The ultimate goal of genome assembly is a high-accuracy gapless genome.Here,we report a new assembly pipeline that is used to produce a gapless genome for the indica rice cultivar Minghui 63.The resulting 397.71-Mb fi...The ultimate goal of genome assembly is a high-accuracy gapless genome.Here,we report a new assembly pipeline that is used to produce a gapless genome for the indica rice cultivar Minghui 63.The resulting 397.71-Mb final assembly is composed of 12 contigs with a contig N50 size of 31.93 Mb.Each chromosome is represented by a single contig and the genomic sequences of all chromosomes are gapless.Quality evaluation of this gapless genome assembly showed that gene regions in our assembly have the highest completeness compared with the other 15 reported high-quality rice genomes.Further comparison with the japonica rice genome revealed that the gapless indica genome assembly contains more transposable elements(TEs)and segmental duplications(SDs),the latter of which produce many duplicated genes that can affect agronomic traits through dose effect or sub-/neo-functionalization.The insertion of TEs can also affect the expression of duplicated genes,which may drive the evolution of these genes.Furthermore,we found the expansion of nucleotide-binding site with leucine-rich repeat disease-resistance genes and cis-zeatin-O-glucosyltransferase growth-related genes in SDs in the gapless indica genome assembly,suggesting that SDs contribute to the adaptive evolution of rice disease resistance and developmental processes.Collectively,our findings suggest that active TEs and SDs synergistically contribute to rice genome evolution.展开更多
Topological materials and metamaterials opened new paradigms to create and manipulate phases of matter with unconventional properties.Topological D-class phases(TDPs)are archetypes of the ten-fold classification of to...Topological materials and metamaterials opened new paradigms to create and manipulate phases of matter with unconventional properties.Topological D-class phases(TDPs)are archetypes of the ten-fold classification of topological phases with particle-hole symmetry.In two dimensions,TDPs support propagating topological edge modes that simulate the elusive Majorana elementary particles.Furthermore,a piercing ofπ-flux Dirac-solenoids in TDPs stabilizes localized Majorana excitations that can be braided for the purpose of topological quantum computation.Such two-dimensional(2D)TDPs have been a focus in the research frontier,but their experimental realizations are still under debate.Here,with a novel design scheme,we realize 2D TDPs in an acoustic crystal by synthesizing both the particle-hole and fermion-like time reversal symmetries for a wide range of frequencies.The design scheme leverages an enriched unit cell structure with real-valued couplings that emulate the targeted Hamiltonian of TDPs with complex hoppings:A technique that could unlock the realization of all topological classes with passive metamaterials.In our experiments,we realize a pair of TDPs with opposite Chern numbers in two independent sectors that are connected by an intrinsic fermion-like timereversal symmetry built in the system.We measure the acoustic Majorana-like helical edge modes and visualize their robust topological transport,thus revealing the unprecedented D and DIII class topologies with direct evidence.Our study opens up a new pathway for the experimental realization of two fundamental classes of topological phases and may offer new insights in fundamental physics,materials science,and phononic information processing.展开更多
We study the acoustomagnetoelectric (AME) effect in two-dimensional graphene with an energy bandgap using the semiclassical Boltzmann transport equation within the hypersound regime, (where represents the acoustic wav...We study the acoustomagnetoelectric (AME) effect in two-dimensional graphene with an energy bandgap using the semiclassical Boltzmann transport equation within the hypersound regime, (where represents the acoustic wavenumber and is the mean free path of the electron). The Boltzmann transport equation and other relevant equations were solved analytically to obtain an expression for the AME current density, consisting of longitudinal and Hall components. Our numerical results indicate that both components of the AME current densities display oscillatory behaviour. Furthermore, geometric resonances and Weiss oscillations were each defined using the relationship between the current density and Surface Acoustic Wave (SAW) frequency and the inverse of the applied magnetic field, respectively. Our results show that the AME current density of bandgap graphene, which can be controlled to suit a particular electronic device application, is smaller than that of (gapless) graphene and is therefore, more suited for nanophotonic device applications.展开更多
