric time-dependent Ginzburg-Landau model  

Microsoft Academic Search

With the aid of ?-mapping topological current theory, the topological structure of vortices and the topological quantization of their topological charges in the TDGL model are obtained under the condition that the Jacobian D(?x) ? 0. When D(?x) = 0, it is shown that there exists the crucial branch process case. Based on the implicit function theorem and the Taylor

Yishi Duan; Ying Jiang; Tao Xu

1999-01-01

142

Topological BF field theory description of topological insulators  

E-print Network

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 $E \\cdot B$ 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.

Gil Young Cho; Joel E. Moore

2010-12-03

143

Topological Inference  

Microsoft Academic Search

Geographical database systems deal with certainbasic topological relations such as "A overlapsB" and "B contains C" between simplyconnected regions in the plane. It is of greatinterest to make sound inferences from elementarystatements of this form. This problem hasbeen identified extensively in the recent literature,but very limited progress has been madetowards addressing the considerable technicaldifficulties involved. In this paper we studythe

Michelangelo Grigni; Dimitris Papadias; Christos H. Papadimitriou

1995-01-01

144

Topological Compactons  

E-print Network

One dimensional topological kink which has strictly finite size without any exponential or power-like tail is presented. It can be observed in a simple mechanical system akin to the one used in order to demonstrate sinus-Gordon solitons.

H. Arodz

2002-01-02

145

Topological Compactons  

Microsoft Academic Search

One dimensional topological kink which has strictly finite size without any exponential or power-like tail is presented. It can be observed in a simple mechanical system akin to the one used in order to demonstrate sinus-Gordon solitons.

H. Arodz

2002-01-01

146

Topological Compactons  

NASA Astrophysics Data System (ADS)

One dimensional topological kink which has strictly finite size without any exponential or power-like tail is presented. It can be observed in a simple mechanical system akin to the one used in order to demonstrate sinus-Gordon solitons.

Arodz, H.

2002-05-01

147

Topological quantization of the spin Hall effect in two-dimensional paramagnetic semiconductors  

Microsoft Academic Search

We propose models of two-dimensional paramagnetic semiconductors where the intrinsic spin Hall effect is exactly quantized in integer units of a topological charge. The model describes a topological insulator in the bulk and a ``holographic metal'' at the edge, where the number of extended edge states crossing the Fermi level is dictated by (exactly equal to) the bulk topological charge.

Xiao-Liang Qi; Yong-Shi Wu; Shou-Cheng Zhang

2006-01-01

148

The Bifurcation of the Topological Structure in the Sunspot's Electric Topological Current with Locally Gauge-invariant Maxwell-Chern-Simons Term  

E-print Network

The topological structure of the electric topological current of the locally gauge invariant Maxwell-Chern-Simons Model and its bifurcation is studied. The electric topological charge is quantized in term of winding number. The Hopf indices and Brouwer degree labeled the local topological structure of the electric topological current. Using $\\Phi $-mapping method and implicity theory, the electric topological current is found generating or annihilating at the limit points and splitting or merging at the bifurcate points. The total electric charge holds invariant during the evolution.

Sheng Li; Yishi Duan

1998-10-09

149

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

150

Communication Definitions... general definition  

E-print Network

Communication Definitions... general definition "the process of conveying information from a sender to a receiver with the use of a medium in which the communicated information is understood the same way by both sender and receiver" (Wikipedia)! Biological communication Action by one organism (individual

Jones, Ian L.

151

Fractal Topology Foundations  

E-print Network

In this paper, we introduce the foundation of a fractal topological space constructed via a family of nested topological spaces endowed with subspace topologies, where the number of topological spaces involved in this family is related to the appearance of new structures on it. The greater the number of topological spaces we use, the stronger the subspace topologies we obtain. The fractal manifold model is brought up as an illustration of space that is locally homeomorphic to the fractal topological space.

Helene Porchon

2012-01-25

152

Topological Puzzles  

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

153

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

SciTech Connect

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

154

Computational Topology: An Introduction  

E-print Network

7 Computational Topology: An Introduction G¨unter Rote and Gert Vegter 7.1 Introduction Topology, the distance between points, or the curvature of a surface, are irrelevant to topology. Com- putational topology deals with the complexity of topological problems, and with the design of efficient algorithms

Vegter, Gert

155

The topological structure of the vortices in the O(n) symmetric TDGL model  

Microsoft Academic Search

In the light of $\\\\phi $--mapping method and topological current theory, the\\u000atopological structure of the vortex state in TDGL model and the topological\\u000aquantization of the vortex topological charges are investigated. It is pointed\\u000aout that the topological charges of the vortices in TDGL model are described by\\u000athe Winding numbers of $\\\\phi $--mapping which are determined in terms

Yishi Duan; Ying Jiang; Tao Xu

1998-01-01

156

Topological BF field theory description of topological insulators  

SciTech Connect

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

157

Topological defect system in O(n) symmetric time-dependent Ginzburg-Landau model  

Microsoft Academic Search

We present a new generalized topological current in terms of the order parameter field $\\\\vec \\\\phi$ to describe the topological defect system in O(n) symmetric time-dependent Ginzburg-Landau model. With the aid of the $% \\\\phi$-mapping method, the structure of the topological defects and the topological quantization of their topological charges in TDGL model are obtained under the condition that the

Ying Jiang

2000-01-01

158

Topological entropy for multidimensional perturbations of snap-back repellers and  

E-print Network

Topological entropy for multidimensional perturbations of snap-back repellers and one a snap-back repeller, then F has a positive topological entropy for all close enough to 0. 1-dimensional and show that if f has a snap-back repeller (for a discussion of its definition see Definition 3

Zgliczynski, Piotr

159

Topological Black Holes -- Outside Looking In  

E-print Network

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

160

Topological susceptibility with the improved Asqtad action  

SciTech Connect

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

161

T-Duality and Topological Insulators  

E-print Network

It is well known that topological insulators are classified by a family of groups, which coincidentally also classifies D-brane charges on orientifolds in string theory. In this letter, we extend this correlation via a geometric analog of the real Fourier transform to obtain a novel duality of topological insulators that can be viewed as a condensed matter analog of T-duality in string theory.

Mathai, Varghese

2015-01-01

162

T-Duality of Topological Insulators  

E-print Network

Topological insulators and D-brane charges in string theory can both be classified by the same family of groups. In this letter, we extend this connection via a geometric transform, giving a novel duality of topological insulators which can be viewed as a condensed matter analog of T-duality in string theory. For 2D Chern insulators, this duality exchanges the rank and Chern number of the valence bands.

Varghese Mathai; Guo Chuan Thiang

2015-04-08

163

Extracting Physics from Topologically Frozen Markov Chains  

E-print Network

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

164

Topological mechanisms as classical spinor fields  

E-print Network

A mechanism is a zero-energy motion of a mechanical structure that does not stretch or compress any of its components. Here, we focus on a special class of mechanisms that we dub topological because they are insensitive to smooth changes in material parameters. Topological mechanisms do not arise from local under-coordination, but they can be localized to solitons in the underlying structure. In this letter, we exploit supersymmetry to develop a real-space formalism whereby a topological mechanism can be described as a classical spinor whose real components are the soliton-induced displacement and stress fields. Our analytical approach goes beyond topological band theory by addressing the non-linearity and inhomogeneity of the underlying structure key to the very definition of a mechanism. We apply this general method to an activated mechanism, inspired by the organic molecule polyacetylene, that can propagate down an assembly line without deploying the whole structure.

Vincenzo Vitelli; Nitin Upadhyaya; Bryan Gin-ge Chen

2014-07-11

165

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

166

Topological insulators and superconductors from string theory  

SciTech Connect

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

167

Deficient topological measures and functionals generated by them  

SciTech Connect

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

168

Soft topological objects in topological media  

E-print Network

Topological invariants in terms of the Green's function in momentum and real space determine properties of smooth textures within topological media. In space dimension D=1 the topological invariant N_3 in terms of the Green's function G(\\omega,k_x,x) determines the fermion number of the 1D soliton, while in space dimension D=3 the topological invariant N_5 in terms of the Green's function G(\\omega,k_x,k_y,k_z,z) determines quantization of Hall conductivity in the soliton plane within the topological insulators.

Jukka I. Vayrynen; G. E. Volovik

2011-02-16

169

Submitted to Topology Proceedings  

E-print Network

Submitted to Topology Proceedings DENSE ARC COMPONENTS IN WEAKENED TOPOLOGICAL GROUPS JON W. SHORT Abstract. We will show how to construct metrizable group topologies on the subgroups and quotient groups of R that are weaker than the standard topologies. Even though these groups can be very complicated, we

Short, Jon W.

170

Gapped symmetry preserving surface state for the electron topological insulator  

E-print Network

It is well known that the three-dimensional (3D) electronic topological insulator (TI) with charge-conservation and time-reversal symmetry cannot have a trivial insulating surface that preserves symmetry. It is often ...

Wang, Chong

171

Section 3: Topology of Introduction  

E-print Network

Section 3: Topology of orbifolds S. Choi Introduction Topology of 2-orbifolds Topology of 2-approach to the universal covering spaces 2-orbifolds, triangulations, and topological constructions and covering spaces 3: Topology of orbifolds S. Choi Introduction Topology of 2-orbifolds Topology of 2-orbifolds Smooth

Choi, Suhyoung

172

P-V Criticality of Topological Black Holes in Lovelock-Born-Infeld Gravity  

E-print Network

To understand the effect of third order Lovelock gravity, $P-V$ criticality of topological AdS black holes in Lovelock-Born-Infeld gravity is investigated. The thermodynamics is further explored with some more extensions and details than the former literature. A detailed analysis of the limit case $\\beta\\rightarrow\\infty$ is performed for the seven-dimensional black holes. It is shown that for the spherical topology, $P-V$ criticality exists for both the uncharged and charged cases. Our results demonstrate again that the charge is not the indispensable condition of $P-V$ criticality. It may be attributed to the effect of higher derivative terms of curvature because similar phenomenon was also found for Gauss-Bonnet black holes. For $k=0$, there would be no $P-V$ criticality. Interesting findings occur in the case $k=-1$, in which positive solutions of critical points are found for both the uncharged and charged cases. However, the $P-v$ diagram is quite strange. To check whether these findings are physical, we give the analysis on the non-negative definiteness condition of entropy. It is shown that for any nontrivial value of $\\alpha$, the entropy is always positive for any specific volume $v$. Since no $P-V$ criticality exists for $k=-1$ 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 is absent in the Gauss-Bonnet black holes, which makes the critical points satisfy the constraint of non-negative definiteness condition of entropy. We also check the Gibbs free energy graph and the "swallow tail" behavior can be observed. Moreover, the effect of nonlinear electrodynamics is also included in our research.

Jie-Xiong Mo; Wen-Biao Liu

2014-01-04

173

- 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

174

Topological binding and elastic interactions of microspheres and fibres in a nematic liquid crystal.  

PubMed

We present a detailed analysis of topological binding and elastic interactions between a long, and micrometer-diameter fiber, and a microsphere in a homogeneously aligned nematic liquid crystal. Both objects are surface treated to produce strong perpendicular anchoring of the nematic liquid crystal. We use the opto-thermal micro-quench of the laser tweezers to produce topological defects with prescribed topological charge, such as pairs of a Saturn ring and an anti-ring, hyperbolic and radial hedgehogs on a fiber, as well as zero-charge loops. We study the entanglement and topological charge interaction between the topological defects of the fiber and sphere and we observe a huge variety of different entanglement topologies and defect-mediated elastic bindings. We explain all observed phenomena with simple topological rule: like topological charges repel each other and opposite topological charges attract. These binding mechanisms not only demonstrate the fascinating topology of nematic colloids, but also open a novel route to the assembly of very complex topological networks of fibers, spheres and other objects for applications in liquid crystal photonics. PMID:25813607

Nikkhou, M; Škarabot, M; Muševi?, I

2015-03-01

175

Bosonic topological insulator in three dimensions and the statistical Witten effect  

E-print Network

Bosonic topological insulator in three dimensions and the statistical Witten effect Max A-known that one signature of the three-dimensional electron topological insulator is the Witten effect-odd-integer polarization charge. In the present work, we propose a corre- sponding phenomenon for the topological insulator

176

Holographic Charged Renyi Entropies  

E-print Network

We construct a new class of entanglement measures by extending the usual definition of Renyi entropy to include a chemical potential. These charged Renyi entropies measure the degree of entanglement in different charge sectors of the theory and are given by Euclidean path integrals with the insertion of a Wilson line encircling the entangling surface. We compute these entropies for a spherical entangling surface in CFT's with holographic duals, where they are related to entropies of charged black holes with hyperbolic horizons. We also compute charged Renyi entropies in free field theories.

Alexandre Belin; Ling-Yan Hung; Alexander Maloney; Shunji Matsuura; Robert C. Myers; Todd Sierens

2015-01-20

177

25 CFR 700.105 - Utility charges.  

Code of Federal Regulations, 2010 CFR

...Instructions Definitions § 700.105 Utility charges. Utility charges means the cost for heat, lighting, hot water, electricity, natural gas, butane, propane, wood, coal or other fuels water, sewer and trash...

2010-04-01

178

25 CFR 700.105 - Utility charges.  

Code of Federal Regulations, 2011 CFR

...Instructions Definitions § 700.105 Utility charges. Utility charges means the cost for heat, lighting, hot water, electricity, natural gas, butane, propane, wood, coal or other fuels water, sewer and trash...

2011-04-01

179

Detecting topological currents in graphene superlattices  

NASA Astrophysics Data System (ADS)

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 currents originating from graphene’s two valleys are predicted to flow in opposite directions and combine to produce long-range charge neutral flow. We observed this effect as a nonlocal voltage at zero magnetic field in a narrow energy range near Dirac points at distances as large as several micrometers away from the nominal current path. Locally, topological currents are comparable in strength with the applied current, indicating large valley-Hall angles. The long-range character of topological currents and their transistor-like control by means of gate voltage can be exploited for information processing based on valley degrees of freedom.

Gorbachev, R. V.; Song, J. C. W.; Yu, G. L.; Kretinin, A. V.; Withers, F.; Cao, Y.; Mishchenko, A.; Grigorieva, I. V.; Novoselov, K. S.; Levitov, L. S.; Geim, A. K.

2014-10-01

180

Detecting topological currents in graphene superlattices.  

PubMed

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 currents originating from graphene's two valleys are predicted to flow in opposite directions and combine to produce long-range charge neutral flow. We observed this effect as a nonlocal voltage at zero magnetic field in a narrow energy range near Dirac points at distances as large as several micrometers away from the nominal current path. Locally, topological currents are comparable in strength with the applied current, indicating large valley-Hall angles. The long-range character of topological currents and their transistor-like control by means of gate voltage can be exploited for information processing based on valley degrees of freedom. PMID:25342798

Gorbachev, R V; Song, J C W; Yu, G L; Kretinin, A V; Withers, F; Cao, Y; Mishchenko, A; Grigorieva, I V; Novoselov, K S; Levitov, L S; Geim, A K

2014-10-24

181

Fractional topological insulators in three dimensions.  

PubMed

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

182

Fractional Topological Insulators in Three Dimensions  

SciTech Connect

Topological insulators can be generally defined by a topological field theory with an axion angle {theta} of 0 or {pi}. 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{sub 3}, and a 'halved' fractional quantum Hall effect on the surface with Hall conductance of the form {sigma}{sub H}=(p/q)(e{sup 2}/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{sub 3} and allows fractional values consistent with T invariance.

Maciejko, Joseph; Zhang Shoucheng [Department of Physics, Stanford University, Stanford, California 94305 (United States); Qi Xiaoliang [Microsoft Research, Station Q, Elings Hall, University of California, Santa Barbara, California 93106 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Karch, Andreas [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

2010-12-10

183

Strongly Topological Interactions of Tensionless Strings  

E-print Network

The tensionless limit of classical string theory may be formulated as a topological theory on the world-sheet. A vector density carries geometrical information in place of an internal metric. It is found that path-integral quantization allows for the definition of several, possibly inequivalent quantum theories. String amplitudes are constructed from vector densities with zeroes for each in- or out-going string. It is shown that independence of a metric in quantum mechanical amplitudes implies that the dependence on such vector density zeroes is purely topological. For example, there is no need for integration over their world-sheet positions.

Bo Sundborg

1994-06-30

184

Strongly topological interactions of tensionless strings  

E-print Network

The tensionless limit of classical string theory may be formulated as a topological theory on the world-sheet. A vector density carries geometrical information in place of an internal metric. It is found that path-integral quantization allows for the definition of several, possibly inequivalent quantum theories. String amplitudes are constructed from vector densities with zeroes for each in- or out-going string. It is shown that independence of a metric in quantum mechanical amplitudes implies that the dependence on such vector density zeroes is purely topological. For example, there is no need for integration over their world-sheet positions.

Sundborg, B

1994-01-01

185

Topological interactions in broken gauge theories  

Microsoft Academic Search

This thesis deals with planar gauge theories in which some gauge group G is spontaneously broken to a finite subgroup H. The spectrum consists of magnetic vortices, global H charges and dyonic combinations exhibiting topological Aharonov-Bohm interactions. Among other things, we review the Hopf algebra D(H) related to this residual discrete H gauge theory, which provides an unified description of

Mark de Wild Propitius

1995-01-01

186

QCD glueball sum rules and vacuum topology  

E-print Network

Several key problems of QCD sum rules in the spin-0 glueball channels are resolved by implementing nonperturbative short-distance physics from direct instantons and topological charge screening. A lattice-based instanton size distribution and the IR renormalization of the nonperturbative Wilson coefficients are also introduced. Results of a comprehensive quantitative sum rule analysis are reviewed and their implications discussed.

Hilmar Forkel

2006-08-23

187

Periodic table for topological insulators and superconductors  

Microsoft Academic Search

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

188

The topological quantization and bifurcation of the topological linear defects  

E-print Network

In the light of $\\phi$-mapping method and topological current theory, the topological structure and the topological quantization of topological linear defects are obtained under the condition that the Jacobian $J(\\phi/v) \

Yishi Duan; Ying Jiang; Guohong Yang

1998-10-08

189

The topological quantization and bifurcation of the topological linear defects  

Microsoft Academic Search

In the light of $\\\\phi$-mapping method and topological current theory, the topological structure and the topological quantization of topological linear defects are obtained under the condition that the Jacobian $J(\\\\phi\\/v) \\\

Yishi Duan; Ying Jiang; Guohong Yang

1998-01-01

190

An Acoustic Charge Transport Imager for High Definition Television Applications: Low-Voltage SAW Amplifiers on Multilayer GaAs/ZnO Substrates  

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

191

Coulomb screening in graphene with topological defects  

E-print Network

We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb impurity. The period of variation depends on the conical defect. In the presence of the conical defect, the Fano resonances begin to appear in the transport cross-section for a lower value of the Coulomb charge. For both sub and supercritical regime we derive the dependence of LDOS on the conical defect. The effects of generalized boundary condition on the physical observables are also discussed.

Baishali Chakraborty; Kumar S. Gupta; Siddhartha Sen

2015-02-20

192

Spatial fluctuations of helical Dirac fermions on the surface of topological insulators (DMR-0819860)  

E-print Network

of the topological insulator materials have large dielectric constants. Reducing charge defects will be required for Dirac electrons in graphene. Bulk defects in a topological insulators play a similar role; however, many for these novel states. Resesarch in PCCM is directed towards reducing charge defects in a new class

Petta, Jason

193

Genetics Home Reference: CHARGE syndrome  

MedlinePLUS

... 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) ...

194

Boundaries and Topological Algorithms  

E-print Network

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

195

Topological quantization of the spin Hall effect in two-dimensional paramagnetic semiconductors  

SciTech Connect

We propose models of two-dimensional paramagnetic semiconductors where the intrinsic spin Hall effect is exactly quantized in integer units of a topological charge. The model describes a topological insulator in the bulk and a 'holographic metal' at the edge, where the number of extended edge states crossing the Fermi level is dictated by (exactly equal to) the bulk topological charge. We also demonstrate the spin Hall effect explicitly in terms of the spin accumulation caused by the adiabatic flux insertion.

Qi, X.-L.

2010-03-02

196

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

E-print Network

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

197

Optical image encryption topology.  

