Search query: insulator detect classification

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abstract: Topological insulators are new states of quantum matter which cannot be adiabatically connected to conventional insulators and semiconductors. They are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time reversal symmetry. These topological materials have been theoretically predicted and experimentally observed in a variety of systems, including HgTe quantum wells, BiSb alloys, and Bi2Te3 and Bi2Se3 crystals. Theoretical models, materials properties, and experimental results on two dimensional and three dimensional topological insulators are reviewed, and both the topological band theory and the topological field theory are discussed. Topological superconductors have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions. The theory of topological superconductors is reviewed, in close analogy to the theory of topological insulators.
author_names: Xiao-liang Qi

Shou-Cheng Zhang
title: Topological insulators and superconductors
year: 2011

abstract: Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have protected conducting states on their edge or surface. These states are possible due to the combination of spin orbit interactions and time reversal symmetry. The two dimensional (2D) topological insulator is a quantum spin Hall insulator, which is a close cousin of the integer quantum Hall state. A three dimensional (3D) topological insulator supports novel spin polarized 2D Dirac fermions on its surface. In this Colloquium the theoretical foundation for topological insulators and superconductors is reviewed and recent experiments are described in which the signatures of topological insulators have been observed. Transport experiments on \mathrm{Hg}\mathrm{Te}\mathrm{Cd}\mathrm{Te} quantum wells are described that demonstrate the existence of the edge states predicted for the quantum spin Hall insulator. Experiments on \mathrm{Bi}}_{1\ensuremath{ }x}\mathrm{Sb}}_{x} \mathrm{Bi}}_{2}\mathrm{Se}}_{3} \mathrm{Bi}}_{2}\mathrm{Te}}_{3} and \mathrm{Sb}}_{2}\mathrm{Te}}_{3} are then discussed that establish these materials as 3D topological insulators and directly probe the topology of their surface states. Exotic states are described that can occur at the surface of a 3D topological insulator due to an induced energy gap. A magnetic gap leads to a novel quantum Hall state that gives rise to a topological magnetoelectric effect. A superconducting energy gap leads to a state that supports Majorana fermions and may provide a new venue for realizing proposals for topological quantum computation. Prospects for observing these exotic states are also discussed, as well as other potential device applications of topological insulators.
author_names: M Zahid Hasan

C L Kane
title: Colloquium Topological insulators
year: 2010

abstract: Topological insulators represent a new quantum state of matter which is characterized by peculiar edge or surface states that show up due to a topological character of the bulk wave functions. This review presents a pedagogical account on topological insulator materials with an emphasis on basic theory and materials properties. After presenting a historical perspective and basic theories of topological insulators, it discusses all the topological insulator materials discovered as of May 2013, with some illustrative descriptions of the developments in materials discoveries in which the author was involved. A summary is given for possible ways to confirm the topological nature in a candidate material. Various synthesis techniques as well as the defect chemistry that are important for realizing bulk insulating samples are discussed. Characteristic properties of topological insulators are discussed with an emphasis on transport properties. In particular, the Dirac fermion physics and the resulting peculiar qu.
author_names: Yoichi Ando
title: Topological Insulator Materials
year: 2013

abstract: Certain insulators have exotic metallic states on their surfaces. These states are formed by topological effects that also render the electrons travelling on such surfaces insensitive to scattering by impurities. Such topological insulators may provide new routes to generating novel phases and particles, possibly finding uses in technological applications in spintronics and quantum computing.
author_names: Joel E Moore
title: The birth of topological insulators
venue: Nature
year: 2010

abstract: This graduate level textbook is the first pedagogical synthesis of the field of topological insulators and superconductors, one of the most exciting areas of research in condensed matter physics. Presenting the latest developments, while providing all the calculations necessary for a self contained and complete description of the discipline, it is ideal for graduate students and researchers preparing to work in this area, and it will be an essential reference both within and outside the classroom. The book begins with simple concepts such as Berry phases, Dirac fermions, Hall conductance and its link to topology, and the Hofstadter problem of lattice electrons in a magnetic field. It moves on to explain topological phases of matter such as Chern insulators, two and three dimensional topological insulators, and Majorana p wave wires. Additionally, the book covers zero modes on vortices in topological superconductors, time reversal topological superconductors, and topological responses/field theory and topological indices. The book also analyzes recent topics in condensed matter theory and concludes by surveying active subfields of research such as insulators with point group symmetries and the stability of topological semimetals. Problems at the end of each chapter offer opportunities to test knowledge and engage with frontier research issues. Topological Insulators and Topological Superconductors will provide graduate students and researchers with the physical understanding and mathematical tools needed to embark on research in this rapidly evolving field.
author_names: Bogdan Andrei Bernevig
title: Topological Insulators and Topological Superconductors
year: 2013

