Quantum Criticality with Emergent Symmetry in the Extended Shastry-Sutherland Model.

Motivated by the novel phenomena observed in the layered material SrCu_{2}(BO_{3})_{2}, the Shastry-Sutherland model (SSM) has been extensively studied as the minimal model for SrCu_{2}(BO_{3})_{2}. However, the nature of its quantum phase transition from the plaquette valence-bond solid to antiferromagnetic phase is under fierce debate, posing a challenge to understand the underlying quantum criticality. Via the state-of-the-art tensor network simulations, we study the ground state of the SSM on large-scale size up to 20×20 sites.

Emergent symmetry in quantum phase transition: From deconfined quantum critical point to gapless quantum spin liquid.

The emergence of exotic quantum phenomena in frustrated magnets is rapidly driving the development of quantum many-body physics, raising fundamental questions on the nature of quantum phase transitions. Here we unveil the behaviour of emergent symmetry involving two extraordinarily representative phenomena, i.e.

Gapless quantum spin liquid and global phase diagram of the spin-1/2 J-J square antiferromagnetic Heisenberg model.

The nature of the zero-temperature phase diagram of the spin-1/2J-J Heisenberg model on a square lattice has been debated in the past three decades, and it remains one of the fundamental problems unsettled in the study of quantum many-body theory. By using the state-of-the-art tensor network method, specifically, the finite projected entangled pair state (PEPS) algorithm, to simulate the global phase diagram of the J-J Heisenberg model up to 24×24 sites, we provide very solid evidences to show that the nature of the intermediate nonmagnetic phase is a gapless quantum spin liquid (QSL), whose spin-spin and dimer-dimer correlations both decay with a power law behavior. There also exists a valence-bond solid (VBS) phase in a very narrow region 0.

Classification of topological phases in one dimensional interacting non-Hermitian systems and emergent unitarity.

Topological phases in non-Hermitian systems have become fascinating subjects recently. In this paper, we attempt to classify topological phases in 1D interacting non-Hermitian systems. We begin with the non-Hermitian generalization of the Su-Schrieffer-Heeger (SSH) model and discuss its many-body topological Berry phase, which is well defined for all interacting quasi-Hermitian systems (non-Hermitian systems that have real energy spectrum).

Non-Abelian three-loop braiding statistics for 3D fermionic topological phases.

Fractional statistics is one of the most intriguing features of topological phases in 2D. In particular, the so-called non-Abelian statistics plays a crucial role towards realizing topological quantum computation. Recently, the study of topological phases has been extended to 3D and it has been proposed that loop-like extensive objects can also carry fractional statistics.

Anomalous Symmetry Protected Topological States in Interacting Fermion Systems.

The classification and construction of symmetry protected topological (SPT) phases have been intensively studied in interacting systems recently. To our surprise, in interacting fermion systems, there exists a new class of the so-called anomalous SPT (ASPT) states which are only well defined on the boundary of a trivial fermionic bulk system. We first demonstrate the essential idea by considering an anomalous topological superconductor with time-reversal symmetry T^{2}=1 in 2D.

Loop Optimization for Tensor Network Renormalization.

We introduce a tensor renormalization group scheme for coarse graining a two-dimensional tensor network that can be successfully applied to both classical and quantum systems on and off criticality. The key innovation in our scheme is to deform a 2D tensor network into small loops and then optimize the tensors on each loop. In this way, we remove short-range entanglement at each iteration step and significantly improve the accuracy and stability of the renormalization flow.

Field-theory representation of gauge-gravity symmetry-protected topological invariants, group cohomology, and beyond.

The challenge of identifying symmetry-protected topological states (SPTs) is due to their lack of symmetry-breaking order parameters and intrinsic topological orders. For this reason, it is impossible to formulate SPTs under Ginzburg-Landau theory or probe SPTs via fractionalized bulk excitations and topology-dependent ground state degeneracy. However, the partition functions from path integrals with various symmetry twists are universal SPT invariants, fully characterizing SPTs.

Microscopic realization of two-dimensional bosonic topological insulators.

It is well known that a bosonic Mott insulator can be realized by condensing vortices of a boson condensate. Usually, a vortex becomes an antivortex (and vice versa) under time reversal symmetry, and the condensation of vortices results in a trivial Mott insulator. However, if each vortex or antivortex interacts with a spin trapped at its core, the time reversal transformation of the composite vortex operator will contain an extra minus sign.

Application of Auto-regressive Linear Model in Understanding the Effect of Climate on Malaria Vectors Dynamics in the Three Gorges Reservoir.

It is important to understand the dynamics of malaria vectors in implementing malaria control strategies. Six villages were selected from different sections in the Three Gorges Reservoir for exploring the relationship between the climatic factors and its malaria vector density from 1997 to 2007 using the auto-regressive linear model regression method. The result indicated that both temperature and precipitation were better modeled as quadratic rather than linearly related to the density of Anopheles sinensis.

Topological response theory of Abelian symmetry-protected topological phases in two dimensions.

It has been shown that the symmetry-protected topological (SPT) phases with finite Abelian symmetries can be described by Chern-Simons field theory. We propose a topological response theory to uniquely identify the SPT orders, which allows us to obtain a systematic scheme to classify bosonic SPT phases with any finite Abelian symmetry group. We point out that even for finite Abelian symmetry, there exist bosonic SPT phases beyond the current Chern-Simons theory framework.

Constructing a gapless spin-liquid state for the spin-1/2 J(1)-J(2) Heisenberg model on a square lattice.

We construct a class of projected entangled pair states which is exactly the resonating valence bond wave functions endowed with both short range and long range valence bonds. With an energetically preferred resonating valence bond pattern, the wave function is simplified to live in a one-parameter variational space. We tune this variational parameter to minimize the energy for the frustrated spin-1/2 J(1)-J(2) antiferromagnetic Heisenberg model on the square lattice.