PubMed

Optical image encryption topology is proposed based on the principle of random-phase encoding. Various encryption topological units, involving peer-to-peer, ring, star, and tree topologies, can be realized by an optical 6f system. These topological units can be interconnected to constitute an optical image encryption network. The encryption and decryption can be performed in both digital and optical methods. PMID:19838280

Yong-Liang, Xiao; Xin, Zhou; Qiong-Hua, Wang; Sheng, Yuan; Yao-Yao, Chen

2009-10-15

198

Topological Confinement in Bilayer Graphene  

NASA Astrophysics Data System (ADS)

We study a new type of one-dimensional chiral states that can be created in bilayer graphene (BLG) by electrostatic lateral confinement. These states appear on the domain walls separating insulating regions experiencing the opposite gating polarity. While the states are similar to conventional solitonic zero modes, their properties are defined by the unusual chiral BLG quasiparticles, from which they derive. The number of zero mode branches is fixed by the topological vacuum charge of the insulating BLG state. We discuss how these chiral states can manifest experimentally and emphasize their relevance for valleytronics.

Martin, Ivar; Blanter, Ya. M.; Morpurgo, A. F.

2008-01-01

199

A Proposed Definition of Functional Integrals  

E-print Network

Functional integrals are defined in terms of families of locally compact topological groups and their associated Banach-valued Haar integrals. The definition abandons the hope of defining a genuine measure on the integral domain, and instead gives a topological realization of localization in the integral domain leading to measurable subspaces that characterize meaningful functional integrals. The proposed definition is natural in the sense that it includes other successful approaches to functional integrals within a broader framework. In turn, the framework suggests new and potentially useful functional integrals.

J. LaChapelle

2015-01-07

200

Topological Quantization of Linear Defects  

Microsoft Academic Search

Using phiv-mapping method and topological current theory, we get the topological structure and the topological quantization of topological linear defects and point out that the topological quantum numbers of the linear defects are described by the Winding numbers of phiv-mapping which are determined in terms of the Hopf indices and the Brouwer degrees. All the topological linear defects are generated

Yi-shi Duan; Ying Jiang; Guo-hong Yang

1998-01-01

201

Computer Science Computational topology  

E-print Network

Part 6 Computer Science #12;#12;Computational topology Denis Blackmore and Thomas J. Peters 1. Introduction The emphasis here will be upon how point-set topology can be applied to computing on geometric objects embedded in R3 . The fundamental topological concept of a neighborhood generalizes limits over

Peters, Thomas J.

202

Computational Topology Afra Zomorodian  

E-print Network

Computational Topology Afra Zomorodian Dartmouth College November 3, 2009 1 Introduction According to the Oxford English Dictionary, the word topology is derived of topos (Ø ÔÓ ) meaning place, and -logy (ÐÓ ), a variant of the verb д Ò, meaning to speak. As such, topology speaks about places: how local neighborhoods

Zomorodian, Afra

203

Cosmic topology affects dynamics  

E-print Network

The role of global topology in the dynamics of the Universe is poorly understood. Along with observational programmes for determining the topology of the Universe, some small theoretical steps have recently been made. Heuristic Newtonian-like arguments suggest a topological acceleration effect that differs for differing spatial sections. A relativistic spacetime solution solution shows that the effect is not just a Newtonian artefact.

Boudewijn F. Roukema

2012-01-04

204

Modeling Internet topology  

Microsoft Academic Search

The topology of a network, or a group of networks such as the Internet, has a strong bearing on many management and performance issues. Good models of the topological structure of a network are essential for developing and analyzing internetworking technology. This article discusses how graph-based models can be used to represent the topology of large networks, particularly aspects of

K. I. Calvert; M. B. Doar; E. W. Zegura

1997-01-01

205

4D Topological Mass by Gauging Spin  

E-print Network

We propose a spin gauge field theory in which the curl of a Dirac fermion current density plays the role of the pseudovector charge density. In this field-theoretic model, spin interactions are mediated by a single scalar gauge boson in its antisymmetric tensor formulation. We show that these long range spin interactions induce a gauge invariant photon mass in the one-loop effective action. The fermion loop generates a coupling between photons and the spin gauge boson, which acquires thus charge. This coupling represents also an induced, gauge invariant, topological mass for the photons, leading to the Meissner effect. The one-loop effective equations of motion for the charged spin gauge boson are the London equations. We propose thus spin gauge interactions as an alternative, topological mechanism for superconductivity in which no spontaneous symmetry breaking is involved.

Ishita D. Choudhury; M. Cristina Diamantini; Giuseppe Guarnaccia; Amitabha Lahiri; Carlo A. Trugenberger

2015-03-21

206

4D Topological Mass by Gauging Spin  

E-print Network

We propose a spin gauge field theory in which the curl of a Dirac fermion current density plays the role of the pseudovector charge density. In this field-theoretic model, spin interactions are mediated by a single scalar gauge boson in its antisymmetric tensor formulation. We show that these long range spin interactions induce a gauge invariant photon mass in the one-loop effective action. The fermion loop generates a coupling between photons and the spin gauge boson, which acquires thus charge. This coupling represents also an induced, gauge invariant, topological mass for the photons, leading to the Meissner effect. The one-loop effective equations of motion for the charged spin gauge boson are the London equations. We propose thus spin gauge interactions as an alternative, topological mechanism for superconductivity in which no spontaneous symmetry breaking is involved.

Choudhury, Ishita D; Guarnaccia, Giuseppe; Lahiri, Amitabha; Trugenberger, Carlo A

2015-01-01

207

Vortex Motion In Charged Fluids  

E-print Network

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

208

Ectoplasm has no topology: The prelude  

NASA Astrophysics Data System (ADS)

Preliminary evidence is presented that a long overlooked and critical element in the fundamental definition of a general theory of integration over curved Wess-Zumino superspace lies with the imposition of "the Ethereal Conjecture" which states the necessity of the superspace to be topologically "close" to its purely bosonic sub-manifold. As a step in proving this, a new theory of integration based on closed super p-forms is proposed.

Gates, S. James

209

Strongly Topological Interactions of Tensionless Strings  

Microsoft Academic Search

The tensionless limit of classical string theory may be formulated as a topological theory on the world-sheet. A vector density carries geometrical information in place of an internal metric. It is found that path-integral quantization allows for the definition of several, possibly inequivalent quantum theories. String amplitudes are constructed from vector densities with zeroes for each in- or out-going string.

Bo Sundborg

1994-01-01

210

Coulomb screening in graphene with topological defects  

E-print Network

We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb imp...

Chakraborty, Baishali; Sen, Siddhartha

2015-01-01

211

Game Theory and Topological Phase Transition  

E-print Network

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

2008-03-29

212

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

213

Network topology analysis.  

SciTech Connect

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

214

Quartic Quasi-Topological-Born-Infeld Gravity  

E-print Network

In this paper, quartic quasi-topological black holes in the presence of a nonlinear electromagnetic Born-Infeld field is presented. By using the metric parameters, the charged black hole solutions of quasi-topological Born-Infeld gravity is considered. The thermodynamics of these black holes are investigated and I show that the thermodynamics and conserved quantities verify the first law of thermodynamics. I also introduce the thermodynamics of asymptotically AdS rotating black branes with flat horizon of these class of solutions and I calculate the finite action by use of the counterterm method inspired by AdS/CFT correspondence.

Ghanaatian, Mohammad

2015-01-01

215

Photonic Floquet topological insulators  

NASA Astrophysics Data System (ADS)

Topological insulators are a new phase of matter, with the striking property that conduction of electrons occurs only on the surface. In two dimensions, surface electrons in topological insulators do not scatter despite defects and disorder, providing robustness akin to superconductors. Topological insulators are predicted to have wideranging applications in fault-tolerant quantum computing and spintronics. Recently, large theoretical efforts were directed towards achieving topological insulation 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. However, since magnetic effects are very weak at optical frequencies, realizing photonic topological insulators with scatterfree edge states requires a fundamentally different mechanism - one that is free of magnetic fields. Recently, a number of proposals for photonic topological transport have been put forward. Specifically, one suggested temporally modulating 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, where temporal variations in solidstate systems induce topological edge states. Here, we propose and experimentally demonstrate the first external field-free photonic topological insulator 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 acts as `time'. Thus the waveguides' helicity breaks zreversal symmetry in the sense akin to Floquet Topological Insulators. This structure results in scatter-free, oneway edge states that are topologically protected from scattering.

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

2013-09-01

216

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

217

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

218

Model Realization and Numerical Studies of a Three-Dimensional Bosonic Topological Insulator and Symmetry-Enriched Topological Phases  

E-print Network

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

219

Model Realization and Numerical Studies of a Three-Dimensional Bosonic Topological Insulator and Symmetry-Enriched Topological Phases  

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

220

Preliminary documentation of the MACH (Mesothermal Auroral Charging) code. Report No. 1, March-December 1987  

SciTech Connect

This report documents the input and output considerations for the computer code MACH, and the analytical models incorporated therein. Actual FORTRAN and C coding is not given. MACH has been designed to study Mesothermal Auroral CHarging, and other problems requiring a self-consistent steady-state solution of Poisson's equation with precise kinetic transport of charged particles. The solution space is two-dimensional (axisymmetric) in configuration space, and three-dimensional in velocity space. MACH code features include: limited object-definition capability; Poisson's solution by hybrid SOR; stationary or drifting Maxwellian plasma; and a collisionless Vlasov approximation to particle transport, solved by a reverse trajectory 'inside-out method' augmented with a velocity-space topology search algorithm.

Tautz, M.F.; Cooke, D.C.; Rubin, A.G.; Yates, G.K.

1987-12-18

221

Asymptotic analysis and topological derivatives for shape and topology  

E-print Network

Asymptotic analysis and topological derivatives for shape and topology optimization of elasticity@ibspan.waw.pl Abstract. Topological derivatives for elasticity problems are used in shape and topology optimization to determine the first order topological derivatives of shape func- tionals, and E2 (R) can be used

Paris-Sud XI, Université de

222

Topological insulators/Isolants topologiques An introduction to topological insulators  

E-print Network

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, Université de

223

Topological Quantum Computation with the universal R matrix for Ising anyons  

E-print Network

We show that the braid-group extension of the monodromy-based topological quantum computation scheme of Das Sarma et al. can be understood in terms of the universal R matrix for the Ising model giving similar results to those obtained by direct analytic continuation of multi-anyon Pfaffian wave functions. It is necessary, however, to take into account the projection on spinor states with definite total parity which is responsible for the topological entanglement in the Pfaffian topological quantum computer.

Lachezar S. Georgiev

2008-12-12

224

Tunable Dirac Fermion Dynamics in Topological Insulators  

PubMed Central

Three-dimensional topological insulators are characterized by insulating bulk state and metallic surface state involving relativistic Dirac fermions which are responsible for exotic quantum phenomena and potential applications in spintronics and quantum computations. It is essential to understand how the Dirac fermions interact with other electrons, phonons and disorders. Here we report super-high resolution angle-resolved photoemission studies on the Dirac fermion dynamics in the prototypical Bi2(Te,Se)3 topological insulators. We have directly revealed signatures of the electron-phonon coupling and found that the electron-disorder interaction dominates the scattering process. The Dirac fermion dynamics in Bi2(Te3?xSex) topological insulators can be tuned by varying the composition, x, or by controlling the charge carriers. Our findings provide crucial information in understanding and engineering the electron dynamics of the Dirac fermions for fundamental studies and potential applications. PMID:23934507

Chen, Chaoyu; Xie, Zhuojin; Feng, Ya; Yi, Hemian; Liang, Aiji; He, Shaolong; Mou, Daixiang; He, Junfeng; Peng, Yingying; Liu, Xu; Liu, Yan; Zhao, Lin; Liu, Guodong; Dong, Xiaoli; Zhang, Jun; Yu, Li; Wang, Xiaoyang; Peng, Qinjun; Wang, Zhimin; Zhang, Shenjin; Yang, Feng; Chen, Chuangtian; Xu, Zuyan; Zhou, X. J.

2013-01-01

225

Periodic table for topological insulators and superconductors  

E-print Network

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

2009-01-20

226

Photonic Floquet Topological Insulators  

E-print Network

The topological insulator is a fundamentally new phase of matter, with the striking property that the conduction of electrons occurs only on its surface, not within the bulk, and that conduction is topologically protected. Topological protection, the total lack of scattering of electron waves by disorder, is perhaps the most fascinating and technologically important aspect of this material: it provides robustness that is otherwise known only for superconductors. However, unlike superconductivity and the quantum Hall effect, which necessitate low temperatures or magnetic fields, the immunity to disorder of topological insulators occurs at room temperature and without any external magnetic field. For this reason, topological protection is predicted to have wide-ranging applications in fault-tolerant quantum computing and spintronics. Recently, a large theoretical effort has been directed towards bringing the concept into the domain of photonics: achieving topological protection of light at optical frequencies. ...

Rechtsman, Mikael C; Plotnik, Yonatan; Lumer, Yaakov; Nolte, Stefan; Segev, Mordechai; Szameit, Alexander

2012-01-01

227

Variable Topology on Fractal Manifold  

E-print Network

In this paper, we study the topology associated to the fractal manifold model. It turns out that this topology is actually a family of topologies that gives to the fractal manifold a structure of variable topological space. Additionally, we prove that using the fractal manifold as model for the universe dynamic, the universe expansion is intimately correlated to the variation of the topology.

Helene Porchon

2012-11-15

228

5 CFR 1303.30 - Definitions.  

Code of Federal Regulations, 2012 CFR

... ADMINISTRATIVE PROCEDURES PUBLIC INFORMATION PROVISIONS OF THE ADMINISTRATIVE PROCEDURES ACT Charges for Search and Reproduction § 1303.30 Definitions. For the purpose of these regulations: (a) All the terms defined in the Freedom of...

2012-01-01

229

5 CFR 1303.30 - Definitions.  

Code of Federal Regulations, 2011 CFR

... ADMINISTRATIVE PROCEDURES PUBLIC INFORMATION PROVISIONS OF THE ADMINISTRATIVE PROCEDURES ACT Charges for Search and Reproduction § 1303.30 Definitions. For the purpose of these regulations: (a) All the terms defined in the Freedom of...

2011-01-01

230

40 CFR 60.421 - Definitions.  

Code of Federal Regulations, 2011 CFR

...Standards of Performance for Ammonium Sulfate Manufacture § 60.421 Definitions...the Act and in subpart A. Ammonium sulfate dryer means a unit or vessel into which ammonium sulfate is charged for the...

2011-07-01

231

40 CFR 60.421 - Definitions.  

Code of Federal Regulations, 2012 CFR

...Standards of Performance for Ammonium Sulfate Manufacture § 60.421 Definitions...the Act and in subpart A. Ammonium sulfate dryer means a unit or vessel into which ammonium sulfate is charged for the...

2012-07-01

232

40 CFR 60.421 - Definitions.  

Code of Federal Regulations, 2013 CFR

...Standards of Performance for Ammonium Sulfate Manufacture § 60.421 Definitions...the Act and in subpart A. Ammonium sulfate dryer means a unit or vessel into which ammonium sulfate is charged for the...

2013-07-01

233

40 CFR 60.421 - Definitions.  

Code of Federal Regulations, 2010 CFR

...Standards of Performance for Ammonium Sulfate Manufacture § 60.421 Definitions...the Act and in subpart A. Ammonium sulfate dryer means a unit or vessel into which ammonium sulfate is charged for the...

2010-07-01

234

40 CFR 60.421 - Definitions.  

Code of Federal Regulations, 2014 CFR

...Standards of Performance for Ammonium Sulfate Manufacture § 60.421 Definitions...the Act and in subpart A. Ammonium sulfate dryer means a unit or vessel into which ammonium sulfate is charged for the...

2014-07-01

235

12 CFR 508.2 - Definitions.  

Code of Federal Regulations, 2010 CFR

...OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY REMOVALS, SUSPENSIONS, AND PROHIBITIONS WHERE A CRIME IS CHARGED OR PROVEN § 508.2 Definitions. As used in this part— (a) The term Office means the Office of Thrift Supervision....

2010-01-01

236

Causal Set Topology  

E-print Network

The Causal Set Theory (CST) approach to quantum gravity is motivated by the observation that, associated with any causal spacetime (M,g) is a poset (M,topological and geometric properties that characterise a continuum spacetime in the large. The continuum approximation thus sets the stage for the study of topology in CST. We review the status of causal set topology and present some new results relating poset and spacetime topologies. The hope is that in the process, some of the ideas and questions arising from CST will be made accessible to the larger community of computer scientists and mathematicians working on posets.

Sumati Surya

2008-09-17

237

Notes on topological insulators  

E-print Network

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

238

Manipulating Topological States by Imprinting Non-Collinear Spin Textures  

PubMed Central

Topological magnetic states, such as chiral skyrmions, are of great scientific interest and show huge potential for novel spintronics applications, provided their topological charges can be fully controlled. So far skyrmionic textures have been observed in noncentrosymmetric crystalline materials with low symmetry and at low temperatures. We propose theoretically and demonstrate experimentally the design of spin textures with topological charge densities that can be tailored at ambient temperatures. Tuning the interlayer coupling in vertically stacked nanopatterned magnetic heterostructures, such as a model system of a Co/Pd multilayer coupled to Permalloy, the in-plane non-collinear spin texture of one layer can be imprinted into the out-of-plane magnetised material. We observe distinct spin textures, e.g. vortices, magnetic swirls with tunable opening angle, donut states and skyrmion core configurations. We show that applying a small magnetic field, a reliable switching between topologically distinct textures can be achieved at remanence. PMID:25739643

Streubel, Robert; Han, Luyang; Im, Mi-Young; Kronast, Florian; Rößler, Ulrich K.; Radu, Florin; Abrudan, Radu; Lin, Gungun; Schmidt, Oliver G.; Fischer, Peter; Makarov, Denys

2015-01-01

239

Manipulating Topological States by Imprinting Non-Collinear Spin Textures  

NASA Astrophysics Data System (ADS)

Topological magnetic states, such as chiral skyrmions, are of great scientific interest and show huge potential for novel spintronics applications, provided their topological charges can be fully controlled. So far skyrmionic textures have been observed in noncentrosymmetric crystalline materials with low symmetry and at low temperatures. We propose theoretically and demonstrate experimentally the design of spin textures with topological charge densities that can be tailored at ambient temperatures. Tuning the interlayer coupling in vertically stacked nanopatterned magnetic heterostructures, such as a model system of a Co/Pd multilayer coupled to Permalloy, the in-plane non-collinear spin texture of one layer can be imprinted into the out-of-plane magnetised material. We observe distinct spin textures, e.g. vortices, magnetic swirls with tunable opening angle, donut states and skyrmion core configurations. We show that applying a small magnetic field, a reliable switching between topologically distinct textures can be achieved at remanence.

Streubel, Robert; Han, Luyang; Im, Mi-Young; Kronast, Florian; Rößler, Ulrich K.; Radu, Florin; Abrudan, Radu; Lin, Gungun; Schmidt, Oliver G.; Fischer, Peter; Makarov, Denys

2015-03-01

240

Manipulating topological States by imprinting non-collinear spin textures.  

PubMed

Topological magnetic states, such as chiral skyrmions, are of great scientific interest and show huge potential for novel spintronics applications, provided their topological charges can be fully controlled. So far skyrmionic textures have been observed in noncentrosymmetric crystalline materials with low symmetry and at low temperatures. We propose theoretically and demonstrate experimentally the design of spin textures with topological charge densities that can be tailored at ambient temperatures. Tuning the interlayer coupling in vertically stacked nanopatterned magnetic heterostructures, such as a model system of a Co/Pd multilayer coupled to Permalloy, the in-plane non-collinear spin texture of one layer can be imprinted into the out-of-plane magnetised material. We observe distinct spin textures, e.g. vortices, magnetic swirls with tunable opening angle, donut states and skyrmion core configurations. We show that applying a small magnetic field, a reliable switching between topologically distinct textures can be achieved at remanence. PMID:25739643

Streubel, Robert; Han, Luyang; Im, Mi-Young; Kronast, Florian; Rößler, Ulrich K; Radu, Florin; Abrudan, Radu; Lin, Gungun; Schmidt, Oliver G; Fischer, Peter; Makarov, Denys

2015-01-01

241

Topological pair-density-wave superconducting states.  

