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Search Results: 1 - 10 of 122590 matches for " Chong Wang "
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Bound states of three fermions forming symmetry-protected topological phases
Chong Wang
Physics , 2014, DOI: 10.1103/PhysRevB.91.245124
Abstract: We propose a simple theoretical construction of certain short-range entangled phases of interacting fermions, by putting the bound states of three fermions (which we refer to as clustons) into topological bands. We give examples in two and three dimensions, and show that they are distinct from any free fermion state. We further argue that these states can be viewed as combinations of certain free fermion topological states and bosonic symmetry-protected topological (SPT) states. This provides a conceptually simple understanding of various SPT phases, and the possibility of realizing them in cold atom systems. New parton constructions of these SPT phases in purely bosonic systems are proposed. We also discuss a related anomaly in two dimensional Dirac theories, which is the gravitational analogue of the parity anomaly.
The Approximation of Hermite Interpolation on the Weighted Mean Norm  [PDF]
Xin Wang, Chong Hu, Xiuxiu Ma
American Journal of Computational Mathematics (AJCM) , 2015, DOI: 10.4236/ajcm.2015.53033
Abstract: We research the simultaneous approximation problem of the higher-order Hermite interpolation based on the zeros of the second Chebyshev polynomials under weighted Lp-norm. The estimation is sharp.
Robust Semiparametric Optimal Testing Procedure for Multiple Normal Means
Peng Liu,Chong Wang
Journal of Probability and Statistics , 2012, DOI: 10.1155/2012/913560
Abstract: In high-dimensional gene expression experiments such as microarray and RNA-seq experiments, the number of measured variables is huge while the number of replicates is small. As a consequence, hypothesis testing is challenging because the power of tests can be very low after controlling multiple testing error. Optimal testing procedures with high average power while controlling false discovery rate are preferred. Many methods were constructed to achieve high power through borrowing information across genes. Some of these methods can be shown to achieve the optimal average power across genes, but only under a normal assumption of alternative means. However, the assumption of a normal distribution is likely violated in practice. In this paper, we propose a novel semiparametric optimal testing (SPOT) procedure for high-dimensional data with small sample size. Our procedure is more robust because it does not depend on any parametric assumption for the alternative means. We show that the proposed test achieves the maximum average power asymptotically as the number of tests goes to infinity. Both simulation study and the analysis of a real microarray data with spike-in probes show that the proposed SPOT procedure performs better when compared to other popularly applied procedures.
Local and global behavior for algorithms of solving equations
Xinghua Wang,Chong Li
Chinese Science Bulletin , 2001, DOI: 10.1007/BF03187252
Abstract: The theory of “point estimate” and the concept of “general convergence”, which were put forward by Smale in order to investigate the complexity of algorithms for solving equations, have been producing a deep impact on the research about the local behavior, the semi-local behavior and the global behavior of iteration methods. The criterion of point estimate introduced by him not only provides a tool for quantitative analysis of the local behavior but also motivates the establishing of the unified determination for the semi-local behavior. Studying the global behavior in the view of discrete dynamical system will lead to many profound research subjects and open up a rich and colorful prospect. In this review, we will make a summarization about the research progress and some applications in nonsmooth optimizations.
Lipschitz continuity of best approximations and Chebyshev centers
Chong Li,Xinghua Wang
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02898906
Abstract: The Lipschitz continuity results are given for best approximations and Chebyshev centers. Consequently, the open problem presented by Septycki and Vleck is solved completely.
Option contracts in fresh produce supply chain with circulation loss
Chong Wang,Xu Chen
Journal of Industrial Engineering and Management , 2013, DOI: 10.3926/jiem.667
Abstract: Purpose: The purpose of this paper is to investigate management decisions via option contracts in a two-stage supply chain in which a fresh produce supplier sells to a retailer, considering the circulation loss of the fresh produce. Design/methodology/approach: Authors propose a Stackelberg model to analyze the supply chain members’ decisions in the decentralized supply chain compared with the integrated one under the newsvendor framework. Findings: The results illustrate that there exists a unique optimal option order quantity for the retailer and a unique optimal option order price for the supplier giving certain conditions; furthermore, option contracts cannot coordinate the fresh produce supply chain when the retailer only orders options. Originality/value: Agricultural products especially fresh produce’s characteristics such as circulation loss and high risk are considered. Option contracts and game theory are combined to manage the fresh produce supply chain’s risk. The proposed tool and models are hoped to shed light to the future works in the field of supply chain risk management.