Accurate genomic information is essential for advancing genetic breeding research in specific rice varieties.This study presented a gapless genome assembly of the indica rice cultivar Zhonghui 8015(ZH8015)using Pac Bi...Accurate genomic information is essential for advancing genetic breeding research in specific rice varieties.This study presented a gapless genome assembly of the indica rice cultivar Zhonghui 8015(ZH8015)using Pac Bio HiFi,Hi-C,and ONT(Oxford Nanopore Technologies)ultra-long sequencing technologies,annotating 43037 gene structures.Subsequently,utilizing this genome along with transcriptomic and metabolomic techniques,we explored ZH8015's response to brown planthopper(BPH)infestation.Continuous transcriptomic sampling indicated significant changes in gene expression levels around 48 h after BPH feeding.Enrichment analysis revealed particularly significant alterations in genes related to reactive oxygen species scavenging and cell wall formation.Metabolomic results demonstrated marked increases in levels of several monosaccharides,which are components of the cell wall and dramatic changes in flavonoid contents.Omics association analysis identified differentially expressed genes associated with key metabolites,shedding light on ZH8015's response to BPH infestation.In summary,this study constructed a reliable genome sequence resource for ZH8015,and the preliminary multi-omics results will guide future insect-resistant breeding research.展开更多
Layered van der Waals(vdW) topological materials, especially the recently discovered MnBi_(2)Te_(4)-family magnetic topological insulators(TIs), have aroused great attention. However, there has been a serious debate a...Layered van der Waals(vdW) topological materials, especially the recently discovered MnBi_(2)Te_(4)-family magnetic topological insulators(TIs), have aroused great attention. However, there has been a serious debate about whether the surface states are gapped or gapless for antiferromagnetic(AFM) TI MnBi_(2)Te_(4), which is crucial to the prospect of various magnetic topological phenomena. Here, a minimal three-Dirac-fermion approach is developed to generally describe topological surface states of nonmagnetic/magnetic vdW TIs under the modulation of the interlayer vdW gap. In particular, this approach is applied to address the controversial issues concerning the surface states of vdW AFM TIs. Remarkably, topologically protected gapless Dirac-cone surface states are found to arise due to a small expansion of the interlayer vdW gap on the surface, when the Chern number equals zero for the surface ferromagnetic layer;while the surface states remain gapped in all other cases. These results are further confirmed by our first-principles calculations on AFM TI MnBi_(2)Te_(4). The theorectically discovered gapless Dirac-cone states provide a unique mechanism for understanding the puzzle of the experimentally observed gapless surface states in MnBi_(2)Te_(4).This work also provides a promising way for experiments to realize the intrinsic magnetic quantum anomalous Hall efect in MnBi_(2)Te_(4) films with a large energy gap.展开更多
Actinidia eriantha is one of the species of kiwifruit with a particularly high ascorbic acid (AsA) content.However, the molecular mechanism driving AsA richness in fruit remains unclear.In order to reveal the molecula...Actinidia eriantha is one of the species of kiwifruit with a particularly high ascorbic acid (AsA) content.However, the molecular mechanism driving AsA richness in fruit remains unclear.In order to reveal the molecular mechanism of AsA richness in A. eriantha, this study constructed a regulatory network related to AsA metabolism by combining genomics,metabolomics and transcriptomics.We assembled a high-quality genome of A. eriantha ‘Ganlv 1’ with only five remaining gaps.The assembly is comprised of 29 pseudochromosomes with a total size of 615.95 Mb, and contig N50 of 20.35 Mb.Among them,24 of the pseudochromosomes were obtained directly from telomere-to-telomere.The LTR assembly index score and consensus quality value were 21.34 and 39.90%, respectively.Subsequently, 61 metabolites and 2 092genes were found to be differentially accumulated/expressed during fruit development by metabolome and transcriptome assays, respectively.AsA metabolism and the cyclic regeneration pathway were found to have high expression levels throughout fruit growth and development,suggesting its crucial role in the regulation of AsA.Furthermore,the AsA contents are highly associated with ascorbate peroxidase genes.The genome obtained in this study provides genomic resources for the genetic and breeding research ofA. eriantha, and the constructed regulatory network can provide a public data platform for future research on kiwifruit.展开更多