PubMed

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

242

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

243

Topological black holes in Horava-Lifshitz gravity  

SciTech Connect

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

244

Ground-State Degeneracy of Topological Phases on Open Surfaces  

NASA Astrophysics Data System (ADS)

We relate the ground state degeneracy of a non-Abelian topological phase on a surface with boundaries to the anyon condensates that break the topological phase into a trivial phase. Specifically, we propose that gapped boundary conditions of the surface are in one-to-one correspondence with the sets of condensates, each being able to completely break the phase, and we substantiate this by examples. The ground state degeneracy 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-Tao-Wu charge-pumping argument for Abelian fractional quantum Hall states to encompass non-Abelian topological phases, in the sense that an anyon loop of a confined anyon winding a nontrivial cycle can pump a condensed anyon from one boundary to another. Such generalized pumping may find applications in quantum control of anyons, eventually realizing topological quantum computation.

Hung, Ling-Yan; Wan, Yidun

2015-02-01

245

Destroying a topological quantum bit by condensing Ising vortices.  

PubMed

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

246

Ground State Degeneracy of Topological Phases on Open Surfaces  

E-print Network

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

2015-02-22

247

Experimental Discovery of Topological Insulators and Related Superconductors  

SciTech Connect

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

248

Supersymmetric black holes with lens-space topology.  

PubMed

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

249

Topological aspect of black hole with Skyrme hair  

E-print Network

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

250

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

251

Topological susceptibility with the asqtad action  

SciTech Connect

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

252

Topological phase transition without gap closing.  

PubMed

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

253

Topological Phase Transition without Gap Closing  

PubMed Central

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

254

12 CFR 622.76 - Definitions.  

Code of Federal Regulations, 2010 CFR

...AND PROCEDURE Rules and Procedures Applicable to Suspension or Removal of an Individual Where Certain Crimes Are Charged or Proven § 622.76 Definitions. Unless noted otherwise, the definitions set forth in § 622.2 of subpart A shall apply to...

2010-01-01

255

Black hole attractors and the topological string  

Microsoft Academic Search

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

256

Topological interactions in broken gauge theories  

Microsoft Academic Search

This thesis deals with planar gauge theories in which some gauge group G is\\u000aspontaneously broken to a finite subgroup H. The spectrum consists of magnetic\\u000avortices, global H charges and dyonic combinations exhibiting topological\\u000aAharonov-Bohm interactions. Among other things, we review the Hopf algebra D(H)\\u000arelated to this residual discrete H gauge theory, which provides an unified\\u000adescription of

Mark de Wild Propitius

1995-01-01

257

Topological solitons in 8-spinor mie electrodynamics  

SciTech Connect

We investigate the effective 8-spinor field model suggested earlier as the generalization of nonlinear Mie electrodynamics. We first study in pure spinorial model the existence of topological solitons endowed with the nontrivial Hopf invariant Q{sub H}, which can be interpreted as the lepton number. Electromagnetic field being included as the perturbation, we estimate the energy and the spin of the localized charged configuration.

Rybakov, Yu. P., E-mail: soliton4@mail.ru [Peoples' Friendship University of Russia, Department of Theoretical Physics (Russian Federation)

2013-10-15

258

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

259

Unoccupied topological surface state in Bi2Te2Se  

NASA Astrophysics Data System (ADS)

Bias voltage dependent scattering of the topological surface state is studied by scanning tunneling microscopy/spectroscopy for a clean surface of the topological insulator Bi2Te2Se. A strong warping of constant energy contours in the unoccupied part of the spectrum is found to lead to a spin-selective scattering. The topological surface state persists to higher energies in the unoccupied range far beyond the Dirac point, where it coexists with the bulk conduction band. This finding sheds light on the spin and charge dynamics over a wide energy range and opens a way to designing optospintronic devices.

Nurmamat, Munisa; Krasovskii, E. E.; Kuroda, K.; Ye, M.; Miyamoto, K.; Nakatake, M.; Okuda, T.; Namatame, H.; Taniguchi, M.; Chulkov, E. V.; Kokh, K. A.; Tereshchenko, O. E.; Kimura, A.

2013-08-01

260

Topologically Adaptable Snakes  

Microsoft Academic Search

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

261

Topological Insulators & Superconductors  

E-print Network

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 and Superconductors will gather the world- leading researchers in this field to present recent

262

Topological Quantum Distillation  

E-print Network

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.

H. Bombin; M. A. Martin-Delgado

2007-03-29

263

DNA Topology: Fundamentals  

E-print Network

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

264

Topological defects in CFT  

SciTech Connect

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

265

Inet: Internet Topology Generator  

Microsoft Academic Search

Network research often involves the evaluation of new application designs, system architectures, and protocol implementations. Due to the immense scale of the Internet, deploying an Internet-wide system for the purpose of experimental study is nearly impossible. Instead, researchers evaluate their designs using generated random network topologies. In this report, we present a topology generator that is based on Autonomous System

Cheng Jin; Qian Chen; Sugih Jamin

2000-01-01

266

POTLUCK FOOD SAFETY 1. Definition  

E-print Network

POTLUCK FOOD SAFETY 1. Definition: (i) Campus Potluck is a closed food event that is privately funded by the participants, where all group members bring food dishes to share with others in the group. All food provided for the potluck event shall be consumed by members of the group at no charge

267

Geometrically induced electric polarization in conical topological insulators  

E-print Network

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

268

Probing the Chiral Anomaly with Nonlocal Transport in Three-Dimensional Topological Semimetals  

NASA Astrophysics Data System (ADS)

Weyl semimetals are three-dimensional crystalline systems where pairs of bands touch at points in momentum space, termed Weyl nodes, that are characterized by a definite topological charge: the chirality. Consequently, they exhibit the Adler-Bell-Jackiw anomaly, which in this condensed-matter realization implies that the application of parallel electric (E) and magnetic (B) fields pumps electrons between nodes of opposite chirality at a rate proportional to E .B. We argue that this pumping is measurable via nonlocal transport experiments, in the limit of weak internode scattering. Specifically, we show that as a consequence of the anomaly, applying a local magnetic field parallel to an injected current induces a valley imbalance that diffuses over long distances. A probe magnetic field can then convert this imbalance into a measurable voltage drop far from source and drain. Such nonlocal transport vanishes when the injected current and magnetic field are orthogonal and therefore serves as a test of the chiral anomaly. We further demonstrate that a similar effect should also characterize Dirac semimetals—recently reported to have been observed in experiments—where the coexistence of a pair of Weyl nodes at a single point in the Brillouin zone is protected by a crystal symmetry. Since the nodes are analogous to valley degrees of freedom in semiconductors, the existence of the anomaly suggests that valley currents in three-dimensional topological semimetals can be controlled using electric fields, which has potential practical "valleytronic" applications.

Parameswaran, S. A.; Grover, T.; Abanin, D. A.; Pesin, D. A.; Vishwanath, A.

2014-07-01

269

Soliton Topology versus Discrete Symmetry in Optical Lattices Yaroslav V. Kartashov,1  

E-print Network

charges of solitons. We set a general ``charge rule'' using group-theory techniques, which holds for all, such vortices can be made stable in contrast to their ring-shaped counterparts in uniform focusing media. Recently, vortices having unit topological charge have been experimentally observed in optically induced

Fernández de Córdoba, Pedro

270

BRST QUANTIZATION OF NON-ABELIAN BF TOPOLOGICAL THEORIES  

E-print Network

The off-shell nilpotent BRST charge and the BRST invariant effective action for non-abelian BF topological theories over D-dimensional manifolds are explicitly constructed. These theories have the feature of being reducible with exactly D-3 stages of reducibility. The adequate extended phase space including the different levels of ghosts for ghosts is explicitly obtained. Using the structure of the resulting BRST charge we show that for topological BF theories the semi-classical approximation completely describes the quantum theory. The independence of the partition function on the metric also follows from our explicit construction in a straightforward way.

M. I. Caicedo; R. Gianvittorio; A. Restuccia; J. Stephany

1995-02-24

271

Polydispersity-driven topological defects as order-restoring excitations  

PubMed Central

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

272

Topological discretization of bosonic strings  

Microsoft Academic Search

We apply the method of topological quantization to obtain the bosonic string topological spectrum propagating on a flat background. We define the classical configuration of the system, and construct the corresponding principal fiber bundle (pfb) that uniquely represents it. The topological spectrum is defined through the characteristic class of the pfb. We find explicit expressions for the topological spectrum for

Gustavo Arciniega; Francisco Nettel; Leonardo Patiño; Hernando Quevedo

2011-01-01

273

Quantum Circuit Model Topological Model  

E-print Network

Quantum Circuit Model Topological Model Comparison of Models Topological Quantum Computation Eric Rowell Texas A&M University October 2010 Eric Rowell Topological Quantum Computation #12;Quantum Circuit Model Topological Model Comparison of Models Outline 1 Quantum Circuit Model Gates, Circuits

Rowell, Eric C.

274

42 CFR 405.509 - Determining the inflation-indexed charge.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Determining the inflation-indexed charge. 405.509... § 405.509 Determining the inflation-indexed charge. (a) Definition. For purposes of this section, inflation-indexed charge means...

2013-10-01

275

42 CFR 405.509 - Determining the inflation-indexed charge.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Determining the inflation-indexed charge. 405.509... § 405.509 Determining the inflation-indexed charge. (a) Definition. For purposes of this section, inflation-indexed charge means...

2011-10-01

276

42 CFR 405.509 - Determining the inflation-indexed charge.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Determining the inflation-indexed charge. 405.509... § 405.509 Determining the inflation-indexed charge. (a) Definition. For purposes of this section, inflation-indexed charge means...

2012-10-01

277

42 CFR 405.509 - Determining the inflation-indexed charge.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 false Determining the inflation-indexed charge. 405.509... § 405.509 Determining the inflation-indexed charge. (a) Definition. For purposes of this section, inflation-indexed charge means...

2014-10-01

278

42 CFR 405.509 - Determining the inflation-indexed charge.  

Code of Federal Regulations, 2010 CFR

...false Determining the inflation-indexed charge. 405.509 Section 405.509 Public...DISABLED Criteria for Determining Reasonable Charges § 405.509 Determining the inflation-indexed charge. (a) Definition. For...

2010-10-01

279

Topological quantization of mass in extended gauge theories with a monopole  

Microsoft Academic Search

Alvarez's treatment of topological charge quantization is generalized to include extended objects like the Dirac string in the presence of a magnetic pole. We rederive the topological mass quantization of the Abelian gauge field in (2+1)-dimensional spacetime previously derived by Henneaux and Teitelboim. A plausible argument is given for the general 2p + 1 cases in which the present method

H. B. Gao; Y. H. Gao; M. Li

1987-01-01

280

Topological subsystem codes  

E-print Network

We introduce a family of two-dimensional (2D) topological subsystem quantum error-correcting codes. The gauge group is generated by two-local Pauli operators, so that two-local measurements are enough to recover the error ...

Bombin, Hector

281

Combinational Reasoning of Quantitative Fuzzy Topological Relations for Simple Fuzzy Regions  

PubMed Central

In recent years, formalization and reasoning of topological relations have become a hot topic as a means to generate knowledge about the relations between spatial objects at the conceptual and geometrical levels. These mechanisms have been widely used in spatial data query, spatial data mining, evaluation of equivalence and similarity in a spatial scene, as well as for consistency assessment of the topological relations of multi-resolution spatial databases. The concept of computational fuzzy topological space is applied to simple fuzzy regions to efficiently and more accurately solve fuzzy topological relations. Thus, extending the existing research and improving upon the previous work, this paper presents a new method to describe fuzzy topological relations between simple spatial regions in Geographic Information Sciences (GIS) and Artificial Intelligence (AI). Firstly, we propose a new definition for simple fuzzy line segments and simple fuzzy regions based on the computational fuzzy topology. And then, based on the new definitions, we also propose a new combinational reasoning method to compute the topological relations between simple fuzzy regions, moreover, this study has discovered that there are (1) 23 different topological relations between a simple crisp region and a simple fuzzy region; (2) 152 different topological relations between two simple fuzzy regions. In the end, we have discussed some examples to demonstrate the validity of the new method, through comparisons with existing fuzzy models, we showed that the proposed method can compute more than the existing models, as it is more expressive than the existing fuzzy models. PMID:25775452

Liu, Bo; Li, Dajun; Xia, Yuanping; Ruan, Jian; Xu, Lili; Wu, Huanyi

2015-01-01

282

Combinational reasoning of quantitative fuzzy topological relations for simple fuzzy regions.  

PubMed

In recent years, formalization and reasoning of topological relations have become a hot topic as a means to generate knowledge about the relations between spatial objects at the conceptual and geometrical levels. These mechanisms have been widely used in spatial data query, spatial data mining, evaluation of equivalence and similarity in a spatial scene, as well as for consistency assessment of the topological relations of multi-resolution spatial databases. The concept of computational fuzzy topological space is applied to simple fuzzy regions to efficiently and more accurately solve fuzzy topological relations. Thus, extending the existing research and improving upon the previous work, this paper presents a new method to describe fuzzy topological relations between simple spatial regions in Geographic Information Sciences (GIS) and Artificial Intelligence (AI). Firstly, we propose a new definition for simple fuzzy line segments and simple fuzzy regions based on the computational fuzzy topology. And then, based on the new definitions, we also propose a new combinational reasoning method to compute the topological relations between simple fuzzy regions, moreover, this study has discovered that there are (1) 23 different topological relations between a simple crisp region and a simple fuzzy region; (2) 152 different topological relations between two simple fuzzy regions. In the end, we have discussed some examples to demonstrate the validity of the new method, through comparisons with existing fuzzy models, we showed that the proposed method can compute more than the existing models, as it is more expressive than the existing fuzzy models. PMID:25775452

Liu, Bo; Li, Dajun; Xia, Yuanping; Ruan, Jian; Xu, Lili; Wu, Huanyi

2015-01-01

283

Electrically tunable surface-to-bulk coherent coupling in topological insulator thin films  

E-print Network

We study coherent electronic transport in charge-density-tunable microdevices patterned from thin films of the topological insulator (TI) Bi[subscript 2]Se[subscript 3]. The devices exhibit pronounced electric field effect, ...

Steinberg, Hadar

284

Physics of Three-Dimensional Bosonic Topological Insulators: Surface-Deconfined Criticality and Quantized Magnetoelectric Effect  

E-print Network

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

285

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

286

Polariton Z Topological Insulator  

NASA Astrophysics Data System (ADS)

We demonstrate that honeycomb arrays of microcavity pillars behave as an optical-frequency two-dimensional photonic topological insulator. We show that the interplay between the photonic spin-orbit coupling natively present in this system and the Zeeman splitting of exciton polaritons in external magnetic fields leads to the opening of a nontrivial gap characterized by a C =±2 set of band Chern numbers and to the formation of topologically protected one-way edge states.

Nalitov, A. V.; Solnyshkov, D. D.; Malpuech, G.

2015-03-01

287

Superconductors with Topological Order  

E-print Network

We propose a mechanism of superconductivity in which the order of the ground state does not arise from the usual Landau mechanism of spontaneous symmetry breaking but is rather of topological origin. The low-energy effective theory is formulated in terms of emerging gauge fields rather than a local order parameter and the ground state is degenerate on topologically non-trivial manifolds. The simplest example of this mechanism of superconductivty is concretely realized as global superconductivty in Josephson junction arrays.

M. C. Diamantini; P. Sodano; C. A. Trugenberger

2005-11-18

288

Polariton z topological insulator.  

PubMed

We demonstrate that honeycomb arrays of microcavity pillars behave as an optical-frequency two-dimensional photonic topological insulator. We show that the interplay between the photonic spin-orbit coupling natively present in this system and the Zeeman splitting of exciton polaritons in external magnetic fields leads to the opening of a nontrivial gap characterized by a C=±2 set of band Chern numbers and to the formation of topologically protected one-way edge states. PMID:25839295

Nalitov, A V; Solnyshkov, D D; Malpuech, G

2015-03-20

289

Mean topological dimension  

Microsoft Academic Search

In this paper we present some results and applications of a new invariant for dynamical systems that can be viewed as a dynamical\\u000a analogue of topological dimension. This invariant has been introduced by M. Gromov, and enables one to assign a meaningful\\u000a quantity to dynamical systems of infinite topological dimension and entropy. We also develop an alternative approach that\\u000a is

Elon Lindenstrauss; Benjamin Weiss

2000-01-01

290

Topology of Density Matrices  

E-print Network

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

291

Order Topology and Frink Ideal Topology of Effect Algebras  

E-print Network

In this paper, the following results are proved: (1) $ $ If $E$ is a complete atomic lattice effect algebra, then $E$ is (o)-continuous iff $E$ is order-topological iff $E$ is totally order-disconnected iff $E$ is algebraic. (2) $ $ If $E$ is a complete atomic distributive lattice effect algebra, then its Frink ideal topology $\\tau_{id}$ is Hausdorff topology and $\\tau_{id}$ is finer than its order topology $\\tau_{o}$, and $\\tau_{id}=\\tau_o$ iff 1 is finite iff every element of $E$ is finite iff $\\tau_{id}$ and $\\tau_o$ are both discrete topologies. (3) $ $ If $E$ is a complete (o)-continuous lattice effect algebra and the operation $\\oplus$ is order topology $\\tau_o$ continuous, then its order topology $\\tau_{o}$ is Hausdorff topology. (4) $ $ If $E$ is a (o)-continuous complete atomic lattice effect algebra, then $\\oplus$ is order topology continuous.

Lei Qiang; Wu Junde; Li Ronglu

2009-12-15

292

Information processing with topologically protected vortex memories in exciton-polariton condensates  

NASA Astrophysics Data System (ADS)

We show that in a nonequilibrium system of an exciton-polariton condensate, where polaritons are generated from incoherent pumping, a ring-shaped pump allows for stationary vortex memory elements of topological charge m =1 or m =-1. Using simple potential guides we can choose whether to copy the same charge or invert it onto another spatially separate ring pump. Such manipulation of binary information opens the possibility of a new type of processing using vortices as topologically protected memory components.

Sigurdsson, H.; Egorov, O. A.; Ma, X.; Shelykh, I. A.; Liew, T. C. H.

2014-07-01

293

Topological Photonic States  

NASA Astrophysics Data System (ADS)

As exotic phenomena in optics, topological states in photonic crystals have drawn much attention due to their fundamental significance and great potential applications. Because of the broken time-reversal symmetry under the influence of an external magnetic field, the photonic crystals composed of magneto-optical materials will lead to the degeneracy lifting and show particular topological characters of energy bands. The upper and lower bulk bands have nonzero integer topological numbers. The gapless edge states can be realized to connect two bulk states. This topological photonic states originated from the topological property can be analogous to the integer quantum Hall effect in an electronic system. The gapless edge state only possesses a single sign of gradient in the whole Brillouin zone, and thus the group velocity is only in one direction leading to the one-way energy flow, which is robust to disorder and impurity due to the nontrivial topological nature of the corresponding electromagnetic states. Furthermore, this one-way edge state would cross the Brillouin center with nonzero group velocity, where the negative-zero-positive phase velocity can be used to realize some interesting phenomena such as tunneling and backward phase propagation. On the other hand, under the protection of time-reversal symmetry, a pair of gapless edge states can also be constructed by using magnetic-electric coupling meta-materials, exhibiting Fermion-like spin helix topological edge states, which can be regarded as an optical counterpart of topological insulator originating from the spin-orbit coupling. The aim of this article is to have a comprehensive review of recent research literatures published in this emerging field of photonic topological phenomena. Photonic topological states and their related phenomena are presented and analyzed, including the chiral edge states, polarization dependent transportation, unidirectional waveguide and nonreciprocal optical transmission, all of which might lead to novel applications such as one-way splitter, optical isolator and delay line. In addition, the possible prospect and development of related topics are also discussed.

He, Cheng; Lin, Liang; Sun, Xiao-Chen; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yan-Feng

2014-01-01

294

Seeing the magnetic monopole through the mirror of topological surface states  

SciTech Connect

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

295

FONO: a difficult case for theory. The ELF and ELI-D topological studies on the chemical bonding using correlated wavefunctions.  