Boson topological insulators: A window into highly entangled quantum phases
Chong Wang,T. Senthil
Physics , 2013, DOI: 10.1103/PhysRevB.87.235122
Abstract: We study several aspects of the realization of global symmetries in highly entangled phases of quantum matter. Examples include gapped topological ordered phases, gapless quantum spin liquids and non-fermi liquid phases. An insightful window into such phases is provided by recent developments in the theory of short ranged entangled Symmetry Protected Topological (SPT) phases . First they generate useful no-go constraints on how global symmetry may be implemented in a highly entangled phase. Possible symmetry implementation in gapped topological phases and some proposed gapless spin/bose liquids are examined in this light. We show that some previously proposed spin liquid states for 2d quantum magnets do not in fact have consistent symmetry implementation unless they occur as the surface of a 3d SPT phase. A second SPT-based insight into highly entangled states is the development of a view point of such states as SPT phases of one of the emergent excitations. We describe this in the specific context of time reversal symmetric 3d U(1) quantum spin liquids with an emergent photon. Different such spin liquids are shown to be equivalent to different SPT insulating phases of the emergent monopole excitation of such phases. The highly entangled states also in turn enrich our understanding of SPT phases. We use the insights obtained from our results to provide an explicit construction of bosonic SPT phases in 3d in a system of coupled layers. This includes construction of a time reversal symmetric SPT state that is not currently part of the cohomology classification of such states.
Interacting fermionic topological insulators/superconductors in three dimensions
Chong Wang,T. Senthil
Physics , 2014, DOI: 10.1103/PhysRevB.89.195124
Abstract: Symmetry Protected Topological (SPT) phases are a minimal generalization of the concept of topological insulators to interacting systems. In this paper we describe the classification and properties of such phases for three dimensional(3D) electronic systems with a number of different symmetries. For symmetries representative of all classes in the famous 10-fold way of free fermion topological insulators/superconductors, we determine the stability to interactions. By combining with results on bosonic SPT phases we obtain a classification of electronic 3D SPT phases for these symmetries. In cases with a normal U(1) subgroup we show that this classification is complete. We describe the non-trivial surface and bulk properties of these states. In particular we discuss interesting correlated surface states that are not captured in a free fermion description. We show that in many, but not all cases, the surface can be gapped while preserving symmetry if it develops intrinsic topological order.
Fractionalized gapless quantum vortex liquids
Chong Wang,T. Senthil
Physics , 2014, DOI: 10.1103/PhysRevB.91.195109
Abstract: The standard theoretical approach to gapless spin liquid phases of two-dimensional frustrated quantum antiferromagnets invokes the concept of fermionic slave particles into which the spin fractionalizes. As an alternate we explore new kinds of gapless spin liquid phases in frustrated quantum magnets with XY anisotropy where the vortex of the spin fractionalizes into gapless itinerant fermions. The resulting gapless fractionalized vortex liquid phases are studied within a slave particle framework that is dual to the usual one. We demonstrate the stability of some such phases and describe their properties. We give an explicit construction in an XY-spin-1 system on triangular lattice, and interpret it as a critical phase in the vicinity of spin-nematic states.
Dual Dirac liquid on the surface of the electron topological insulator
Chong Wang,T. Senthil
Physics , 2015, DOI: 10.1103/PhysRevX.5.041031
Abstract: We discuss a non-fermi liquid gapless metallic surface state of the topological band insulator. It has an odd number of gapless Dirac fermions coupled to a non-compact U(1) gauge field. This can be viewed as a vortex dual to the conventional Dirac fermion surface state. This surface duality is a reflection of a bulk dual description discussed recently for the gauged topological insulator. All the other known surface states can be conveniently accessed from the dual Dirac liquid, including the surface quantum hall state, the Fu-Kane superconductor, the gapped symmetric topological order and the "composite Dirac liquid". We also discuss the physical properties of the dual Dirac liquid, and its connection to the half-filled Landau level.
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