<i>Bacillus thuringiensis</i> (Bt) parasporal crystal proteins were well known to be toxic to certain insects and cytocidal activity against various human cancer cells. Bt serovar <i>coreanensis</...<i>Bacillus thuringiensis</i> (Bt) parasporal crystal proteins were well known to be toxic to certain insects and cytocidal activity against various human cancer cells. Bt serovar <i>coreanensis</i> ST7, non-pathogenic to insects and non-hemolytic, has an important parasporin, PS4Aa1 (Cry45Aa1), with potential toxicity to human cancer cells. In this study, we reported the feature of complete genome sequence and the cluster of orthologous groups of proteins function classification of ST7. Meanwhile, the evolutionary of ST7 was also studied. The genome data of ST7 will strongly contribute to a better understanding of the genomic diversity and evolution, and enrich the Bt genome database.展开更多
Using Green＇s function method, we investigate the spin transport properties of armchair graphene nanoribbons （AG- NRs） under magnetic field and uniaxial strain. Our results show that it is very difficult to transfo...Using Green＇s function method, we investigate the spin transport properties of armchair graphene nanoribbons （AG- NRs） under magnetic field and uniaxial strain. Our results show that it is very difficult to transform narrow AGNRs directly from semiconductor to spin gapless semiconductors （SGS） by applying magnetic fields. However, as a uniaxial strain is exerted on the nanoribbons, the AGNRs can transform to SGS by a small magnetic field. The combination mode be- tween magnetic field and uniaxial strain displays a nonmonotonic arch-pattern relationship. In addition, we find that the combination mode is associated with the widths of nanoribbons, which exhibits group behaviors.展开更多
In almost all previous works, the hyperbolic dispersion surfaces of the central proper quadrics have been crudely derived from the degree of reduction from the bi-quadratic equation by use of some roughly indefinable ...In almost all previous works, the hyperbolic dispersion surfaces of the central proper quadrics have been crudely derived from the degree of reduction from the bi-quadratic equation by use of some roughly indefinable approximate relations. Moreover, neglecting the high symmetry of the hyperbola, both the branches have been approximated on the asymmetric surfaces composed of a pair of a branch of the hyperbola and a vertex of the ellipse without the presentation of reasonable evidence. Based upon the same dispersion surfaces equation, a new original gapless dispersion surfaces could be rigorously introduced without crude omission of even a term in the bi-quadratic equation based upon usual analogy with the extended band theory of solid as the close approximation to the truth.展开更多
Quantum fluctuations from frustration can trigger quantum spin liquids(QSLs) at zero temperature.However, it is unclear how thermal fluctuations affect a QSL. We employ state-of-the-art tensor network-based methods to...Quantum fluctuations from frustration can trigger quantum spin liquids(QSLs) at zero temperature.However, it is unclear how thermal fluctuations affect a QSL. We employ state-of-the-art tensor network-based methods to explore the ground state and thermodynamic properties of the spin-1=2 kagomé Heisenberg antiferromagnet(KHA). Its ground state is shown to be consistent with a gapless QSL by observing the absence of zero-magnetization plateau as well as the algebraic behaviors of susceptibility and specific heat at low temperatures, respectively. We show that there exists an algebraic paramagnetic liquid(APL) that possesses both the paramagnetic properties and the algebraic behaviors inherited from the QSL. The APL is induced under the interplay between quantum fluctuations from geometrical frustration and thermal fluctuations. By studying the temperature-dependent behaviors of specific heat and magnetic susceptibility, a finite-temperature phase diagram in a magnetic field is suggested, where various phases are identified. This present study gains useful insight into the thermodynamic properties of the spin-1/2 KHA with or without a magnetic field and is helpful for relevant experimental studies.展开更多