PubMed

The complicated nature of the chemical bonding in cis and trans isomers of F-O-N=O is discussed based on the results obtained from the topological analysis of electron localization function (?) (ELF), electron localizability index (Y(D)(?)), and electron density (?). The calculations have been performed for correlated wavefunctions using the CCSD and CASSCF methods. The F-O1 bond with non-bonding basins, V(F) and V(')(O1), belongs to the protocovalent type (?,Y(D)(?)) and its total population ranges between 0.2 and 0.4e. The central N-O1 bond in the cis form is protocovalent (?, Y(D)(?)) with two basins, V(N) and V(O1). The total population oscillates between 0.7 and 0.9e. In the trans isomer, topology of ELF depends on used method. At the CCSD level only one non-bonding basin, V(N), is observed (?). Its population is about 0.5e. According to the definition of a heteronuclear charge-shift (CS) bond, only N-O1 bond in trans-FONO belongs to the CS class. A relation between ?- and ?-topology and N-O1 bond length is discussed. PMID:23574233

Berski, Slawomir; Gordon, Agnieszka J; Latajka, Zdzislaw

2013-04-01

296

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

297

General covariance, topological quantum field theories and fractional statistics  

SciTech Connect

Topological quantum field theories and fractional statistics are both defined in multiply connected manifolds. The authors study the relationship between both theories in 2 + 1 dimensions and the authors show that, due to the multiply-connected character of the manifold, the propagator for any quantum (field) theory always contains a first order pole that can be identified with a physical excitation with fractional spin. The article starts by reviewing the definition of general covariance in the Hamiltonian formalism, the gauge-fixing problem and the quantization following the lines of Batalin, Fradkin and Vilkovisky. The BRST-BFV quantization is reviewed in order to understand the topological approach proposed here.

Gamboa, J. (Departamento de Fiscia Teorica, Universidad de Zaragoza, Zaragoza 50009 (ES))

1992-01-20

298

The electric charge and magnetic moment of neutral fundamental particles  

E-print Network

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

299

Topological Insulators Avoid the Parity Anomaly  

E-print Network

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

300

Pair Production of Topological anti de Sitter Black Holes  

E-print Network

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

301

Topological quantization of current in quantum tunnel contacts  

Microsoft Academic Search

It is shown that an account of the Berry phase (a topological $\\\\theta$-term) together with a dissipative term in the effective action $S[\\\\phi]$ of the tunnel contacts induces a strong quantization of the tunnel current at low temperatures. This phenomenon like the Coulomb blockade reflects a discrete charge structure of the quantum shot noise and can ensure a quantization of

S. A. Bulgadaev

2006-01-01

302

Extended topological defects as sources and outlets of dislocations in spherical hexagonal crystals  

NASA Astrophysics Data System (ADS)

Extended topological defects (ETDs) arising in spherical hexagonal crystals due to their curvature are considered. These prevalent defects carry a unit total topological charge and are surrounded by scalene pentagonal boundaries. Topological peculiarities of reactions between ETDs and dislocations are considered. Similarly to boundaries of the usual planar crystalline order the ETDs emit and absorb the dislocations without preservation of their dislocational charge. Dislocations located inside the ETD area lose it and the enforced ETD decay can proceed in different ways without conservation of the total Burgers vector of the dislocations emitted.

Roshal, D. S.; Petrov, K. Yu.; Myasnikova, A. E.; Rochal, S. B.

2014-04-01

303

Manifestations of topological effects in graphene  

E-print Network

Graphene is a monoatomic layer of graphite with Carbon atoms arranged in a two dimensional honeycomb lattice configuration. It has been known for more than sixty years that the electronic structure of graphene can be modelled by two-dimensional massless relativistic fermions. This property gives rise to numerous applications, both in applied sciences and in theoretical physics. Electronic circuits made out of graphene could take advantage of its high electron mobility that is witnessed even at room temperature. In the theoretical domain the Dirac-like behavior of graphene can simulate high energy effects, such as the relativistic Klein paradox. Even more surprisingly, topological effects can be encoded in graphene such as the generation of vortices, charge fractionalization and the emergence of anyons. The impact of the topological effects on graphene's electronic properties can be elegantly described by the Atiyah-Singer index theorem. Here we present a pedagogical encounter of this theorem and review its various applications to graphene. A direct consequence of the index theorem is charge fractionalization that is usually known from the fractional quantum Hall effect. The charge fractionalization gives rise to the exciting possibility of realizing graphene based anyons that unlike bosons or fermions exhibit fractional statistics. Besides being of theoretical interest, anyons are a strong candidate for performing error free quantum information processing.

Jiannis K. Pachos

2008-12-05

304

Topology improves phylogenetic motif functional site predictions.  

PubMed

Prediction of protein functional sites from sequence-derived data remains an open bioinformatics problem. We have developed a phylogenetic motif (PM) functional site prediction approach that identifies functional sites from alignment fragments that parallel the evolutionary patterns of the family. In our approach, PMs are identified by comparing tree topologies of each alignment fragment to that of the complete phylogeny. Herein, we bypass the phylogenetic reconstruction step and identify PMs directly from distance matrix comparisons. In order to optimize the new algorithm, we consider three different distance matrices and 13 different matrix similarity scores. We assess the performance of the various approaches on a structurally nonredundant data set that includes three types of functional site definitions. Without exception, the predictive power of the original approach outperforms the distance matrix variants. While the distance matrix methods fail to improve upon the original approach, our results are important because they clearly demonstrate that the improved predictive power is based on the topological comparisons. Meaning that phylogenetic trees are a straightforward, yet powerful way to improve functional site prediction accuracy. While complementary studies have shown that topology improves predictions of protein-protein interactions, this report represents the first demonstration that trees improve functional site predictions as well. PMID:21071810

Kc, Dukka B; Livesay, Dennis R

2011-01-01

305

Dilute magnetic topological semiconductors  

NASA Astrophysics Data System (ADS)

Replacing semiconductors with topological insulators, we propose the problem of dilute magnetic topological semiconductors. Performing the renormalization group analysis for an effective field theory, where doped magnetic impurities give rise to a spatially modulated random axion term, we find a novel insulator-metal transition from either a topological or band insulating phase to an inhomogeneously distributed Weyl metallic state with such insulating islands, where extremely broad distributions of ferromagnetic clusters combined with strong spin-orbit interactions are responsible for the emergence of randomly distributed Weyl metallic islands. Since electromagnetic properties in a Weyl metal are described by axion electrodynamics, the role of random axion electrodynamics in transport phenomena casts an interesting problem beyond the physics of percolation in conventional disorder-driven metal-insulator transitions.

Kim, Kyoung-Min; Jho, Yong-Soo; Kim, Ki-Seok

2015-03-01

306

Bibliography. P. Alexandroff, Elementary concepts of topology,  

E-print Network

Bibliography. · P. Alexandroff, Elementary concepts of topology, Dover (1961) · C.W. Baker, Introduction to Topology, Brown (1991) · M. Barnsley, Fractals everywhere, Academic Press (1988) · N. Bourbaki, Elements of Mathematics: General topology, Addison Wesley Verlag (1966) · J. Dugundji, Topology, Ally

Johannson, Klaus

307

Multidimensional Topological Foam  

E-print Network

Multidimensional cosmological model with the topology M=RxM_1xM_2x...xM_n where M_i (i=1,... ,n) undergo a chain splitting into arbitrary number of compact spaces is considered. It is shown that equations of motion can be solved exactly because they depend only on the effective curvatures and dimensions and "forget" about inner topological structure. It is proved that effective cosmological action for the model with n=1 in the case of infinite splitting of the internal space coincides with the tree-level effective action for a bosonic string.

A. Zhuk

1997-01-15

308

COVER IMAGE Topological quantum computation  

E-print Network

COVER IMAGE Topological quantum computation schemes -- in which quantum information is stored non of one- dimensional semiconducting wires should bring topological quantum computers a step closer 376 Quantum metrology: Beauty and the noisy beast Lorenzo Maccone and Vittorio Giovannetti 377

Loss, Daniel

309

Topological Quantum Computing Jacob Colbert  

E-print Network

Topological Quantum Computing Jacob Colbert 3/5/2011 Contents 1 Introduction 1 2 Typical Quantum Computing 2 2.1 What is Quantum Computing? . . . . . . . . . . . . . . . . . . . . . . . 2 2.2 Quantum Error Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 Topological Quantum Computing

Rosner, Jonathan L.

310

The Topology of Branching Universes  

E-print Network

The purpose of this paper is to survey the possible topologies of branching space-times, and, in particular, to refute the popular notion in the literature that a branching space-time requires a non-Hausdorff topology.

Gordon McCabe

2005-05-30

311

Communication: An approximation to Bader's topological atom  

NASA Astrophysics Data System (ADS)

A new, more flexible definition of fuzzy Voronoi cells is proposed as a computationally efficient alternative to Bader's Quantum Theory of Atoms in Molecules (QTAIM) partitioning of the physical space for large-scale routine calculations. The new fuzzy scheme provides atomic charges, delocalization indices, and molecular energy components very close to those obtained using QTAIM. The method is flexible enough to either ignore the presence of spurious non-nuclear attractors or to readily incorporate them by introducing additional fuzzy Voronoi cells.

Salvador, Pedro; Ramos-Cordoba, Eloy

2013-08-01

312

Take Charge!  

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,

313

Symmetry enforced non-Abelian topological order at the surface of a topological insulator  

NASA Astrophysics Data System (ADS)

The surfaces of three-dimensional topological insulators (3D TIs) are generally described as Dirac metals, with a single Dirac cone. It was previously believed that a gapped surface implied breaking of either time-reversal T or U(1) charge conservation symmetry. Here, we discuss a possibility in the presence of interactions, a surface phase that preserves all symmetries but is nevertheless gapped and insulating. Then, the surface must develop topological order of a kind that can not be realized in a two-dimensional (2D) system with the same symmetries. We discuss candidate surface states, non-Abelian quantum Hall states which, when realized in 2D, have ?xy=1/2 and hence break T symmetry. However, by constructing an exactly soluble 3D lattice model, we show they can be realized as T-symmetric surface states. The corresponding 3D phases are confined, and have ? =? magnetoelectric response. Two candidate states have the same 12-particle topological order, the (Read-Moore) Pfaffian state with the neutral sector reversed, which we term T-Pfaffian topological order, but differ in their T transformation. Although we are unable to connect either of these states directly to the superconducting TI surface, we argue that one of them describes the 3D TI surface, while the other differs from it by a bosonic topological phase. We also discuss the 24-particle Pfaffian-antisemion topological order (which can be connected to the superconducting TI surface) and demonstrate that it can be realized as a T-symmetric surface state.

Chen, Xie; Fidkowski, Lukasz; Vishwanath, Ashvin

2014-04-01

314

Quantum foam and topological strings  

Microsoft Academic Search

We find an interpretation of the recent connection found between topological strings on Calabi-Yau threefolds and crystal melting: Summing over statistical mechanical configuration of melting crystal is equivalent to a quantum gravitational path integral involving fluctuations of Kähler geometry and topology. We show how the limit shape of the melting crystal emerges as the average geometry and topology of the

Amer Iqbal; Cumrun Vafa; Nikita Nekrasov; Andrei Okounkov

2008-01-01

315

Topological Aspects of Liquid Crystals  

Microsoft Academic Search

Using f-mapping method and topological current theory, the properties and behaviors of disclination points in three-dimensional liquid crystals are studied. By introducing the strength density and the topological current of many disclination points, the total disclination strength is topologically quantized by the Hopf indices and Brouwer degrees at the singularities of the general director field when the Jacobian determinant of

Guo-Hong Yang; Hui Zhang; Yi-Shi Duan

2002-01-01

316

Topological censorship and chronology protection  

E-print Network

Over the past two decades, substantial efforts have been made to understand the way in which physics enforces the ordinary topology and causal structure that we observe, from subnuclear to cosmological scales. We review the status of topological censorship and the topology of event horizons; chronology protection in classical and semiclassical gravity; and related progress in establishing quantum energy inequalities.

John L. Friedman; Atsushi Higuchi

2008-06-03

317

Computational Topology for Geometric Design  

E-print Network

"mi03 2005/ page i i i i i i i i Computational Topology for Geometric Design and Molecular Design Edward L. F. Moore , Thomas J. Peters Abstract The nascent field of computational topology holds great. Commercial CAGD packages depend upon complementary geometric and topological algorithms. The emergence of geo

Peters, Thomas J.

318

An Introduction to Finitesimal Topology #  

E-print Network

An Introduction to Finitesimal Topology # M.Kegelmann, P.Selinger March 27, 1992 1 Motivation Since with the complex notions of infinite topological spaces, the authors hope that this humble exposition will serve into the depths of classical topology. Of course we assume some familiarity with basic concepts like the notions

Selinger, Peter

319

Topology with Dynamical Overlap Fermions  

E-print Network

We perform dynamical QCD simulations with $n_f=2$ overlap fermions by hybrid Monte-Carlo method on $6^4$ to $8^3\\times 16$ lattices. We study the problem of topological sector changing. A new method is proposed which works without topological sector changes. We use this new method to determine the topological susceptibility at various quark masses.

G. I. Egri; Z. Fodor; S. D. Katz; K. K. Szabo

2005-10-28

320

An Introduction to Finitesimal Topology  

E-print Network

An Introduction to Finitesimal Topology M.Kegelmann, P.Selinger March 27, 1992 1 Motivation Since with the complex notions of infinite topological spaces, the authors hope that this humble exposition will serve into the depths of classical topology. Of course we assume some familiarity with basic concepts like the notions

Selinger, Peter

321

Topology of Document Retrieval Systems.  

ERIC Educational Resources Information Center

Explains the use of a topological structure to examine the closeness between documents in retrieval systems and analyzes the topological structure of a vector-space model, a fuzzy-set model, an extended Boolean model, a probabilistic model, and a TIRS (Topological Information Retrieval System) model. Proofs for the results are appended. (17…

Everett, Daniel M.; Cater, Steven C.

1992-01-01

322

Topological Catastrophe and Isostructural Phase Transition in Calcium  

NASA Astrophysics Data System (ADS)

We predict a quantum phase transition in fcc Ca under hydrostatic pressure. Using density functional theory, we find, at pressures below 80 kbar, the topology of the electron charge density is characterized by nearest neighbor atoms connected through bifurcated bond paths and deep minima in the octahedral holes. At pressures above 80 kbar, the atoms bond through non-nuclear maxima that form in the octahedral holes. This topological change in the charge density softens the C' elastic modulus of fcc Ca, while C44 remains unchanged. We propose an order parameter based on applying Morse theory to the charge density, and we show that near the critical point it follows the expected mean-field scaling law with reduced pressure.

Jones, Travis E.; Eberhart, Mark E.; Clougherty, Dennis P.

2010-12-01

323

Topological quantum field theory  

Microsoft Academic Search

A twisted version of four dimensional supersymmetric gauge theory is formulated. The model, which refines a nonrelativistic treatment by Atiyah, appears to underlie many recent developments in topology of low dimensional manifolds; the Donaldson polynomial invariants of four manifolds and the Floer groups of three manifolds appear naturally. The model may also be interesting from a physical viewpoint; it is

Edward Witten

1988-01-01

324

An Invitation to Topology.  

ERIC Educational Resources Information Center

Describes two sets of activities designed to stimulate thinking skills and to bring some topological aspects into the mathematics curriculum. One set explores Mobius strips; the other set deals with tori. The activities are suitable for students in fourth through eighth grades. (JN)

Poggi, Jeanlee M.

1985-01-01

325

Topological Open Membranes  

Microsoft Academic Search

We study topological open membranes of BF type in a manifest BV formalism. Our main interest is the effect of the bulk deformations on the algebra of boundary operators. This forms a homotopy Lie algebra, which can be understood in terms of a closed string field theory. The simplest models are associated to quasi-Lie bialgebras and are of Chern-Simons type.

Christiaan Hofman; Jae-Suk Park

2002-01-01

326

Topological Evolution of Surfaces  

Microsoft Academic Search

This paper presents a framework for generating smooth- looking transformations between pairs of surfaces that may differ in topology. The user controls the transforma- tion by specifying a sparse control mesh on each surface and by associating each face in one control mesh with a corresponding face in the other. The algorithm builds a transformation from this information in two

Douglas Decarlo; Jean H. Gallier

1996-01-01

327

Elementary Topology Problem Textbook  

E-print Network

#12;Dedicated to the memory of Vladimir Abramovich Rokhlin (1919­1984) ­ our teacher #12;Contents 41x. Classification of Covering Spaces 207 Chapter IX. Cellular Techniques 213 42. Cellular Spaces 213 43x. Topological Properties of Cellular Spaces 220 44. Cellular Constructions 222 45. One

Viro, Oleg

328

Topological Trigger Developments  

E-print Network

The main b-physics trigger algorithm used by the LHCb experiment is the so-called topological trigger. The topological trigger selects vertices which are a) detached from the primary proton-proton collision and b) compatible with coming from the decay of a b-hadron. In the LHC Run 1, this trigger utilized a custom boosted decision tree algorithm, selected an almost 100% pure sample of b-hadrons with a typical efficiency of 60-70%, and its output was used in about 60% of LHCb papers. This talk presents studies carried out to optimize the topological trigger for LHC Run 2. In particular, we have carried out a detailed comparison of various machine learning classifier algorithms, e.g., AdaBoost, MatrixNet and uBoost. The topological trigger algorithm is designed to select all "interesting" decays of b-hadrons, but cannot be trained on every such decay. Studies have therefore been performed to determine how to optimize the performance of the classification algorithm on decays not used in the training. These inclu...

Likhomanenko, Tatiana

2015-01-01

329

Spectroscopy of Cosmic topology  

E-print Network

Einstein's theory of gravitation that governs the geometry of space-time, coupled with spectacular advance in cosmological observations, promises to deliver a `standard model' of cosmology in the near future. However, local geometry of space constrains, but does not dictate the topology of the cosmos. hence, Cosmic topology has remained an enigmatic aspect of the `standard model' of cosmology. Recent advance in the quantity and quality of observations has brought this issue within the realm of observational query. The breakdown of statistical homogeneity and isotropy of cosmic perturbations is a generic consequence of non trivial cosmic topology arising from to the imposed `crystallographic' periodicity on the eigenstates of the Laplacian. The sky maps of Cosmic Microwave Background (CMB) anisotropy and polarization most promising observations that would carry signatures of a violation of statistical isotropy and homogeneity. Hence, a measurable spectroscopy of cosmic topology is made possible using the Bipolar power spectrum (BiPS) of the temperature and polarization that quantifies violation of statistical isotropy.

Tarun Souradeep

2006-09-07

330

Homotopy Theory of Strong and Weak Topological Insulators  

E-print Network

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

331

Lawson topology of the space of formal balls and the hyperbolic topology  

E-print Network

Lawson topology of the space of formal balls and the hyperbolic topology Hideki Tsuiki a,,1 investigate the topological structures of BX, in particular the relations between the Lawson topology and the product topology. We show that the Lawson topology coincides with the product topology if (X, d

Tsuiki, Hideki

332

Conserved charges in 3D gravity  

SciTech Connect

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

333

Interim President R. Bowen Loftin requested that the Task Force on Enlightened and Shared Governance continue to pursue its initial charge from former President Elsa A. Murano to: clarify and reach consensus on the definition of enlightened and  

E-print Network

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

334

Flat bands in topological media  

E-print Network

Topological media are systems whose properties are protected by topology and thus are robust to deformations of the system. In topological insulators and superconductors the bulk-surface and bulk-vortex correspondence gives rise to the gapless Weyl, Dirac or Majorana fermions on the surface of the system and inside vortex cores. Here we show that in gapless topological media, the bulk-surface and bulk-vortex correspondence is more effective: it produces topologically protected gapless fermions without dispersion -- the flat band. Fermion zero modes forming the flat band are localized on the surface of topological media with protected nodal lines and in the vortex core in systems with topologically protected Fermi points (Weyl points). Flat band has an extremely singular density of states, and we show that this property may give rise in particular to surface superconductivity which could exist even at room temperature.

T. T. Heikkila; N. B. Kopnin; G. E. Volovik

2011-07-26

335

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

336

Chiral Nonlinear sigma models as models for topological superconductivity.  