Symmetry-protected topological orders in interacting bosonic systems.

Symmetry-protected topological (SPT) phases are bulk-gapped quantum phases with symmetries, which have gapless or degenerate boundary states as long as the symmetries are not broken. The SPT phases in free fermion systems, such as topological insulators, can be classified; however, it is not known what SPT phases exist in general interacting systems. We present a systematic way to construct SPT phases in interacting bosonic systems.

[Impact of pesticide use on the density of Anopheles anthropophagus and malaria incidence].

Objective: To investigate the impact of the application of chemical pesticides on the distribution of Anopheles anthropophagus in rice fields and the malaria incidence.

Method: Twenty-four villages from 16 counties in the provinces of Zhejiang, Sichuan and Guangxi were chosen for the surveys in the period of 1983-1987. For the survey of An.

[Investigation on anopheline species in Chayu County, Linzhi Prefecture of Tibet Autonomous Region].

Objective: To investigate Anopheline species in Chayu County of Linzhi Prefecture, Tibet.

Methods: Four natural villages in Chayu County were selected in this study in 2010. The methods of overnight/semi-overnight trapping indoor and outdoor human-bait, and overnight trapping with light traps were used, and all the Anopheline mosquitoes were confirmed by morphological characteristics.

Non-abelian quantum Hall effect in topological flat bands.

Inspired by the recent theoretical discovery of robust fractional topological phases without a magnetic field, we search for the non-abelian quantum Hall effect in lattice models with topological flat bands. Through extensive numerical studies on the Haldane model with three-body hard-core bosons loaded into a topological flat band, we find convincing numerical evidence of a stable ν=1 bosonic non-abelian quantum Hall effect, with the characteristic threefold quasidegeneracy of ground states on a torus, a quantized Chern number, and a robust spectrum gap. Moreover, the spectrum for two-quasihole states also shows a finite energy gap, with the number of states in the lower-energy sector satisfying the same counting rule as the Moore-Read pfaffian state.

Fractional quantum Hall effect of hard-core bosons in topological flat bands.

Recent proposals of topological flat band models have provided a new route to realize the fractional quantum Hall effect without Landau levels. We study hard-core bosons with short-range interactions in two representative topological flat band models, one of which is the well-known Haldane model (but with different parameters). We demonstrate that fractional quantum Hall states emerge with signatures of an even number of quasidegenerate ground states on a torus and a robust spectrum gap separating these states from the higher energy spectrum.

Fractional quantum Hall effect in the absence of Landau levels.

It is well known that the topological phenomena with fractional excitations, the fractional quantum Hall effect, will emerge when electrons move in Landau levels. Here we show the theoretical discovery of the fractional quantum Hall effect in the absence of Landau levels in an interacting fermion model. The non-interacting part of our Hamiltonian is the recently proposed topologically non-trivial flat-band model on a checkerboard lattice.

Gapped two-body hamiltonian whose unique ground state is universal for one-way quantum computation.

Many-body entangled quantum states studied in condensed matter physics can be primary resources for quantum information, allowing any quantum computation to be realized using measurements alone, on the state. Such a universal state would be remarkably valuable, if only it were thermodynamically stable and experimentally accessible, by virtue of being the unique ground state of a physically reasonable Hamiltonian made of two-body, nearest-neighbor interactions. We introduce such a state, composed of six-state particles on a hexagonal lattice, and describe a general method for analyzing its properties based on its projected entangled pair state representation.

[Morphology and habits of An. anthropophagus and its role in malaria transmission in Hengqin Island of Zhuhai City].

Objective: To study the morphology and ecological habits of An. anthropophagus and its role in malaria transmission in Hengqin Island of Zhuhai City, Guangdong Province.

Methods: Mosquitoes were captured through overnight/semi-overnight trapping with human and cattle baits as well as lamp-trapping.

[Evaluation on current malaria prevalence using capture-recapture method in national sentinel surveillance points malaria].

Objective: To explore the feasibility of using the capture-recapture method (CRM) for national malaria sentinel surveillance program and to evaluate the malaria prevalence at those points.

Methods: By CRM to compare data on malaria cases reported from national sentinel surveillance program and those from the registration of case report system (CRS). Analysis was made to express the difference regarding the number of cases in order to get the estimates and the incidence rate.

[Study on the thresholds of malaria transmission by Anopheles anthropophagus in Hubei Province].

Objective: To study the thresholds and potential of malaria transmission by Anopheles anthropophagus in Hubei Province and provide indicators for the disease surveillance, early warning, prevention and control in the locality.

Methods: From July to August 2001, field investigations on vectors and malaria situation were carried out in the village of Yanjiafan, Suizhou City, where the malaria incidence was high. The entomological investigations included the man-biting rate, the proportion of parous anophelines, the human blood index and the blood preference.

[Malaria situation in the People's Republic of China in 2002].

This summary was made on the basis of the annual reports of malaria control from the professional institutions in the 21 Provinces/Municipality/Autonomous Region (P/M/A). The number of malaria cases reported in the country was 35,298 in the year 2002 and the incidence rate was 0.348/10,000, an increase of 68.

[Sequence difference of ribosomal DNA second internal transcribed spacer in Anopheles minimus in different localities].

Objective: To compare the sequence difference of the ribosomal DNA second internal transcribed spacer (ITS2) in Anopheles minimus from Yunnan, Hainan, Guangxi of China and from Thailand.

Methods: Single mosquito's legs were digested to extract DNA; the rDNA-ITS2 region was amplified by specific primers and the PCR products were purified, sequenced and analysed.

Results: Two different kinds of ITS2 sequences, temporarily named as An.