We study the dynamical quantum phase transitions(DQPTs)in the XY chains with the Dzyaloshinskii-Moriya interaction and the XZY-YZX type of three-site interaction after a sudden quench.Both the models can be mapped to ...We study the dynamical quantum phase transitions(DQPTs)in the XY chains with the Dzyaloshinskii-Moriya interaction and the XZY-YZX type of three-site interaction after a sudden quench.Both the models can be mapped to the spinless free fermion models by the Jordan-Wigner and Bogoliubov transformations with the form■where the quasiparticle excitation spectraεkmay be smaller than 0 for some k and are asymmetrical■It is found that the factors of Loschmidt echo equal 1 for some k corresponding to the quasiparticle excitation spectra of the pre-quench Hamiltonian satisfyingε_(k)·ε_(-k)<0,when the quench is from the gapless phase.By considering the quench from different ground states,we obtain the conditions for the occurrence of DQPTs for the general XY chains with gapless phase,and find that the DQPTs may not occur in the quench across the quantum phase transitions regardless of whether the quench is from the gapless phase to gapped phase or from the gapped phase to gapless phase.This is different from the DQPTs in the case of quench from the gapped phase to gapped phase,in which the DQPTs will always appear.Moreover,we analyze the different reasons for the absence of DQPTs in the quench from the gapless phase and the gapped phase.The conclusion can also be extended to the general quantum spin chains.展开更多
We study the effect of electron-phonon （e-ph） interaction on the elastic and inelastic electronic transport of a nanowire connected to two simple rigid leads within the tight-binding and harmonic approximations. The...We study the effect of electron-phonon （e-ph） interaction on the elastic and inelastic electronic transport of a nanowire connected to two simple rigid leads within the tight-binding and harmonic approximations. The model is constructed using Green＇s function and multi-channel techniques, taking into account the local and nonlocal e-ph interactions. Then, we examine the model for the gapless （simple chain） and gapped （PA-like nanowire） systems. The results show that the tunneling conductance is improved by the e-ph interaction in both local and nonlocal regimes, while for the resonance conductance, the coherent part mainly decreases and the incoherent part increases. At the corresponding energies which depend on the phonon frequency, two dips in the elastic and two peaks in the inelastic conductance spectra appear. The reason is the absorption of the phonon by the electron in transition into inelastic channels.展开更多
The gapless Weyl superfluid has been widely studied in the three-dimensional ultracold fermionic superfluid. In contrast to Weyl superfluid, there exists another kind of gapless superfluid with topologically protected...The gapless Weyl superfluid has been widely studied in the three-dimensional ultracold fermionic superfluid. In contrast to Weyl superfluid, there exists another kind of gapless superfluid with topologically protected nodal lines, which can be regarded as the superttuid counterpart of nodal line semimetal in the condensed matter physics, just as Weyl superfluid with Weyl semimetal. In this paper we study the ground states of the cold fermionic gases in cubic optical lattices with one-dimensional spin-orbit coupling and transverse Zeeman field and map out the topological phase diagram of the system. We demonstrate that in addition to a fully gapped topologically trivial phase, some different nodal line superfluid phases appear when the Zeeman field is adjusted. The presence of topologically stable nodal lines implies the dispersionless zero-energy fiat band in a finite region of the surface Brillouin zone. Experimentally these nodal line superfluid states can be detected via the momentum-resolved radio-frequency spectroscopy. The nodal line topological superfluid provide fertile grounds for exploring exotic quantum matters in the context of ultraeold atoms.展开更多
基金This study was supported by the National Natural Science Foundation of China(NSFC,nos.31770331 and 31970318)Guangdong Basic and Applied Basic Research Foundation(no.2020B1515120023).