PubMed

We study the mechanism of topological superconductivity in a hierarchical chain of chiral nonlinear sigma models (models of current algebra) in one, two, and three spatial dimensions. The models illustrate how the 1D Fröhlich's ideal conductivity extends to a genuine superconductivity in dimensions higher than one. The mechanism is based on the fact that a pointlike topological soliton carries an electric charge. We discuss a flux quantization mechanism and show that it is essentially a generalization of the persistent current phenomenon, known in quantum wires. We also discuss why the superconducting state is stable in the presence of a weak disorder. PMID:11178073

Abanov, A G; Wiegmann, P B

2001-02-12

337

Seiberg-Witten Instability of Various Topological Black Holes  

NASA Astrophysics Data System (ADS)

We review the Seiberg-Witten instability of topological black holes in Anti-de Sitter space due to nucleation of brane-anti-brane pairs. We start with black holes in general relativity, and then proceed to discuss the peculiar property of topological black holes in Ho?ava-Lifshitz gravity - they have instabilities that occur at only finite range of distance away from the horizon. This behavior is not unique to black holes in Ho?ava-Lifshitz theory, as it is also found in the relatively simple systems of charged black hole with dilaton hair that arise in low energy limit of string theory.

Ong, Yen Chin; Chen, Pisin

2015-01-01

338

Optically engineering the topological properties of a spin Hall insulator.  

PubMed

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

339

CHARGE IMBALANCE  

SciTech Connect

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

340

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

E-print Network

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

341

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

2011-12-01

342

New Precharge and Submodule Capacitor Voltage Balancing Topologies of Modular Multilevel Converter for VSC-HVDC Application  

Microsoft Academic Search

This paper presents two novel topologies on precharge and submodule capacitor voltage balancing schemes of Modular Multilevel Converter (MMC) for VSC-HVDC application respectively. Firstly, A traditional precharge process of MMC was modeled in PSCAD\\/EMTDC, its drawbacks were summarized and a novel topology was proposed based on submodules charged synchronously; Secondly, we analyzed the principles of a traditional submodule capacitor voltage

Jianzhong Xu; Chengyong Zhao; Baoshun Zhang; Li Lu

2011-01-01

343

Internal Charging  

NASA Technical Reports Server (NTRS)

(1) High energy (>100keV) electrons penetrate spacecraft walls and accumulate in dielectrics or isolated conductors; (2) Threat environment is energetic electrons with sufficient flux to charge circuit boards, cable insulation, and ungrounded metal faster than charge can dissipate; (3) Accumulating charge density generates electric fields in excess of material breakdown strenght resulting in electrostatic discharge; and (4) System impact is material damage, discharge currents inside of spacecraft Faraday cage on or near critical circuitry, and RF noise.

Minow, Joseph I.

2014-01-01

344

7 CFR 1925.2 - Definition of tax.  

Code of Federal Regulations, 2010 CFR

...Servicing § 1925.2 Definition of tax. For the purpose of this instruction, the word “tax” means all taxes, assessments, levies, irrigation and water charges or other similar obligations which are or will, on nonpayment, become a lien...

2010-01-01

345

7 CFR 1925.2 - Definition of tax.  

Code of Federal Regulations, 2011 CFR

...Servicing § 1925.2 Definition of tax. For the purpose of this instruction, the word “tax” means all taxes, assessments, levies, irrigation and water charges or other similar obligations which are or will, on nonpayment, become a lien...

2011-01-01

346

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

347

Network topology mapper  

DOEpatents

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

348

Topologically massive gauge theories  

SciTech Connect

Gauge vector and gravity models are studied in three-dimensional space-time, where novel, gauge invariant, P and T odd terms of topological origin give rise to masses for the gauge fields. In the vector case, the massless Maxwell excitation, which is spinless, becomes massive with spin 1. When interacting with fermions, the quantum theory is infrared and ultraviolet finite in perturbation theory. For non-Abelian models, topological considerations lead to a quantization condition on the dimensionless coupling constant-mass ratio. Ordinary Einstein gravity is trivial, but when augmented by our mass term, it acquires a propagating, massive, spin 2 mode. This theory is ghost-free and causal, although of third-derivative order. Quantum calculations are presented in both the Abelian and non-Abelian vector models, to exhibit some of the delicate aspects of infrared behavior, and regularization dependence. (c) 2000 Academic Press, Inc.

Deser, S. [Department of Physics, Brandeis University, Waltham, Massachusetts 02254 (United States)] [Department of Physics, Brandeis University, Waltham, Massachusetts 02254 (United States); Jackiw, R. [Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Templeton, S. [Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2000-04-10

349

Ectoplasm has no topology  

NASA Astrophysics Data System (ADS)

In a new approach to the theory of integration over Wess-Zumino supermanifolds, we suggest that a fundamental principle is their consistency with an "Ethereal Conjecture" that asserts the topology of the supermanifold must be generated essentially from its bosonic submanifold. This naturally leads to a theory of "ectoplasmic" integration based on super p-forms. One consequence of this approach is that the derivation of "density projection operators" becomes trivial in a number of supergravity theories.

Gates, S. James, Jr.

1999-03-01

350

Topological quantum computation  

Microsoft Academic Search

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

351

Geometry without Topology  

Microsoft Academic Search

The proper Euclidean geometry is considered to be metric space and described\\u000ain terms of only metric and finite metric subspaces (sigma-immanent\\u000adescription). Constructing the geometry, one does not use topology and\\u000atopological properties. For instance, the straight, passing through points A\\u000aand B, is defined as a set of such points R that the area S(A,B,R) of the\\u000atriangle

Yuri A. Rylov

2000-01-01

352

Topological confinement and superconductivity  

SciTech Connect

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

353

Topological invariant quintessence  

NASA Astrophysics Data System (ADS)

The issues of quintessence and cosmic acceleration can be discussed in the framework of F(R,G) theories of gravity where R is the Ricci curvature scalar and G is the Gauss-Bonnet topological invariant. It is possible to show that such an approach exhausts all the curvature content related to the Riemann tensor giving rise to a fully geometric approach to dark energy.

de Laurentis, Mariafelicia

2015-03-01

354

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

355

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

356

Topological proximity effect in a topological insulator hybrid.  

PubMed

It is well known that a topologically protected gapless state appears at an interface between a topological insulator and an ordinary insulator; however, the physics of the interface between a topological insulator and a metal has largely been left unexplored. Here we report a novel phenomenon termed topological proximity effect, which occurs between a metallic ultrathin film and a three-dimensional topological insulator. We study one bilayer of bismuth metal grown on the three-dimensional topological insulator material TlBiSe2, and by using spin- and angle-resolved photoemission spectroscopy, we found evidence that the topological Dirac-cone state migrates from the surface of TlBiSe2 to the attached one-bilayer Bi. We show that such a migration of the topological state occurs as a result of strong spin-dependent hybridization of the wave functions at the interface, which is also supported by our first-principles calculations. This discovery points to a new route to manipulating the topological properties of materials. PMID:25761780

Shoman, T; Takayama, A; Sato, T; Souma, S; Takahashi, T; Oguchi, T; Segawa, Kouji; Ando, Yoichi

2015-01-01

357

Topological proximity effect in a topological insulator hybrid  

NASA Astrophysics Data System (ADS)

It is well known that a topologically protected gapless state appears at an interface between a topological insulator and an ordinary insulator; however, the physics of the interface between a topological insulator and a metal has largely been left unexplored. Here we report a novel phenomenon termed topological proximity effect, which occurs between a metallic ultrathin film and a three-dimensional topological insulator. We study one bilayer of bismuth metal grown on the three-dimensional topological insulator material TlBiSe2, and by using spin- and angle-resolved photoemission spectroscopy, we found evidence that the topological Dirac-cone state migrates from the surface of TlBiSe2 to the attached one-bilayer Bi. We show that such a migration of the topological state occurs as a result of strong spin-dependent hybridization of the wave functions at the interface, which is also supported by our first-principles calculations. This discovery points to a new route to manipulating the topological properties of materials.

Shoman, T.; Takayama, A.; Sato, T.; Souma, S.; Takahashi, T.; Oguchi, T.; Segawa, Kouji; Ando, Yoichi

2015-03-01

358

The topological quantization and the branch process of the (k-1)-dimensional topological defects  

E-print Network

In the light of $\\phi$-mapping method and topological current theory, the topological structure and the topological quantization of arbitrary dimensional topological defects are obtained under the condition that the Jacobian $J(\\phi/v) \

Yishi Duan; Ying Jiang; Guohong Yang

1998-10-15

359

The topological quantization and the branch process of the (k-1)-dimensional topological defects  

Microsoft Academic Search

In the light of $\\\\phi$-mapping method and topological current theory, the topological structure and the topological quantization of arbitrary dimensional topological defects are obtained under the condition that the Jacobian $J(\\\\phi\\/v) \\\

Yishi Duan; Ying Jiang; Guohong Yang

1998-01-01

360

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

361

Tunable geometric phase of Dirac fermions in a topological junction  

NASA Astrophysics Data System (ADS)

We predict a tunable and nonadiabatic Berry phase effect of Dirac fermions, which is an electronic analog of the Pancharatnam phase of polarized light. The Berry phase occurs as a scattering phase shift in a single scattering event of transmission or reflection of Dirac fermions at a junction with a spatially nonuniform mass gap, unveiling the topological aspects of scattering of chiral Dirac fermions. This geometric phase plays different roles in solids as compared with the Pancharatnam phase in optics. It provides a unique approach of detecting the Chern number of the insulator side in a metal-insulator junction of Dirac fermions, implying a different type of bulk-edge correspondence at the boundary between a metal and an insulator. This phase also modifies the quantization rule of Dirac fermions, suggesting geometric-phase devices with nontrivial charge and spin transport such as a topological waveguide and a topological transistor.

Choi, Sang-Jun; Park, Sunghun; Sim, H.-S.

2013-04-01

362

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

363

A Framework for Computing Topological Network P. Van Mieghem , C. Doerr, H. Wang, J. Martin Hernandez, D. Hutchison, M. Karaliopoulos and R. E. Kooij  

E-print Network

1 A Framework for Computing Topological Network Robustness P. Van Mieghem , C. Doerr, H. Wang, J a definition and a framework to compute topological network robustness. I. INTRODUCTION Any network may on the network. Delft University of Technology, Faculty of Electrical Engineering, Math- ematics and Computer

Van Mieghem, Piet

364

The Topological Model Braid Group Representations  

E-print Network

The Topological Model Braid Group Representations Localizing Topological Quantum Computers Eric in Quantum Computation November 2010 Eric Rowell (joint work with Z. Wang) arXiv:1009.0241 Localizing Topological Quantum Computers #12;The Topological Model Braid Group Representations Outline 1 The Topological

Rowell, Eric C.

365

Visualizing vector field topology in fluid flows  

NASA Technical Reports Server (NTRS)

Methods of automating the analysis and display of vector field topology in general and flow topology in particular are discussed. Two-dimensional vector field topology is reviewed as the basis for the examination of topology in three-dimensional separated flows. The use of tangent surfaces and clipping in visualizing vector field topology in fluid flows is addressed.

Helman, James L.; Hesselink, Lambertus

1991-01-01

366

Measuring ISP topologies with rocketfuel  

Microsoft Academic Search

To date, realistic ISP topologies have not been accessible to the research community, leaving work that depends on topology on an uncertain footing. In this paper, we present new Internet mapping techniques that have enabled us to directly measure router-level ISP topologies. Our techniques reduce the number of required traces compared to a brute-force, all-to-all approach by three orders of

Neil T. Spring; Ratul Mahajan; David Wetherall

2002-01-01

367

5 CFR 2502.11 - Definitions.  

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

368

5 CFR 2502.11 - Definitions.  

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...

2012-01-01

369

40 CFR 98.438 - Definitions.  

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

370

40 CFR 98.438 - Definitions.  

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

371

40 CFR 98.438 - Definitions.  

Code of Federal Regulations, 2014 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...

2014-07-01

372

40 CFR 98.438 - Definitions.  

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

373

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

374

Detecting Communities Based on Network Topology  

PubMed Central

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

375

Switching a Normal Insulator into a Topological Insulator via Electric Field with Application to Phosphorene.  

PubMed

The study of topological insulators has generally involved search of materials that have this property as an innate quality, distinct from normal insulators. Here we focus on the possibility of converting a normal insulator into a topological one by application of an external electric field that shifts different bands by different energies and induces a specific band inversion, which leads to a topological state. Phosphorene is a two-dimensional (2D) material that can be isolated through mechanical exfoliation from layered black phosphorus, but unlike graphene and silicene, single-layer phosphorene has a large band gap (1.5-2.2 eV). Thus, it was unsuspected to exhibit band inversion and the ensuing topological insulator behavior. Using first-principles calculations with applied perpendicular electric field F? on few-layer phosphorene we predict a continuous transition from the normal insulator to a topological insulator and eventually to a metal as a function of F?. The tuning of topological behavior with electric field would lead to spin-separated, gapless edge states, that is, quantum spin Hall effect. This finding opens the possibility of converting normal insulating materials into topological ones via electric field and making a multifunctional "field effect topological transistor" that could manipulate simultaneously both spin and charge carrier. We use our results to formulate some design principles for looking for other 2D materials that could have such an electrical-induced topological transition. PMID:25607525

Liu, Qihang; Zhang, Xiuwen; Abdalla, L B; Fazzio, Adalberto; Zunger, Alex

2015-02-11

376

Topological spectrum of classical configurations  

SciTech Connect

For any classical field configuration or mechanical system with a finite number of degrees of freedom we introduce the concept of topological spectrum. It is based upon the assumption that for any classical configuration there exists a principle fiber bundle that contains all the physical and geometric information of the configuration. The topological spectrum follows from the investigation of the corresponding topological invariants. Examples are given which illustrate the procedure and the significance of the topological spectrum as a discretization relationship among the parameters that determine the physical meaning of classical configurations.

Nettel, Francisco; Quevedo, Hernando [Instituto de Ciencias Nucleares Universidad Nacional Autonoma de Mexico A.P. 70-543, Mexico D.F. 04510 (Mexico)

2007-11-14

377

Topological discretization of bosonic strings  

E-print Network

We apply the method of topological quantization to obtain the bosonic string topological spectrum propagating on a flat background. We define the classical configuration of the system, and construct the corresponding principal fiber bundle (pfb) that uniquely represents it. The topological spectrum is defined through the characteristic class of the pfb. We find explicit expressions for the topological spectrum for particular configurations of the bosonic strings on a Minkowski background and show that they lead to a discretization of the total energy of the system.

Gustavo Arciniega; Francisco Nettel; Leonardo Patiño; Hernando Quevedo

2011-11-09

378

Semi Compactness in Multiset Topology  

E-print Network

In this paper, we introduce and study the concepts of semi open SOM) and semi closed (SCM) M-sets in multiset topological spaces.With this generalization of the notions of open and closed sets in M-topology, we generalize the concept of compactness in M-topology as semi compactness. Further semi compactness is generalized as semi whole compactness, semi partial whole compactness and semi full compactness. Some characterizations of these compact spaces are studied in the setting of multiset theory. In each step, several remarks with proper justifications are provided taking the well existing theories of general topology as the base of our study.

J. Mahanta; D. Das

2014-11-21

379

WHEN IS THE ISBELL TOPOLOGY A GROUP TOPOLOGY? SZYMON DOLECKI AND FRDRIC MYNARD  

E-print Network

WHEN IS THE ISBELL TOPOLOGY A GROUP TOPOLOGY? SZYMON DOLECKI AND FRÉDÉRIC MYNARD Abstract. Conditions on a topological space X under which the space C(X; R) of continuous real-valued maps with the Isbell topology is a topological group (topological vector space) are investigated. It is proved

Dolecki, Szymon

380

Area D GEOMETRY AND TOPOLOGY Foundation in Geometry and Topology F4D1  

E-print Network

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

Sturm, Karl-Theodor

381

Weak gauge principle and electric charge quantization  

E-print Network

Starting from a weak gauge principle we give a new and critical revision of the argument leading to charge quantization on arbitrary spacetimes. The main differences of our approach with respect to previous works appear on spacetimes with non trivial torsion elements on its second integral cohomology group. We show that in these spacetimes there can be topologically non-trivial configurations of charged fields which do not imply charge quantization. However, the existence of a non-exact electromagnetic field always implies the quantization of charges. Another consequence of the theory for spacetimes with torsion is the fact that it gives rise to two natural quantization units that could be identified with the electric quantization unit (realized inside the quarks) and with the electron charge. In this framework the color charge can have a topological origin, with the number of colors being related to the order of the torsion subgroup. Finally, we discuss the possibility that the quantization of charge may be due to a weak non-exact component of the electromagnetic field extended over cosmological scales.

E. Minguzzi; C. Tejero Prieto; A. Lopez Almorox

2006-06-28

382

Topology of dynamical lattice configurations including results from dynamical overlap fermions  

E-print Network

We investigate how the topological charge density in lattice QCD simulations is affected by violations of chiral symmetry in different fermion actions. To this end we compare lattice configurations generated with a number of different actions including first configurations generated with exact overlap quarks. We visualize the topological profiles after mild smearing. In the topological charge correlator we measure the size of the positive core, which is known to vanish in the continuum limit. To leading order we find the core size to scale linearly with the lattice spacing with the same coefficient for all actions, even including quenched simulations. In the subleading term the different actions vary over a range of about 10 %. Our findings suggest that non-chiral lattice actions at current lattice spacings do not differ much for this specific observable related to topology, both among themselves and compared to overlap fermions.

Falk Bruckmann; Nigel Cundy; Florian Gruber; Thomas Lippert; Andreas Schäfer

2011-11-10

383

Measuring the Topological Susceptibility in a Fixed Sector: Results for Sigma Models  

E-print Network

For field theories with a topological charge Q, it is often of interest to measure the topological susceptibility chi_t = ( - ^2 ) / V. If we manage to perform a Monte Carlo simulation where Q changes frequently, chi_t can be evaluated directly. However, for local update algorithms and fine lattices, the auto-correlation time with respect to Q tends to be extremely long, which invalidates the direct approach. Nevertheless, the measurement of chi_t is still feasible, even when the entire Markov chain is topologically frozen. We test a method for this purpose, based on the correlation of the topological charge density, as suggested by Aoki, Fukaya, Hashimoto and Onogi. Our studies in non-linear sigma-models yield accurate results for chi_t, which confirm that the method is applicable. Unfortunately, for increasing volume the wanted signal gets rapidly suppressed, and this method requires huge statistics.

Irais Bautista; Wolfgang Bietenholz; Arthur Dromard; Urs Gerber; Christoph P. Hofmann; Héctor Mejía-Díaz; Marc Wagner

2015-03-23

384

Measuring the Topological Susceptibility in a Fixed Sector: Results for Sigma Models  

E-print Network

For field theories with a topological charge Q, it is often of interest to measure the topological susceptibility chi_t = ( - ^2 ) / V. If we manage to perform a Monte Carlo simulation where Q changes frequently, chi_t can be evaluated directly. However, for local update algorithms and fine lattices, the auto-correlation time with respect to Q tends to be extremely long, which invalidates the direct approach. Nevertheless, the measurement of chi_t is still feasible, even when the entire Markov chain is topologically frozen. We test a method for this purpose, based on the correlation of the topological charge density, as suggested by Aoki, Fukaya, Hashimoto and Onogi. Our studies in non-linear sigma-models yield accurate results for chi_t, which confirm that the method is applicable. Unfortunately, for increasing volume the wanted signal gets rapidly suppressed, and this method requires huge statistics.