abstract: We trained a large, deep convolutional neural network to classify the 1.2 million high resolution images in the ImageNet LSVRC 2010 contest into the 1000 different classes. On the test data, we achieved top 1 and top 5 error rates of 37.5% and 17.0% respectively, which is considerably better than the previous state of the art. The neural network, which has 60 million parameters and 650,000 neurons, consists of five convolutional layers, some of which are followed by max pooling layers, and three fully connected layers with a final 1000 way softmax. To make training faster, we used non saturating neurons and a very efficient GPU implementation of the convolution operation. To reduce overfitting in the fully connected layers we employed a recently developed regularization method called "dropout" that proved to be very effective. We also entered a variant of this model in the ILSVRC 2012 competition and achieved a winning top 5 test error rate of 15.3% compared to 26.2% achieved by the second best entry.
author_names: Alex Krizhevsky

Ilya Sutskever

Geoffrey E Hinton
title: ImageNet classification with deep convolutional neural networks
venue: Commun. ACM
year: 2012

abstract: Kondo insulators are a particularly simple type of heavy electron material, where a filled band of heavy quasiparticles gives rise to a narrow band insulator. Starting with the Anderson lattice Hamiltonian, we develop a topological classification of emergent band structures for Kondo insulators and show that these materials may host three dimensional topological insulating phases. We propose a general and practical prescription of calculating the Z(2) topological indices for various lattice structures. Experimental implications of the topological Kondo insulating behavior are discussed.
author_names: Maxim Dzero

Kai Sun

Victor M Galitski

Piers Coleman
title: Topological Kondo insulators.
venue: Physical review letters
year: 2010

abstract: The status of the insulators in power line can directly affect the reliability of the power transmission systems. Computer vision aided approaches have been widely applied in electric power systems. Inspecting the status of insulators from aerial images has been challenging due to the complex background and rapid view changing under different illumination conditions. In this paper, we propose a novel approach to inspect the insulators with Deep Convolutional Neural Networks (CNN) A CNN model with multi patch feature extraction method is applied to represent the status of insulators and a Support Vector Machine (SVM) is trained based on these features. A thorough evaluation is conducted on our insulator status dataset of six classes from real inspection videos. The experimental results show that a pre trained model for classification is more accurate than the shallow features by hand crafted. Our approach achieves 98.7095% mean Average Precision (mAP) in status classification. We also study the behavior of the neural activations of the convolutional layers. Different results vary with different fully connected layers, and interesting findings are discussed.
author_names: Zhenbing Zhao

Guozhi Xu

Yincheng Qi

Ning Liu

Tiefeng Zhang
title: Multi patch deep features for power line insulator status classification from aerial images
venue: 2016 International Joint Conference on Neural Networks (IJCNN)
year: 2016

abstract: We discuss a topological classification of insulators and superconductors in the presence of both (non spatial) discrete symmetries in the Altland Zirnbauer classification and spatial reflection symmetry in any spatial dimensions. By using the structure of bulk Dirac Hamiltonians of minimal matrix dimensions and explicit constructions of topological invariants, we provide the complete classification, which still has the same dimensional periodicities with the original Altland Zirnbauer classification. The classification of reflection symmetry protected topological insulators and superconductors depends crucially on the way reflection symmetry operation is realized. When a boundary is introduced, which is reflected into itself, these non trivial topological insulators and superconductors support gapless modes localized at the boundary.
author_names: Ching-Kai Chiu

Hong Yao

Shinsei Ryu
title: Classification of topological insulators and superconductors in the presence of reflection symmetry
year: 2013

abstract: Insulators are DNA sequences that control the interactions among genomic regulatory elements and act as chromatin boundaries. A thorough understanding of their location and function is necessary to address the complexities of metazoan gene regulation. We studied by ChIP chip the genome wide binding sites of 6 insulator associated proteins dCTCF, CP190, BEAF 32, Su(Hw) Mod(mdg4) and GAF to obtain the first comprehensive map of insulator elements in Drosophila embryos. We identify over 14,000 putative insulators, including all classically defined insulators. We find two major classes of insulators defined by dCTCF/CP190/BEAF 32 and Su(Hw) respectively. Distributional analyses of insulators revealed that particular sub classes of insulator elements are excluded between cis regulatory elements and their target promoters; divide differentially expressed, alternative, and divergent promoters; act as chromatin boundaries; are associated with chromosomal breakpoints among species; and are embedded within active chromatin domains. Together, these results provide a map demarcating the boundaries of gene regulatory units and a framework for understanding insulator function during the development and evolution of Drosophila.
author_names: Nicolas N Negre

Christopher D Brown

Parantu K Shah

Pouya Kheradpour

Carolyn A Morrison

Jorja G Henikoff

Xin Feng

K Ahmad

Steven Russell

Robert A H White

Lincoln Stein

Steven Henikoff

Manolis Kellis

Kevin P White
title: A Comprehensive Map of Insulator Elements for the Drosophila Genome
venue: PLoS genetics
year: 2010