文摘The ultimate goal of genome assembly is a high-accuracy gapless genome.Here,we report a new assembly pipeline that is used to produce a gapless genome for the indica rice cultivar Minghui 63.The resulting 397.71-Mb final assembly is composed of 12 contigs with a contig N50 size of 31.93 Mb.Each chromosome is represented by a single contig and the genomic sequences of all chromosomes are gapless.Quality evaluation of this gapless genome assembly showed that gene regions in our assembly have the highest completeness compared with the other 15 reported high-quality rice genomes.Further comparison with the japonica rice genome revealed that the gapless indica genome assembly contains more transposable elements(TEs)and segmental duplications(SDs),the latter of which produce many duplicated genes that can affect agronomic traits through dose effect or sub-/neo-functionalization.The insertion of TEs can also affect the expression of duplicated genes,which may drive the evolution of these genes.Furthermore,we found the expansion of nucleotide-binding site with leucine-rich repeat disease-resistance genes and cis-zeatin-O-glucosyltransferase growth-related genes in SDs in the gapless indica genome assembly,suggesting that SDs contribute to the adaptive evolution of rice disease resistance and developmental processes.Collectively,our findings suggest that active TEs and SDs synergistically contribute to rice genome evolution.
基金the support from the National Key R&D Program of China(2022YFA1404400)the National Natural Science Foundation of China(12125504 and 12074281)+5 种基金the support from the National Natural Science Foundation of China(12047541)the Gusu Leading Innovation Scientists Program of Suzhou City,and the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutionsthe Research Fund of Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology(2020B1212030010)support from the US National Science Foundation(CMMI2131759)support from the US National Science Foundation(DMR-1823800 and CMMI-2131760)the U.S.Army Research Office through contract W911NF-23-1-0127。
文摘Topological materials and metamaterials opened new paradigms to create and manipulate phases of matter with unconventional properties.Topological D-class phases(TDPs)are archetypes of the ten-fold classification of topological phases with particle-hole symmetry.In two dimensions,TDPs support propagating topological edge modes that simulate the elusive Majorana elementary particles.Furthermore,a piercing ofπ-flux Dirac-solenoids in TDPs stabilizes localized Majorana excitations that can be braided for the purpose of topological quantum computation.Such two-dimensional(2D)TDPs have been a focus in the research frontier,but their experimental realizations are still under debate.Here,with a novel design scheme,we realize 2D TDPs in an acoustic crystal by synthesizing both the particle-hole and fermion-like time reversal symmetries for a wide range of frequencies.The design scheme leverages an enriched unit cell structure with real-valued couplings that emulate the targeted Hamiltonian of TDPs with complex hoppings:A technique that could unlock the realization of all topological classes with passive metamaterials.In our experiments,we realize a pair of TDPs with opposite Chern numbers in two independent sectors that are connected by an intrinsic fermion-like timereversal symmetry built in the system.We measure the acoustic Majorana-like helical edge modes and visualize their robust topological transport,thus revealing the unprecedented D and DIII class topologies with direct evidence.Our study opens up a new pathway for the experimental realization of two fundamental classes of topological phases and may offer new insights in fundamental physics,materials science,and phononic information processing.
文摘We study the acoustomagnetoelectric (AME) effect in two-dimensional graphene with an energy bandgap using the semiclassical Boltzmann transport equation within the hypersound regime, (where represents the acoustic wavenumber and is the mean free path of the electron). The Boltzmann transport equation and other relevant equations were solved analytically to obtain an expression for the AME current density, consisting of longitudinal and Hall components. Our numerical results indicate that both components of the AME current densities display oscillatory behaviour. Furthermore, geometric resonances and Weiss oscillations were each defined using the relationship between the current density and Surface Acoustic Wave (SAW) frequency and the inverse of the applied magnetic field, respectively. Our results show that the AME current density of bandgap graphene, which can be controlled to suit a particular electronic device application, is smaller than that of (gapless) graphene and is therefore, more suited for nanophotonic device applications.