Bautista, Irais; Dromard, Arthur; Gerber, Urs; Hofmann, Christoph P; Mejía-Díaz, Héctor; Wagner, Marc

2015-01-01

385

CHARGE syndrome  

PubMed Central

CHARGE syndrome was initially defined as a non-random association of anomalies (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, Ear anomalies/deafness). In 1998, an expert group defined the major (the classical 4C's: Choanal atresia, Coloboma, Characteristic ears and Cranial nerve anomalies) and minor criteria of CHARGE syndrome. Individuals with all four major characteristics or three major and three minor characteristics are highly likely to have CHARGE syndrome. However, there have been individuals genetically identified with CHARGE syndrome without the classical choanal atresia and coloboma. The reported incidence of CHARGE syndrome ranges from 0.1–1.2/10,000 and depends on professional recognition. Coloboma mainly affects the retina. Major and minor congenital heart defects (the commonest cyanotic heart defect is tetralogy of Fallot) occur in 75–80% of patients. Choanal atresia may be membranous or bony; bilateral or unilateral. Mental retardation is variable with intelligence quotients (IQ) ranging from normal to profound retardation. Under-development of the external genitalia is a common finding in males but it is less apparent in females. Ear abnormalities include a classical finding of unusually shaped ears and hearing loss (conductive and/or nerve deafness that ranges from mild to severe deafness). Multiple cranial nerve dysfunctions are common. A behavioral phenotype for CHARGE syndrome is emerging. Mutations in the CHD7 gene (member of the chromodomain helicase DNA protein family) are detected in over 75% of patients with CHARGE syndrome. Children with CHARGE syndrome require intensive medical management as well as numerous surgical interventions. They also need multidisciplinary follow up. Some of the hidden issues of CHARGE syndrome are often forgotten, one being the feeding adaptation of these children, which needs an early aggressive approach from a feeding team. As the child develops, challenging behaviors become more common and require adaptation of educational and therapeutic services, including behavioral and pharmacological interventions. PMID:16959034

Blake, Kim D; Prasad, Chitra

2006-01-01

386

Blobbed topological recursion: properties and applications  

E-print Network

We study the set of solutions $(\\omega_{g,n})_{g \\geq 0,n \\geq 1}$ of abstract loop equations. We prove that $\\omega_{g,n}$ is determined by its purely holomorphic part: this results in a decomposition that we call "blobbed topological recursion". This is a generalization of the theory of the topological recursion, in which the initial data $(\\omega_{0,1},\\omega_{0,2})$ is enriched by non-zero symmetric holomorphic forms in $n$ variables $(\\phi_{g,n})_{2g - 2 + n > 0}$. In particular, we establish for any solution of abstract loop equations: (1) a graphical representation of $\\omega_{g,n}$ in terms of $\\phi_{g,n}$; (2) a graphical representation of $\\omega_{g,n}$ in terms of intersection numbers on the moduli space of curves; (3) variational formulae under infinitesimal transformation of $\\phi_{g,n}$ ; (4) a definition for the free energies $\\omega_{g,0} = F_g$ respecting the variational formulae. We discuss in detail the application to the multi-trace matrix model and enumeration of stuffed maps.

Gaëtan Borot; Sergey Shadrin

2015-02-18

387

Charge transport  

NASA Astrophysics Data System (ADS)

We report results from theoretical studies of charge and energy dynamics in organic molecular and polymeric systems. The studies were performed by employing an extended three-dimensional version of the Su-Schrieffer-Heeger model. The equation of motion for the lattice as well as the time dependent Schrodinger equation were solved simultaneously. The dynamics of charge transport and charge separation in conjugated polymeric systems have been investigated as well as the time evolution following the injection of hot electrons and excitons. The results of such studies will contribute to the understanding and the development of organic electronic and photovoltaic devices as well as artificial photosynthesis.

Stafstrãm, Sven; Boman, Magnus; Hultell Andersson, Magnus

2004-03-01

388

Dirac Quantization and Fractional Magnetoelectric Effect on Interacting Topological Insulators  

E-print Network

We use Dirac quantization of flux to study fractional charges and axion angles \\theta in interacting topological insulators with gapless surface modes protected by time-reversal symmetry. In interacting topological insulators, there are two types of fractional axion angle due to conventional odd and nontrivial even flux quantization at the boundary. On even flux quantization in a gapped time reversal invariant system, we show that there is a halved quarter fractional quantum Hall effect on the surface with Hall conductance of p/4q e2/2h with p and q odd integers. The gapless surface modes can be characterized by a nontrivial Z2 anomaly emerged from the even flux quantization. It is suggested that the electron can be regarded as a bound state of fractionally charged quarks confined by a nonabelian color gauge field on the Dirac quantization of complex spinor fields.

Park, K -S

2010-01-01

389

Dirac Quantization and Fractional Magnetoelectric Effect on Interacting Topological Insulators  

E-print Network

We use Dirac quantization of flux to study fractional charges and axion angles \\theta in interacting topological insulators with gapless surface modes protected by time-reversal symmetry. In interacting topological insulators, there are two types of fractional axion angle due to conventional odd and nontrivial even flux quantization at the boundary. On even flux quantization in a gapped time reversal invariant system, we show that there is a halved quarter fractional quantum Hall effect on the surface with Hall conductance of p/4q e2/2h with p and q odd integers. The gapless surface modes can be characterized by a nontrivial Z2 anomaly emerged from the even flux quantization. It is suggested that the electron can be regarded as a bound state of fractionally charged quarks confined by a nonabelian color gauge field on the Dirac quantization of complex spinor fields.

K. -S. Park; H. Han

2010-10-10

390

Z2 anomaly and boundaries of topological insulators  

NASA Astrophysics Data System (ADS)

We study the edge and surface theories of topological insulators from the perspective of anomalies and identify a Z2 anomaly associated with charge conservation. The anomaly is manifested through a two-point correlation function involving creation and annihilation operators on two decoupled boundaries. Although charge conservation on each boundary requires this quantity to vanish, we find that it diverges. A corollary result is that under an insertion of a flux quantum, the ground state evolves to an exactly orthogonal state independent of the rate at which the flux is inserted. The anomaly persists in the presence of disorder and imposes sharp restrictions on possible low-energy theories. Being formulated in a many-body, field-theoretical language, the anomaly allows one to test the robustness of topological insulators to interactions in a concise way.

Ringel, Zohar; Stern, Ady

2013-09-01

391

OPTIMAL NETWORK TOPOLOGY DESIGN  

NASA Technical Reports Server (NTRS)

This program was developed as part of a research study on the topology design and performance analysis for the Space Station Information System (SSIS) network. It uses an efficient algorithm to generate candidate network designs (consisting of subsets of the set of all network components) in increasing order of their total costs, and checks each design to see if it forms an acceptable network. This technique gives the true cost-optimal network, and is particularly useful when the network has many constraints and not too many components. It is intended that this new design technique consider all important performance measures explicitly and take into account the constraints due to various technical feasibilities. In the current program, technical constraints are taken care of by the user properly forming the starting set of candidate components (e.g. nonfeasible links are not included). As subsets are generated, they are tested to see if they form an acceptable network by checking that all requirements are satisfied. Thus the first acceptable subset encountered gives the cost-optimal topology satisfying all given constraints. The user must sort the set of "feasible" link elements in increasing order of their costs. The program prompts the user for the following information for each link: 1) cost, 2) connectivity (number of stations connected by the link), and 3) the stations connected by that link. Unless instructed to stop, the program generates all possible acceptable networks in increasing order of their total costs. The program is written only to generate topologies that are simply connected. Tests on reliability, delay, and other performance measures are discussed in the documentation, but have not been incorporated into the program. This program is written in PASCAL for interactive execution and has been implemented on an IBM PC series computer operating under PC DOS. The disk contains source code only. This program was developed in 1985.

Yuen, J. H.

1994-01-01

392

On Space's Topology  

E-print Network

It seems to be a common belief that the space in which we live is a space-time manifold of dimension at least four. In the present article we wish to draw attention to a slightly different possibility - a space-time pseudomanifold (or even a generalized pseudomanifold of one dimension or another). Basically, a pseudomanifold is in a sense a manifold K with certain irremovable singularities inherited in the topological structure of K, and prior and independent to any metric or differential structure imposed on K. We explain this term for dimension 3, but it holds analogously for higher dimensions as well ([5], [2,Sec.4]).

Amos Altshuler

2010-04-11

393

Topological subsystem codes  

SciTech Connect

We introduce a family of two-dimensional (2D) topological subsystem quantum error-correcting codes. The gauge group is generated by two-local Pauli operators, so that two-local measurements are enough to recover the error syndrome. We study the computational power of code deformation in these codes and show that boundaries cannot be introduced in the usual way. In addition, we give a general mapping connecting suitable classical statistical mechanical models to optimal error correction in subsystem stabilizer codes that suffer from depolarizing noise.

Bombin, H. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139 (United States) and Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, Ontario N2L 2Y5 (Canada)

2010-03-15

394

Physics of three dimensional bosonic topological insulators: Surface Deconfined Criticality and Quantized Magnetoelectric Effect  

E-print Network

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. Recently, the mathematical classification of such states was discussed in terms of cohomology theory . However, 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. 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 chara...

Vishwanath, Ashvin

2012-01-01

395

Fractional Topological Insulators of Cooper Pairs Induced by the Proximity Effect  

NASA Astrophysics Data System (ADS)

Certain insulating materials with strong spin-orbit interaction can conduct currents along their edges or surfaces owing to the nontrivial topological properties of their electronic band structure. This phenomenon is somewhat similar to the integer quantum Hall effect of electrons in strong magnetic fields. Topological insulators analogous to the fractional quantum Hall effect are also possible, but have not yet been observed in any material. Here we show that a quantum well made from a topological band insulator such as Bi2Se3 or Bi2Te3, placed in contact with a superconductor, can be used to realize a two-dimensional topological state with macroscopic many-body quantum entanglement whose excitations carry fractional amounts of an electron’s charge and spin. This fractional topological insulator is a “pseudogap” state of induced spinful p-wave Cooper pairs, a new strongly correlated quantum phase with possible applications to spintronic devices and quantum computing.

Nikoli?, Predrag; Duric, Tanja; Tešanovi?, Zlatko

2013-04-01

396

Fractional topological insulators of Cooper pairs induced by the proximity effect.  

PubMed

Certain insulating materials with strong spin-orbit interaction can conduct currents along their edges or surfaces owing to the nontrivial topological properties of their electronic band structure. This phenomenon is somewhat similar to the integer quantum Hall effect of electrons in strong magnetic fields. Topological insulators analogous to the fractional quantum Hall effect are also possible, but have not yet been observed in any material. Here we show that a quantum well made from a topological band insulator such as Bi2Se3 or Bi2Te3, placed in contact with a superconductor, can be used to realize a two-dimensional topological state with macroscopic many-body quantum entanglement whose excitations carry fractional amounts of an electron's charge and spin. This fractional topological insulator is a "pseudogap" state of induced spinful p-wave Cooper pairs, a new strongly correlated quantum phase with possible applications to spintronic devices and quantum computing. PMID:23679757

Nikoli?, Predrag; Duric, Tanja; Tešanovi?, Zlatko

2013-04-26

397

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

Microsoft Academic Search

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

Wo-Jun Zhong; Yi-Shi Duan

2008-01-01

398

SHAPE AND TOPOLOGY OPTIMIZATION TECHNIQUES IN EIT  

E-print Network

Numerics Results Introduction in EIT 2 (Shape) Gradient method Topological expansion Detect objects Numerics Results Introduction in EIT 2 (Shape) Gradient method Topological expansion Detect objects Introduction in EIT 2 (Shape) Gradient method Topological expansion Concept of Electrical Impedance Tomography

Hintermüller, Michael

399

Part I. The Cosmological Vacuum from a Topological Perspective  

E-print Network

This article examines how the physical presence of field energy and particulate matter can be interpreted in terms of the topological properties of space-time. The theory is developed in terms of vector and matrix equations of exterior differential systems, which are not constrained by tensor diffeomorphic equivalences. The first postulate defines the field properties (a vector space continuum) of the Cosmological Vacuum in terms of matrices of basis functions that map exact differentials into neighborhoods of exterior differential 1-forms (potentials). The second postulate requires that the field equations must satisfy the First Law of Thermodynamics dynamically created in terms of the Lie differential with respect to a process direction field acting on the exterior differential forms that encode the thermodynamic system. The vector space of infinitesimals need not be global and its compliment is used to define particle properties as topological defects embedded in the field vector space. The potentials, as exterior differential 1-forms, are not (necessarily) uniquely integrable: the fibers can be twisted, leading to possible Chiral matrix arrays of certain 3-forms defined as Topological Torsion and Topological Spin. A significant result demonstrates how the coefficients of Affine Torsion are related to the concept of Field excitations (mass and charge); another demonstrates how thermodynamic evolution can describe the emergence of topological defects in the physical vacuum.

R. M. Kiehn

2007-12-07

400

A Comparative Study of Power Supply Architectures In Wireless Electric Vehicle Charging Systems  

NASA Astrophysics Data System (ADS)

Wireless inductive power transfer is a transformational and disruptive technology that enables the reliable and efficient transfer of electrical power over large air gaps for a host of unique applications. One such application that is now gaining much momentum worldwide is the wireless charging of electric vehicles (EVs). This thesis examines two of the primary power supply topologies being predominantly used for EV charging, namely the SLC and the LCL resonant full bridge inverter topologies. The study of both of these topologies is presented in the context of designing a 3 kW, primary side controlled, wireless EV charger with nominal operating parameters of 30 kHz centre frequency and range of coupling in the neighborhood of .18-.26. A comparison of both topologies is made in terms of their complexity, cost, efficiency, and power quality. The aim of the study is to determine which topology is better for wireless EV charging.

Esteban, Bryan

401

Topological quantization of current in quantum tunnel contacts  

Microsoft Academic Search

It is shown that an account of the Berry phase (a topological ?-term), together with a dissipative term in the effective action\\u000a S[?] of the tunnel contacts, induces a strong quantization of the tunnel current at low temperatures. This phenomenon, as the\\u000a Coulomb blockade, reflects a discrete charge structure of the quantum shot noise and can ensure a quantization of

S. A. Bulgadaev

2006-01-01

402

Topological phase shift in a cold-atom interferometer  

Microsoft Academic Search

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

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

1995-01-01

403

Charge Challenge  

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

404

Topological defects in two-dimensional crystals  

Microsoft Academic Search

By using topological current theory, we study the inner topological structure of the topological defects in two-dimensional (2D) crystal. We find that there are two elementary point defects topological current in two-dimensional crystal, one for dislocations and the other for disclinations. The topological quantization and evolution of topological defects in two-dimensional crystals are discussed. Finally, We compare our theory with

Yong Chenand; Wei-Kai Qi

2008-01-01

405

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

406

40 CFR 98.430 - Definition of the source category.  

Code of Federal Regulations, 2014 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...

2014-07-01

407

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

408

A natural topological insulator.  

PubMed

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

409

Axiomatic Digital Topology  

E-print Network

The paper presents a new set of axioms of digital topology, which are easily understandable for application developers. They define a class of locally finite (LF) topological spaces. An important property of LF spaces satisfying the axioms is that the neighborhood relation is antisymmetric and transitive. Therefore any connected and non-trivial LF space is isomorphic to an abstract cell complex. The paper demonstrates that in an n-dimensional digital space only those of the (a, b)-adjacencies commonly used in computer imagery have analogs among the LF spaces, in which a and b are different and one of the adjacencies is the â??maximalâ? one, corresponding to 3nï?­1 neighbors. Even these (a, b)-adjacencies have important limitations and drawbacks. The most important one is that they are applicable only to binary images. The way of easily using LF spaces in computer imagery on standard orthogonal grids containing only pixels or voxels and no cells of lower dimensions is suggested.

Kovalevsky, Vladimir

2010-01-01

410

Topology of viral evolution  

PubMed Central

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

411

Topology of viral evolution.  

PubMed

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

412

Propagators and topology  

NASA Astrophysics Data System (ADS)

Two popular perspectives on the non-perturbative domain of Yang-Mills theories are either in terms of the gluons themselves or in terms of collective gluonic excitations, i.e. topological excitations. If both views are correct, then they are only two different representations of the same underlying physics. One possibility to investigate this connection is by the determination of gluon correlation functions in topological background fields, as created by the smearing of lattice configurations. This is performed here for the minimal Landau gauge gluon propagator, ghost propagator, and running coupling, both in momentum and position space for SU(2) Yang-Mills theory. The results show that the salient low-momentum features of the propagators are qualitatively retained under smearing at sufficiently small momenta, in agreement with an equivalence of both perspectives. However, the mid-momentum behavior is significantly affected. These results are also relevant for the construction of truncations in functional methods, as they provide hints on necessary properties to be retained in truncations.

Maas, Axel

2015-03-01

413

Critical charge calculations for a bipolar SRAM array  

Microsoft Academic Search

The critical charge, Q{sub crit}, of a memory array storage cell is defined as the largest charge that can be injected without changing the cell`s logic state. The Q{sub crit} of a Schottky-coupled complementary bipolar SRAM array is evaluated in detail. An operational definition of critical charge is made, and the critical charge for the cell is determined by circuit

Leo B. Freeman

1996-01-01

414

On the Topological Properties of Quantized Spaces, I. The Notion of Dimension  

Microsoft Academic Search

An attempt is made to define meaningful counterparts of topological notions in quantized spaces. Finitely presented Abelian groups are used as a model for such spaces. Then the notion of dimension is introduced through a recursive definition and it is proven that for free Abelian groups it equals the number of generators.

John Mylopoulos; Theodosios Pavlidis

1971-01-01

415

Topological spectrum of classical configurations  

Microsoft Academic Search

For any classical field configuration or mechanical system with a finite number of degrees of freedom we introduce the concept of topological spectrum. It is based upon the assumption that for any classical configuration there exists a principle fiber bundle that contains all the physical and geometric information of the configuration. The topological spectrum follows from the investigation of the

Francisco Nettel; Hernando Quevedo

2007-01-01

416

Topological Fidelity in Sensor Networks  

Microsoft Academic Search

Sensor Networks are inherently complex networks, and many of their associated problems require analysis of some of their global characteristics. These are primarily affected by the topology of the network. We present in this paper, a general framework for a topological analysis of a network, and develop distributed algorithms in a generalized combinatorial setting in order to solve two seemingly

Harish Chintakunta; Hamid Krim

2011-01-01

417

Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator  

NASA Astrophysics Data System (ADS)

A three-dimensional (3D) topological insulator (TI) is a quantum state of matter with a gapped insulating bulk yet a conducting surface hosting topologically protected gapless surface states. One of the most distinct electronic transport signatures predicted for such topological surface states (TSS) is a well-defined half-integer quantum Hall effect (QHE) in a magnetic field, where the surface Hall conductivities become quantized in units of (1/2)e2/h (e being the electron charge, h the Planck constant) concomitant with vanishing resistance. Here, we observe a well-developed QHE arising from TSS in an intrinsic TI of BiSbTeSe2. Our samples exhibit surface-dominated conduction even close to room temperature, whereas the bulk conduction is negligible. At low temperatures and high magnetic fields perpendicular to the top and bottom surfaces, we observe well-developed integer quantized Hall plateaux, where the two parallel surfaces each contribute a half-integer e2/h quantized Hall conductance, accompanied by vanishing longitudinal resistance. When the bottom surface is gated to match the top surface in carrier density, only odd integer QH plateaux are observed, representing a half-integer QHE of two degenerate Dirac gases. This system provides an excellent platform to pursue a plethora of exotic physics and novel device applications predicted for TIs, ranging from magnetic monopoles and Majorana particles to dissipationless electronics and fault-tolerant quantum computers.

Xu, Yang; Miotkowski, Ireneusz; Liu, Chang; Tian, Jifa; Nam, Hyoungdo; Alidoust, Nasser; Hu, Jiuning; Shih, Chih-Kang; Hasan, M. Zahid; Chen, Yong P.

2014-12-01

418

Topologically induced local P and CP violation in hot QCD  

SciTech Connect

Very stringent experimental bounds exist on the amount of P and CP violation in strong interactions. Nevertheless, the presence of non-Abelian topological solutions and the axial anomaly make the issue of CP invariance in QCD non-trivial ('the strong CP problem'). Even in the absence of a global P and CP violation the fluctuations of topological charge in the QCD vacuum are expected to play an important role in the breaking of chiral symmetry, and in the mass spectrum and other properties of hadrons. Here I argue that topological fluctuations in hot QCD matter can become directly observable in the presence of a very intense external magnetic field by inducing local P- and CP-odd effects. These local parity-violating phenomena can be described by using the Maxwell-Chern-Simons, or axion, electrodynamics as an effective theory. Local P and CP violation in hot QCD matter can be observed in experiment through the 'chiral magnetic effect' - the separation of electric charge along the axis of magnetic field that is created by the colliding relativistic ions. There is a recent evidence for the electric charge separation relative to the reaction plane of heavy ion collisions from the STAR Collaboration at RHIC.

Kharzeev,D.E.

2009-02-01

419

Communication: An approximation to Bader's topological atom.  

PubMed

A new, more flexible definition of fuzzy Voronoi cells is proposed as a computationally efficient alternative to Bader's Quantum Theory of Atoms in Molecules (QTAIM) partitioning of the physical space for large-scale routine calculations. The new fuzzy scheme provides atomic charges, delocalization indices, and molecular energy components very close to those obtained using QTAIM. The method is flexible enough to either ignore the presence of spurious non-nuclear attractors or to readily incorporate them by introducing additional fuzzy Voronoi cells. PMID:23968064

Salvador, Pedro; Ramos-Cordoba, Eloy

2013-08-21

420

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

421

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

422

Implementing a Magnetic Charge Topology Model for Solar Active Regions  

E-print Network

Associates Division NorthWest Research Associates, Inc. 3380 Mitchell Lane, Boulder, CO 80301 graham of intersection between two separatrices (Baum & Bratenahl 1980; Greene 1988; Gorbachev & Somov 1988; Lau & Finn

Longcope, Dana

423

Solitons, charge fractionization, and the emergence of topological insulators  

E-print Network

Armchair Rings with semiconducting arms TB spectra N=15(ClassI)N=16(ClassII) Magnetic flux (magnetic field B) Magnetic field B #12;Dirac-Kronig-Penney Superlattice 1D Generalized Dirac equation a and b: any two of the three 2x2 Pauli matrices scalar (Higgs) field / position-dependent mass m

Yannouleas, Constantine

424

On the computational content of the Lawson topology  

E-print Network

On the computational content of the Lawson topology the Lawson topology is finer than the Scott topology, a stronger notion of computability is obtained. 1 Introduction The Lawson topology has its origins in topological algebra [8, 7]. A Lawson

Escardó, Martín

425

Majorana fermions in chiral topological ferromagnetic nanowires  

NASA Astrophysics Data System (ADS)

Motivated by a recent experiment in which zero-bias peaks have been observed in scanning tunneling microscopy (STM) experiments performed on chains of magnetic atoms on a superconductor, we show, by generalizing earlier work, that a multichannel ferromagnetic wire deposited on a spin-orbit coupled superconducting substrate can realize a nontrivial chiral topological superconducting state with Majorana bound states localized at the wire ends. The nontrivial topological state occurs for generic parameters requiring no fine tuning, at least for very large exchange spin splitting in the wire. We theoretically obtain the signatures which appear in the presence of an arbitrary number of Majorana modes in multiwire systems incorporating the role of finite temperature, finite potential barrier at the STM tip, and finite wire length. These signatures are presented in terms of spatial profiles of STM differential conductance, which clearly reveal zero-energy Majorana end modes and the prediction of a multiple Majorana based fractional Josephson effect. A substantial part of this work is devoted to a detailed critical comparison between our theory and the recent STM experiment claiming the observation of Majorana fermions in ferromagnetic atomic chains on a superconductor. The conclusion of this detailed comparison is that although the experimental observations are not manifestly inconsistent with our theoretical findings, the very small topological superconducting gap and the very high temperature of the experiment make it impossible to decisively verify the existence of a localized Majorana zero mode, as the spectral weight of the Majorana mode is necessarily spread over a very broad energy regime exceeding the size of the gap. Such an extremely broad (and extremely weak) conductance peak could easily arise from any subgap states existing in the rather complex system studied experimentally and may or may not have anything to do with a putative Majorana zero mode as discussed in the first half of our paper. Thus, although the experimental findings are indeed consistent with a highly broadened and weakened Majorana zero-bias peak, much lower experimental temperatures (and/or much larger experimental topological superconducting gaps) are necessary for any definitive conclusion.

Dumitrescu, Eugene; Roberts, Brenden; Tewari, Sumanta; Sau, Jay D.; Das Sarma, S.

2015-03-01

426

7 CFR 62.301 - Payment of fees and other charges.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 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...

2010-01-01

427

Assessment and control of electrostatic charges. [hazards to space missions  

NASA Technical Reports Server (NTRS)

The experience is described of NASA and DOD with electrostatic problems, generation mechanisms, and type of electrostatic hazards. Guidelines for judging possible effects of electrostatic charges on space missions are presented along with mathematical formulas and definitions.

Barrett, M.

1974-01-01

428

Dislocations in topological phases of matter and their topological terms  

NASA Astrophysics Data System (ADS)

When dislocations are present in topological insulators/superconductors and their variants, they are known to endow subgap boundstates. We revisit their physics from the viewpoint of topological field theories, discussing sevral issues among which are 1) the interplay of the Nieh-Yan torsional invariant with other topological terms, 2) possibile appearance of Nieh-Yan-like terms in nonlinear sigma models of competing orders, 3) the subtle controversy on the absence/existence of Callan-Harvey-like anomaly-inflow in the dual formulation.

Tanaka, Akihiro; Kikuchi, Toru

2013-03-01

429

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

430

Quantization and spacetime topology  

E-print Network

We consider classical and quantum dynamics of a free particle in de Sitter's space-times with different topologies to see what happens to space-time singularities of removable type in quantum theory. We find analytic solution of the classical dynamics. The quantum dynamics is solved by finding an essentially self-adjoint representation of the algebra of observables integrable to the unitary representations of the symmetry group of each considered gravitational system. The dynamics of a massless particle is obtained in the zero-mass limit of the massive case. Our results indicate that taking account of global properties of space-time enables quantization of particle dynamics in all considered cases.

Wlodzimierz Piechocki

2003-06-06

431

Topological code Autotune  

E-print Network

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.

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

2012-10-24

432

Topological Code Autotune  

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

433

The topology of fullerenes  

PubMed Central

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. PMID:25678935

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

2015-01-01

434

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

SciTech Connect

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

435

Spin-transfer torque generated by a topological insulator  

NASA Astrophysics Data System (ADS)

Magnetic devices are a leading contender for the implementation of memory and logic technologies that are non-volatile, that can scale to high density and high speed, and that do not wear out. However, widespread application of magnetic memory and logic devices will require the development of efficient mechanisms for reorienting their magnetization using the least possible current and power. There has been considerable recent progress in this effort; in particular, it has been discovered that spin-orbit interactions in heavy-metal/ferromagnet bilayers can produce strong current-driven torques on the magnetic layer, via the spin Hall effect in the heavy metal or the Rashba-Edelstein effect in the ferromagnet. In the search for materials to provide even more efficient spin-orbit-induced torques, some proposals have suggested topological insulators, which possess a surface state in which the effects of spin-orbit coupling are maximal in the sense that an electron's spin orientation is fixed relative to its propagation direction. Here we report experiments showing that charge current flowing in-plane in a thin film of the topological insulator bismuth selenide (Bi2Se3) at room temperature can indeed exert a strong spin-transfer torque on an adjacent ferromagnetic permalloy (Ni81Fe19) thin film, with a direction consistent with that expected from the topological surface state. We find that the strength of the torque per unit charge current density in Bi2Se3 is greater than for any source of spin-transfer torque measured so far, even for non-ideal topological insulator films in which the surface states coexist with bulk conduction. Our data suggest that topological insulators could enable very efficient electrical manipulation of magnetic materials at room temperature, for memory and logic applications.

Mellnik, A. R.; Lee, J. S.; Richardella, A.; Grab, J. L.; Mintun, P. J.; Fischer, M. H.; Vaezi, A.; Manchon, A.; Kim, E.-A.; Samarth, N.; Ralph, D. C.

2014-07-01

436

Spin-transfer torque generated by a topological insulator.  

PubMed

Magnetic devices are a leading contender for the implementation of memory and logic technologies that are non-volatile, that can scale to high density and high speed, and that do not wear out. However, widespread application of magnetic memory and logic devices will require the development of efficient mechanisms for reorienting their magnetization using the least possible current and power. There has been considerable recent progress in this effort; in particular, it has been discovered that spin-orbit interactions in heavy-metal/ferromagnet bilayers can produce strong current-driven torques on the magnetic layer, via the spin Hall effect in the heavy metal or the Rashba-Edelstein effect in the ferromagnet. In the search for materials to provide even more efficient spin-orbit-induced torques, some proposals have suggested topological insulators, which possess a surface state in which the effects of spin-orbit coupling are maximal in the sense that an electron's spin orientation is fixed relative to its propagation direction. Here we report experiments showing that charge current flowing in-plane in a thin film of the topological insulator bismuth selenide (Bi2Se3) at room temperature can indeed exert a strong spin-transfer torque on an adjacent ferromagnetic permalloy (Ni81Fe19) thin film, with a direction consistent with that expected from the topological surface state. We find that the strength of the torque per unit charge current density in Bi2Se3 is greater than for any source of spin-transfer torque measured so far, even for non-ideal topological insulator films in which the surface states coexist with bulk conduction. Our data suggest that topological insulators could enable very efficient electrical manipulation of magnetic materials at room temperature, for memory and logic applications. PMID:25056062

Mellnik, A R; Lee, J S; Richardella, A; Grab, J L; Mintun, P J; Fischer, M H; Vaezi, A; Manchon, A; Kim, E-A; Samarth, N; Ralph, D C

2014-07-24

437

A V2G vector control model of electric car charging and discharging machine  

Microsoft Academic Search

circuit topology structure of electric vehicle charging and discharging inverter based on space vector is presented. The control strategy uses rotation vector of the directional three-phase active tide reversible PWM converter, and the circuit topology is two-way control DC\\/DC converter with double buck reversible structure. In order to improve the efficiency of the charging and discharging machine, the main circuit

Xiaolei Wang; Pan Yan; Liang Yang; Wendao Yao; Guangwen Shi

2011-01-01

438

Local Charged States of the Gauge Field in Three-Dimensional Maxwell-Type Theories  

Microsoft Academic Search

Gauge-invariant local creation operators of charged states are introduced and studied in pure gauge theories of the Maxwell-type in (2+1) dimensions. These states are usually unphysical because of the subsidiary condition imposed on the physical subspace by Gauss' law. A dual Maxwell theory which possesses a topological electric charge is introduced. Pure electrodynamics lies in the sector where the topological

E. C. Marinq

1996-01-01

439

Loop Variables in Topological Gravity  

E-print Network

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

440

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

441

Topology of Chaotic Mixing Patterns  

E-print Network

A stirring device consisting of a periodic motion of rods induces a mapping of the fluid domain to itself, which can be regarded as a homeomorphism of a punctured surface. Having the rods undergo a topologically-complex motion guarantees at least a minimum amount of stretching of material lines, which is important for chaotic mixing. We use topological considerations to describe the nature of the injection of unmixed material into a central mixing region, which takes place at injection cusps. A topological index formula allow us to predict the possible types of unstable foliations that can arise for a fixed number of rods.

Jean-Luc Thiffeault; Matthew D. Finn; Emmanuelle Gouillart; Toby Hall

2008-08-26

442

Inexistence of Zeeman's fine topology  

E-print Network

The family of topologies that induce the Euclidean metric space on every time axis and every space axis exhibits no maximal element when partially ordered by the relation ``finer than'', as demonstrated in this article. One conclusion and two reflections emerge and are addressed herein: Conclusion: a. Zeeman's fine topology [1] and G\\"{o}bel's extension to arbitrary spacetimes [2] do not exist. Reflections: a. Both authors' attempts may be classified as type-2 strategies, within the taxonomy of [3]. b. How could these inexistent topologies be used for decades?

Norberto Sainz

2010-03-19

443

Does Zeeman's Fine Topology Exist?  

E-print Network

We work on the family of topologies for the Minkowski manifold M. We partially order this family by inclusion to form the lattice \\Sigma(M), and focus on the sublattice Z of topologies that induce the Euclidean metric space on every time axis and every space axis. We analyze the bounds of Z in the lattice \\Sigma(M), in search for its supremum. Our conclusion --that such a supremum does not belong in Z-- is compared with constructive proofs of existence of the fine topology, defined as the maximum of Z and conceived to play an essential role in contemporary physical theories. Essential mathematical and physical questions arise.

Norberto Sainz

2012-01-23

444

Visualizing vector field topology in fluid flows  

Microsoft Academic Search

Methods for automating the analysis and display of vector field topology in general, and flow topology in particular, are described. By using techniques to extract and visualize topological information, it is possible to combine the simplicity of schematic depictions with the quantitative accuracy of curves and surfaces computed directly from the data. Two-dimensional vector field topology is discussed, covering critical

James L. Helman; Lambertus Hesselink

1991-01-01

445

Evolving Neural Networks through Augmenting Topologies  

Microsoft Academic Search

An important question in neuroevolution is how to gain an advantage from evolving neural network topologies along with weights. We present a method, NeuroEvolution of Augmenting Topologies (NEAT), which outperforms the best fixed-topology method on a challenging benchmark reinforcement learning task. We claim that the increased efficiency is due to (1) employing a principled method of crossover of different topologies,

Kenneth O. Stanley; Risto Miikkulainen

2002-01-01

446

Finite topology as applied to image analysis  

Microsoft Academic Search

The notion of a cellular complex which is well known in the topology is applied to describe the structure of images. It is shown that the topology of cellular complexes is the only possible topology of finite sets. Under this topology no contradictions or paradoxes arise when defining connected subsets and their boundaries. Ways of encoding images as cellular complexes

V. A. Kovalevsky

1989-01-01

447

TOPOLOGY (MATE 3420) Semester 2011-10  

E-print Network

TOPOLOGY (MATE 3420) Semester 2011-10 Professor: Stefano Ferri Programme of the course. (A.) Point set topology. (1.) Topological spaces. (1.1) Basic concepts. (1.2) Neighbourhoods. (1.3) Bases and subbases. (2.) Topological spaces constructions. (2.1) Subspaces. (2.2) Continuous functions. (2

Ferri, Stefano

448

Geometric background charge: dislocations on capillary bridges  

E-print Network

Recent experiments have shown that colloidal crystals confined to weakly curved capillary bridges introduce groups of dislocations organized into `pleats' as means to relieve the stress caused by the Gaussian curvature of the surface. We consider the onset of this curvature-screening mechanism, by examining the energetics of isolated dislocations and interstitials on capillary bridges with free boundaries. The boundary provides an essential contribution to the problem, akin to a background charge that "neutralizes" the unbalanced integrated curvature of the surface. This makes it favorable for topologically neutral dislocations and groups of dislocations - rather than topologically charged disclinations and scars - to relieve the stress caused by the unbalanced gaussian curvature of the surface. This effect applies to any crystal on a surface with non-vanishing integrated Gaussian curvature and stress-free boundary conditions. We corroborate the analytic results by numerically computing the energetics of a defected lattice of springs confined to surfaces with weak positive and negative curvature

William Irvine; Vincenzo Vitelli

2012-06-19

449

Definitions of dwelling  

E-print Network

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

450

Holding Charge  

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).

Eric Muller

1995-01-01

451

Algebraic & Geometric Topology 9 (2009) 22472309 2247 Tangle analysis of difference topology experiments  

E-print Network

Algebraic & Geometric Topology 9 (2009) 2247­2309 2247 Tangle analysis of difference topology topological methods for analyzing difference topology experiments involving 3­string tangles. Difference topology is a novel technique used to unveil the structure of stable protein-DNA complexes. We analyze

Vazquez, Mariel

2009-01-01

452

A definition of dyslexia  

Microsoft Academic Search

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

453

Characterization of heterocyclic rings through quantum chemical topology.  

PubMed

Five-membered rings are found in a myriad of molecules important in a wide range of areas such as catalysis, nutrition, and drug and agrochemical design. Systematic insight into their largely unexplored chemical space benefits from first principle calculations presented here. This study comprehensively investigates a grand total of 764 different rings, all geometry optimized at the B3LYP/6-311+G(2d,p) level, from the perspective of Quantum Chemical Topology (QCT). For the first time, a 3D space of local topological properties was introduced, in order to characterize rings compactly. This space is called RCP space, after the so-called ring critical point. This space is analogous to BCP space, named after the bond critical point, which compactly and successfully characterizes a chemical bond. The relative positions of the rings in RCP space are determined by the nature of the ring scaffold, such as the heteroatoms within the ring or the number of ?-bonds. The summed atomic QCT charges of the five ring atoms revealed five features (number and type of heteroatom, number of ?-bonds, substituent and substitution site) that dictate a ring's net charge. Each feature independently contributes toward a ring's net charge. Each substituent has its own distinct and systematic effect on the ring's net charge, irrespective of the ring scaffold. Therefore, this work proves the possibility of designing a ring with specific properties by fine-tuning it through manipulation of these five features. PMID:23795608

Griffiths, Mark Z; Popelier, Paul L A

2013-07-22

454

Child Abuse: Definition.  

ERIC Educational Resources Information Center

The purpose of this paper was to elaborate on the definitions of child abuse in order to improve the understanding of child abuse. The definitions given by the U.S. House Joint Committee on Child Abuse in the Child Abuse Prevention and Treatment Act, and in research by Holden (1984), are cited. These definitions refer to the nature of abusive acts…

Wilson, Timothy L.-Y.

455

Correlation effects on topological insulator  

E-print Network

The strong correlation effects on topological insulator are studied in a two-sublattice system with an onsite single-particle energy difference $\\Delta$ between two sublattices. At $\\Delta=0$, increasing the onsite interaction strength $U$ drives the transition from the quantum spin Hall insulating state to the non-topological antiferromagnetic Mott-insulating (AFMI) state. When $\\Delta$ is larger than a certain value, a topologically trivial band insulator or AFMI at small values of $U$ may change into a quantum anomalous Hall state with antiferromagnetic ordering at intermediate values of $U$. Further increasing $U$ drives the system back into the topologically trivial state of AFMI. The corresponding phenomena is observable in the solid state and cold atom systems. We also propose a scheme to realize and detect these effects in cold atom systems.

Xiong-Jun Liu; Yang Liu; Xin Liu

2010-11-24

456

Phonon-induced topological insulation  

NASA Astrophysics Data System (ADS)

We develop an approximate theory of phonon-induced topological insulation in Dirac materials. In the weak-coupling regime, long-wavelength phonons may favor topological phases in Dirac insulators with direct and narrow band gaps. This phenomenon originates from electron-phonon matrix elements, which change qualitatively under a band inversion. A similar mechanism applies to weak Coulomb interactions and spin-independent disorder; however, the influence of these on band topology is largely independent of temperature. As applications of the theory, we evaluate the temperature dependence of the critical thickness and the critical stoichiometric ratio for the topological transition in CdTe/HgTe quantum wells and in BiTl(S1-?Se?)2, respectively.

Saha, Kush; Garate, Ion

2014-05-01

457

Topics in topological band systems  

NASA Astrophysics Data System (ADS)

The discovery of integer quantum Hall effect and its subsequent theoretical formulation heralded a new paradigm of thinking in condensed matter physics, which has by now blossomed into the rapidly growing field of topological phases. In this work we investigate several mutually related topics in the framework of topological band theory. In Chapter 2, we study solutions to boundary states on a lattice and see how they are related to the bulk topology. To elicit a real space manifestation of the non-trivial topology, the presence of a physical edge is not strictly necessary. We study two other possibilities, namely the entanglement spectrum associated with an imaginary spatial boundary, and the localization centers of Wannier functions, in Chapters 3,4, and 5. Topological classification through discrete indices is so far possible only for systems described by pure quantum states---in the existing scheme, quantization is lost for systems in mixed states. In Chapter 6, we present a program through which discrete topological indices can be defined for topological band systems at finite temperature, based on Uhlmann's parallel transport of density matrices. The potential of topologocal insulators in realistic applications lies in the existence of Dirac nodes on its surface spectrum. Dirac physics, however, is not exclusive to TI surfaces. In a recently discovered class of materials known as Weyl semimetals, energy nodes which emit linear dispersions also occur in the bulk material. In Chapter 7, we study the possibility of resonance states induced by localized impurities near the nodal energy in Weyl semimetals, which will help us in understanding the stability of density-of-state suppression at the energy nodes. Finally, in Chapter 8, we apply the topological characterization developed for noninteracting particles to a class of interacting spin models in 3D, which are generalizations of Kitaev's honeycomb model, and identify several exotic quantum phases such as spin metals and spin semimetals.