基金supported by the Chinese Academy of Agricultural Sciences Innovation Project(Grant No.CAASASTIP-2013CNRRI)Fundamental Research Funds for Central Public Welfare Research Institutes of Chinese Rice Research Institute(Grant No.CPSIBRF-CNRRI-202102)。
文摘Accurate genomic information is essential for advancing genetic breeding research in specific rice varieties.This study presented a gapless genome assembly of the indica rice cultivar Zhonghui 8015(ZH8015)using Pac Bio HiFi,Hi-C,and ONT(Oxford Nanopore Technologies)ultra-long sequencing technologies,annotating 43037 gene structures.Subsequently,utilizing this genome along with transcriptomic and metabolomic techniques,we explored ZH8015's response to brown planthopper(BPH)infestation.Continuous transcriptomic sampling indicated significant changes in gene expression levels around 48 h after BPH feeding.Enrichment analysis revealed particularly significant alterations in genes related to reactive oxygen species scavenging and cell wall formation.Metabolomic results demonstrated marked increases in levels of several monosaccharides,which are components of the cell wall and dramatic changes in flavonoid contents.Omics association analysis identified differentially expressed genes associated with key metabolites,shedding light on ZH8015's response to BPH infestation.In summary,this study constructed a reliable genome sequence resource for ZH8015,and the preliminary multi-omics results will guide future insect-resistant breeding research.
基金supported by the National Key Projects for Research and Development of China (Grant Nos. 2021YFA1400400, 2017YFA0303203, and 2022YFA1403602)the Fundamental Research Funds for the Central Universities (Grant No. 020414380185)+3 种基金the Natural Science Foundation of Jiangsu Province (Grant No. BK20200007)the National Natural Science Foundation of China (Grant Nos. 12074181, 12104217, 11834006, and 12174182)the Fok Ying-Tong Education Foundation of China (Grant No. 161006)supported by the program A/B for Outstanding PhD candidate of Nanjing University。
文摘Layered van der Waals(vdW) topological materials, especially the recently discovered MnBi_(2)Te_(4)-family magnetic topological insulators(TIs), have aroused great attention. However, there has been a serious debate about whether the surface states are gapped or gapless for antiferromagnetic(AFM) TI MnBi_(2)Te_(4), which is crucial to the prospect of various magnetic topological phenomena. Here, a minimal three-Dirac-fermion approach is developed to generally describe topological surface states of nonmagnetic/magnetic vdW TIs under the modulation of the interlayer vdW gap. In particular, this approach is applied to address the controversial issues concerning the surface states of vdW AFM TIs. Remarkably, topologically protected gapless Dirac-cone surface states are found to arise due to a small expansion of the interlayer vdW gap on the surface, when the Chern number equals zero for the surface ferromagnetic layer;while the surface states remain gapped in all other cases. These results are further confirmed by our first-principles calculations on AFM TI MnBi_(2)Te_(4). The theorectically discovered gapless Dirac-cone states provide a unique mechanism for understanding the puzzle of the experimentally observed gapless surface states in MnBi_(2)Te_(4).This work also provides a promising way for experiments to realize the intrinsic magnetic quantum anomalous Hall efect in MnBi_(2)Te_(4) films with a large energy gap.
基金supported by the National Natural Science Foundation of China (32160692 and 31760559)the Key Research and Development Plan from Jiangxi Science and Technology Department, China (20192ACB60002)。
文摘Actinidia eriantha is one of the species of kiwifruit with a particularly high ascorbic acid (AsA) content.However, the molecular mechanism driving AsA richness in fruit remains unclear.In order to reveal the molecular mechanism of AsA richness in A. eriantha, this study constructed a regulatory network related to AsA metabolism by combining genomics,metabolomics and transcriptomics.We assembled a high-quality genome of A. eriantha ‘Ganlv 1’ with only five remaining gaps.The assembly is comprised of 29 pseudochromosomes with a total size of 615.95 Mb, and contig N50 of 20.35 Mb.Among them,24 of the pseudochromosomes were obtained directly from telomere-to-telomere.The LTR assembly index score and consensus quality value were 21.34 and 39.90%, respectively.Subsequently, 61 metabolites and 2 092genes were found to be differentially accumulated/expressed during fruit development by metabolome and transcriptome assays, respectively.AsA metabolism and the cyclic regeneration pathway were found to have high expression levels throughout fruit growth and development,suggesting its crucial role in the regulation of AsA.Furthermore,the AsA contents are highly associated with ascorbate peroxidase genes.The genome obtained in this study provides genomic resources for the genetic and breeding research ofA. eriantha, and the constructed regulatory network can provide a public data platform for future research on kiwifruit.