Huang, Zhoushen

458

The Magnetoconductance in Topological Insulators  

NASA Astrophysics Data System (ADS)

Surface conduction in topological insulators is protected against both disorder and interactions, and obeys a linear Dirac dispersion. Experimentally it remains difficult to disentangle the bulk and surface contributions to the conductance, because impurities mix states and produce impurity bands, and doping shifts the Fermi level. Measurements of the magnetoconductance are a very popular way of verifying in individual samples that surface states are contributing to the conductance. We present results which will be useful for diagnostic evaluations of topological insulator sample quality.

Sacksteder, Vincent; Dai, Xi

2013-03-01

459

Refining the shifted topological vertex  

SciTech Connect

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

460

Renormalizability of Topologically Massive Gravity  

E-print Network

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

2009-08-14

461

Experimental Realizations of Magnetic Topological Insulator and Topological Crystalline Insulator  

NASA Astrophysics Data System (ADS)

Over the past few years the experimental research on three-dimensional topological insulators have emerged as one of the most rapidly developing fields in condensed matter physics. In this talk, we report on two new developments in the field: The first part is on the dynamic interplay between ferromagnetism and the Z2 topological insulator state (leading to a magnetic topological insulator). We present our spin-resolved photoemission and magnetic dichroic experiments on MBE grown films where a hedgehog-like spin texture is revealed on the magnetically ordered surface of Mn-Bi2Se3 revealing a Berry's phase gradient in energy-momentum space of the crystal. A chemically/electrically tunable Berry's phase switch is further demonstrated via the tuning of the spin groundstate in Mn-Bi2Se3 revealed in our data (Nature Physics 8, 616 (2012)). The second part of this talk describes our experimental observation of a new topological phase of matter, namely a topological crystalline insulator where space group symmetries replace the role of time-reversal symmetry in an otherwise Z2 topological insulator predicted in theory. We experimentally investigate the possibility of a mirror symmetry protected topological phase transition in the Pb1-xSnxTe alloy system, which has long been known to contain an even number of band inversions based on band theory. Our experimental results show that at a composition below the theoretically predicted band inversion, the system is fully gapped, whereas in the band-inverted regime, the surface exhibits even number of spin-polarized Dirac cone states revealing mirror-protected topological order (Nature Communications 3, 1192 (2012)) distinct from that observed in Z2 topological insulators. We discuss future experimental possibilities opened up by these new developments in topological insulators research. This work is in collaboration with M. Neupane, C. Liu, N. Alidoust, I. Belopolski, D. Qian, D.M. Zhang, A. Richardella, A. Marcinkova, Q. Gibson, R. Sankar, Y.J. Wang, T. Chang, H. Jeng, H. Lin, L.A. Wray, J.D. Denlinger, M. Leandersson, T. Balasubramanian, J. Sánchez-Barriga, O. Rader, G. Landolt, B. Slomski, J.H. Dil, F.C. Chou, E. Morosan, N. Samarth, R.J. Cava and M.Z. Hasan.

Xu, Suyang

2013-03-01

462

Strong correlations and topological order in one-dimensional systems  

NASA Astrophysics Data System (ADS)

This thesis presents theoretical studies of strongly correlated systems as well as topologically ordered systems in 1D. Non-Fermi liquid behavior characteristic of interacting 1D electron systems is investigated with an emphasis on experimentally relevant setups and observables. The existence of end Majorana fermions in a 1D p-wave superconductor subject to periodic, incommensurate and disordered potentials is studied. The Tomonaga-Luttinger liquid (TLL), a model of interacting electrons in one spatial dimension, is considered in the context of two systems of experimental interest. First, a study of the electronic properties of single-walled armchair carbon nanotubes in the presence of transverse electric and magnetic fields is presented. As a result of their effect on the band structure and electron wave functions, fields alter the nature of the (effective) Coulomb interaction in tubes. In particular, it is found that fields couple to nanotube bands (or valleys), a quantum degree of freedom inherited from the underlying graphene lattice. As revealed by a detailed TLL calculation, it is predicted that fields induce electrons to disperse into their spin, band, and charge components. Fields also provide a means of tuning the shell-filling behavior associated with short tubes. The phenomenon of charge fractionalization is investigated in a one-dimensional ring. TLL theory predicts that momentum-resolved electrons injected into the ring will fractionalize into clockwise- and counterclockwise-moving quasiparticles. As a complement to transport measurements in quantum wires connected to leads, non-invasive measures involving the magnetic field profiles around the ring are proposed. Topological aspects of 1D p-wave superconductors are explored. The intimate connection between non-trivial topology (fermions) and spontaneous symmetry breaking (spins) in one-dimension is investigated. Building on this connection, a spin ladder system endowed with vortex degrees of freedom is proposed in order to study the effects that inhomogeneous potentials have on the topological phase diagram. Periodic vortex patterns yield a rich parameter space for tuning into a topologically non-trivial phase. This analysis hinges on the development of a topological invariant based on the wave function of Majorana fermions which inhabit the ends of the system and are robust to disorder. The method is generalized to aperiodic and disordered potentials. The topological phase diagram of such systems is studied; numerical and analytic results are found to be in close agreement.

De Gottardi, Wade Wells

463

An Acoustic Charge Transport Imager for High Definition Television Applications: Reliability Modeling and Parametric Yield Prediction of GaAs Multiple Quantum Well Avalanche Photodiodes. Degree awarded Oct. 1997  

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

464

Lattice QCD with fixed topology  

E-print Network

The overlap Dirac operator, which satisfies the Ginsparg-Wilson relation, realizes exact chiral symmetry on the lattice without any unphysical doubler modes. To perform the path integrals, one should, however, note that the overlap fermion determinant has discontinuities where the topology is ill-defined, its locality is doubtful, and the numerical cost is suddenly enhanced. An interesting solution would be to concentrate on a fixed topological sector in the full configuration space. In this thesis, we test a gauge action which automatically satisfies Luescher's admissibility condition, as well as an additional (large) negative mass Wilson fermion action in the quenched study (with no light quark). Both of them would keep the topology along the HMC simulations. The quark potential and the topology stability are investigated with different lattice sizes and different couplings. The results of quenched QCD in the $\\epsilon$-regime are also presented as an example of the lattice studies with fixed topology. Remarkable quark mass and topology dependences of meson correlators allow us to determine the fundamental parameters of the effective theory, in which the exact chiral symmetry with the Ginsparg Wilson relation plays a crucial role.

Hidenori Fukaya

2006-06-26

465

TRW CHARGED DROPLET SCRUBBER CORROSION STUDIES  

EPA Science Inventory

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...

466

Landau theory of topological defects in multiferroic hexagonal manganites  

NASA Astrophysics Data System (ADS)

Topological defects in ordered states with spontaneously broken symmetry often have unusual physical properties, such as fractional electric charge or a quantized magnetic field flux, originating from their non-trivial topology. Coupled topological defects in systems with several coexisting orders give rise to unconventional functionalities, such as the electric-field control of magnetization in multiferroics resulting from the coupling between the ferroelectric and ferromagnetic domain walls. Hexagonal manganites provide an extra degree of freedom: in these materials, both ferroelectricity and magnetism are coupled to an additional, non-ferroelectric structural order parameter. Here we present a theoretical study of topological defects in hexagonal manganites based on Landau theory with parameters determined from first-principles calculations. We explain the observed flip of electric polarization at the boundaries of structural domains, the origin of the observed discrete vortices, and the clamping between ferroelectric and antiferromagnetic domain walls. We show that structural vortices induce magnetic ones and that, consistent with a recent experimental report, ferroelectric domain walls can carry a magnetic moment.

Artyukhin, Sergey; Delaney, Kris T.; Spaldin, Nicola A.; Mostovoy, Maxim

2014-01-01

467

Topological strings and 5d T_N partition functions  

E-print Network

We evaluate the Nekrasov partition function of 5d gauge theories engineered by webs of 5-branes, using the refined topological vertex on the dual Calabi-Yau threefolds. The theories include certain non-Lagrangian theories such as the T_N theory. The refined topological vertex computation generically contains contributions from decoupled M2-branes which are not charged under the 5d gauge symmetry engineered. We argue that, after eliminating them, the refined topological string partition function agrees with the 5d Nekrasov partition function. We explicitly check this for the T_3 theory as well as Sp(1) gauge theories with N_f = 2, 3, 4 flavors. In particular, our method leads to a new expression of the Sp(1) Nekrasov partition functions without any contour integrals. We also develop prescriptions to calculate the partition functions of theories obtained by Higgsing the T_N theory. We compute the partition function of the E_7 theory via this prescription, and find the E_7 global symmetry enhancement. We finally discuss a potential application of the refined topological vertex to non-toric web diagrams.

Hirotaka Hayashi; Hee-Cheol Kim; Takahiro Nishinaka

2014-05-06

468

Landau theory of topological defects in multiferroic hexagonal manganites.  

PubMed

Topological defects in ordered states with spontaneously broken symmetry often have unusual physical properties, such as fractional electric charge or a quantized magnetic field flux, originating from their non-trivial topology. Coupled topological defects in systems with several coexisting orders give rise to unconventional functionalities, such as the electric-field control of magnetization in multiferroics resulting from the coupling between the ferroelectric and ferromagnetic domain walls. Hexagonal manganites provide an extra degree of freedom: in these materials, both ferroelectricity and magnetism are coupled to an additional, non-ferroelectric structural order parameter. Here we present a theoretical study of topological defects in hexagonal manganites based on Landau theory with parameters determined from first-principles calculations. We explain the observed flip of electric polarization at the boundaries of structural domains, the origin of the observed discrete vortices, and the clamping between ferroelectric and antiferromagnetic domain walls. We show that structural vortices induce magnetic ones and that, consistent with a recent experimental report, ferroelectric domain walls can carry a magnetic moment. PMID:24162883

Artyukhin, Sergey; Delaney, Kris T; Spaldin, Nicola A; Mostovoy, Maxim

2014-01-01

469

Topological approximation of the nonlinear Anderson model  

NASA Astrophysics Data System (ADS)

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.

Milovanov, Alexander V.; Iomin, Alexander

2014-06-01

470

Mean Field Theory of Josephson Junction Arrays with Charge Frustration  

E-print Network

Using the path integral approach, we provide an explicit derivation of the equation for the phase boundary for quantum Josephson junction arrays with offset charges and non-diagonal capacitance matrix. For the model with nearest neighbor capacitance matrix and uniform offset charge $q/2e=1/2$, we determine, in the low critical temperature expansion, the most relevant contributions to the equation for the phase boundary. We explicitly construct the charge distributions on the lattice corresponding to the lowest energies. We find a reentrant behavior even with a short ranged interaction. A merit of the path integral approach is that it allows to provide an elegant derivation of the Ginzburg-Landau free energy for a general model with charge frustration and non-diagonal capacitance matrix. The partition function factorizes as a product of a topological term, depending only on a set of integers, and a non-topological one, which is explicitly evaluated.

G. Grignani; A. Mattoni; P. Sodano; A. Trombettoni

1999-02-12

471

Borohydrides: from sheet to framework topologies.  

PubMed

The five novel compounds ALiM(BH4)4 (A = K or Rb; M = Mg or Mn) and K3Li2Mg2(BH4)9 crystallizing in the space groups Aba2 and P2/c, respectively, represent the first two-dimensional topologies amongst homoleptic borohydrides. The crystal structures have been solved, refined and characterized by synchrotron X-ray powder diffraction, neutron powder diffraction and solid-state DFT calculations. Minimal energies of ordered models corroborate crystal symmetries retrieved from diffraction data. The layered Li-Mg substructure forms negatively charged uninodal 4-connected networks. It is shown that this connectivity cannot generate the long sought-after, bimetallic Li-Mg borohydrides without countercations when assuming preferred coordination polyhedra as found in Mg(BH4)2 and LiBH4. The general properties of the trimetallic compound series are analogous with the anhydrous aluminosilicates. Additionally, a relationship with zeolites is suggested, which are built from three-dimensional Al-Si-O networks with a negative charge on them. The ternary metal borohydride systems are of interest due to their potential as novel hydridic frameworks and will allow exploration of the structural chemistry of light-metal systems otherwise subject to eutectic melting. PMID:24699844

Schouwink, P; Ley, M B; Jensen, T R; Smr?ok, L'; ?erný, R

2014-06-01

472

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

473

Topology optimization under stochastic stiffness  

NASA Astrophysics Data System (ADS)

Topology optimization is a systematic computational tool for optimizing the layout of materials within a domain for engineering design problems. It allows variation of structural boundaries and connectivities. This freedom in the design space often enables discovery of new, high performance designs. However, solutions obtained by performing the optimization in a deterministic setting may be impractical or suboptimal when considering real-world engineering conditions with inherent variabilities including (for example) variabilities in fabrication processes and operating conditions. The aim of this work is to provide a computational methodology for topology optimization in the presence of uncertainties associated with structural stiffness, such as uncertain material properties and/or structural geometry. Existing methods for topology optimization under deterministic conditions are first reviewed. Modifications are then proposed to improve the numerical performance of the so-called Heaviside Projection Method (HPM) in continuum domains. Next, two approaches, perturbation and Polynomial Chaos Expansion (PCE), are proposed to account for uncertainties in the optimization procedure. These approaches are intrusive, allowing tight and efficient coupling of the uncertainty quantification with the optimization sensitivity analysis. The work herein develops a robust topology optimization framework aimed at reducing the sensitivity of optimized solutions to uncertainties. The perturbation-based approach combines deterministic topology optimization with a perturbation method for the quantification of uncertainties. The use of perturbation transforms the problem of topology optimization under uncertainty to an augmented deterministic topology optimization problem. The PCE approach combines the spectral stochastic approach for the representation and propagation of uncertainties with an existing deterministic topology optimization technique. The resulting compact representations for the response quantities allow for efficient and accurate calculation of sensitivities of response statistics with respect to the design variables. The proposed methods are shown to be successful at generating robust optimal topologies. Examples from topology optimization in continuum and discrete domains (truss structures) under uncertainty are presented. It is also shown that proposed methods lead to significant computational savings when compared to Monte Carlo-based optimization which involve multiple formations and inversions of the global stiffness matrix and that results obtained from the proposed method are in excellent agreement with those obtained from a Monte Carlo-based optimization algorithm.

Asadpoure, Alireza

474

HYBRID DC ACCURATE CHARGE AMPLIFIER FOR LINEAR PIEZOELECTRIC POSITIONING  

Microsoft Academic Search

Abstract: Piezoelectric transducers are known,to exhibit l ess hysterisis when,driven with current or charge rather than voltage. Despite this advanta ge, such methods have found little practical application due to the poor low frequency response of present current and charge driver designs. This paper introduces a new circuit topology free from low-frequency drift and DC load offsets. The hybrid load

Andrew J. Fleming; S. O. Reza Moheimani

475

Phase transition of electrically charged Ricci-flat black holes  

Microsoft Academic Search

We study phase transition between electrically charged Ricci-flat black holes and AdS soliton spacetime of Horowitz and Myers in five dimensions. Boundary topology for both of them is $S^1 \\\\times S^1 \\\\times R^2$. We consider Reissner-Nordstrom black hole and R-charged black holes and find that phase transition of these black holes to AdS soliton spacetime depends on the relative size

Nabamita Banerjee; Suvankar Dutta

2007-01-01

476

Spin Charge Separation in the Quantum Spin Hall State  

SciTech Connect

The quantum spin Hall state is a topologically non-trivial insulator state protected by the time reversal symmetry. We show that such a state always leads to spin-charge separation in the presence of a {pi} flux. Our result is generally valid for any interacting system. We present a proposal to experimentally observe the phenomenon of spin-charge separation in the recently discovered quantum spin Hall system.

Qi, Xiao-Liang; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-03-19

477

A magnetic monopole in topological insulator: exact solution  

E-print Network

The Witten effect tells that a unit magnetic monopole can bind a half elementary charge in an axion media. We present an exact solution of a magnetic monopole in a topological insulator that was proposed to be an axion media recently. It is found that a magnetic monopole can induce one zero energy state bound to it and one surface state of zero energy. The two states are quite robust, but the degeneracy can be removed by external fields. For a finite size system, the interference of two states may lift the degeneracy, and the resulting states have one half near the origin and another half around the surface, which realizes the Witten effect. However, the energy difference decays exponentially with the size of the system. The exact solution does not fully support the realization of the Witten effect in a topological insulator.

Yuan-Yuan Zhao; Shun-Qing Shen

2012-11-15

478

Exotic quantum phase transitions of strongly interacting topological insulators  

NASA Astrophysics Data System (ADS)

Using determinant quantum Monte Carlo simulations, we demonstrate that an extended Hubbard model on a bilayer honeycomb lattice has two novel quantum phase transitions. The first is a quantum phase transition between the weakly interacting gapless Dirac fermion phase and a strongly interacting fully gapped and symmetric trivial phase, which cannot be described by the standard Gross-Neveu model. The second is a quantum critical point between a quantum spin Hall insulator with spin Sz conservation and the previously mentioned strongly interacting fully gapped phase. At the latter quantum critical point the single-particle excitations remain gapped, while spin and charge gaps both close. We argue that the first quantum phase transition is related to the Z16 classification of the topological superconductor 3He-B phase with interactions, while the second quantum phase transition is a topological phase transition described by a bosonic O (4 ) nonlinear sigma model field theory with a ? term.

Slagle, Kevin; You, Yi-Zhuang; Xu, Cenke

2015-03-01

479

Generalized Ablowitz-Ladik hierarchy in topological string theory  

E-print Network

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

2014-03-23

480

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

481

Topological quantization of vacuum angle with magnetic monopoles and the solution to the strong CP problem  

Microsoft Academic Search

The author discusses and reviews briefly about the recently proposed solution to the strong CP problem by the author. It is shown that the vacuum angle in non-abelian gauge theories with magnetic monopoles in the theoies must be quantized. Consequently, the strong CP problem can be solved due to the existence of magnetic monopoles of topological charges n=1, -1, or

Zhang

1993-01-01

482

Scanning Tunnelling Spectroscopic Studies of Dirac Fermions in Graphene and Topological Insulators  

E-print Network

state (SS) of a strong topological insulator (STI), Bi2Se3. For mono-layer graphene grown on Cu by chemical vapour deposition (CVD), strain-induced scalar and gauge potentials are manifested by the charging quintuple layers (QL). These findings are characteristic of the SS of a STI and are direct manifestation

Yeh, Nai-Chang

483

Topology dependent electronic and dielectric properties of free standing alloyed ultrathin nanowires of noble metals  

NASA Astrophysics Data System (ADS)

Structural, electronic and dielectric properties of free standing ultrathin alloyed nanowires of noble metals (AgAu, AgCu, AgPt, AuCu, AuPt and CuPt) in various topologies (linear, ladder and double zigzag) have been studied by using ab initio density functional theory. Among the different topologies of alloyed ultrathin nanowires of noble metals, double zigzag (DZZ) topology has been found to be most stable and the linear topology the least stable. Also the binding energy of alloyed nanowires of AgAu and AuCu for all the studied topologies is found to be larger than the average binding energy of the corresponding pristine nanowires, indicating a strong alloying effect for these topologies. Among electronic properties, the alloyed nanowires of different topologies containing Pt (AgPt, AuPt and AuCu) are found to be ferromagnetic in nature, a result of d charge depletion in Ag, Au and Cu sites and d charge gain at Pt sites. On the other hand, all the topologies (except ladder topology) of alloyed nanowires viz. AgAu, AgCu and AuCu are found to be semiconducting in nature. The optical properties of the studied alloyed nanowires have been found to be different from their corresponding pristine nanowires due to change in the band structure on alloying. The linear topology of AgAu, AgCu and AuCu and DZZ topologies (DZZ1, DZZ2 and DZZ3) of Ag, Au, Cu, AgAu, AgCu and AuCu are semiconducting in nature with band gap lying in the infrared region, causing absorption of photons from a visible spectrum leading to blackish appearance. Whereas, remaining topologies are found to be metallic in nature, with plasmon frequency lying in the energy range of 0.35 eV to 1.62 eV, which is in the infrared region and hence these nanowires shall appear to be transparent to the visible region.

Kumar, Arun; Kumar, Ashok; Ahluwalia, P. K.

2014-08-01

484

Robust transport signatures of topological superconductivity in topological insulator nanowires.  

PubMed

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

485

Topological Invariants in Point Group Symmetric Photonic Topological Insulators  

E-print Network

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