文摘<i>Bacillus thuringiensis</i> (Bt) parasporal crystal proteins were well known to be toxic to certain insects and cytocidal activity against various human cancer cells. Bt serovar <i>coreanensis</i> ST7, non-pathogenic to insects and non-hemolytic, has an important parasporin, PS4Aa1 (Cry45Aa1), with potential toxicity to human cancer cells. In this study, we reported the feature of complete genome sequence and the cluster of orthologous groups of proteins function classification of ST7. Meanwhile, the evolutionary of ST7 was also studied. The genome data of ST7 will strongly contribute to a better understanding of the genomic diversity and evolution, and enrich the Bt genome database.
基金supported by the National Basic Research Program of China(Grant No.2012CB921303)the National Natural Science Foundation of China(Grant Nos.51172191,11074211,11074213,51006086,and 51176161)the Joint Funds of the Natural Science Foundation of Hunan Province,China(Grant No.10JJ9001)
文摘Using Green＇s function method, we investigate the spin transport properties of armchair graphene nanoribbons （AG- NRs） under magnetic field and uniaxial strain. Our results show that it is very difficult to transform narrow AGNRs directly from semiconductor to spin gapless semiconductors （SGS） by applying magnetic fields. However, as a uniaxial strain is exerted on the nanoribbons, the AGNRs can transform to SGS by a small magnetic field. The combination mode be- tween magnetic field and uniaxial strain displays a nonmonotonic arch-pattern relationship. In addition, we find that the combination mode is associated with the widths of nanoribbons, which exhibits group behaviors.
文摘In almost all previous works, the hyperbolic dispersion surfaces of the central proper quadrics have been crudely derived from the degree of reduction from the bi-quadratic equation by use of some roughly indefinable approximate relations. Moreover, neglecting the high symmetry of the hyperbola, both the branches have been approximated on the asymmetric surfaces composed of a pair of a branch of the hyperbola and a vertex of the ellipse without the presentation of reasonable evidence. Based upon the same dispersion surfaces equation, a new original gapless dispersion surfaces could be rigorously introduced without crude omission of even a term in the bi-quadratic equation based upon usual analogy with the extended band theory of solid as the close approximation to the truth.
基金supported in part by the National Key R&D Program of China (2018YFA0305800)the National Natural Science Foundation of China (14474279 and 11834014)+5 种基金and the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB28000000 and XDB07010100)SJR was supported by ERC AdG OSYRIS (ERC-2013-AdG Grant No. 339106)Spanish Ministry MINECO (National Plan 15 Grant: FISICATEAMO No. FIS201679508-P, SEVERO OCHOA No. SEV-2015-0522)Generalitat de Catalunya (AGAUR Grant No. 2017 SGR 1341 and CERCA/Program)Fundació Privada Cellex, EU FETPRO QUIC (H2020-FETPROACT2014 No. 641122)the National Science Centre, and PolandSymfonia Grant No. 2016/20/W/ST4/00314
文摘Quantum fluctuations from frustration can trigger quantum spin liquids(QSLs) at zero temperature.However, it is unclear how thermal fluctuations affect a QSL. We employ state-of-the-art tensor network-based methods to explore the ground state and thermodynamic properties of the spin-1=2 kagomé Heisenberg antiferromagnet(KHA). Its ground state is shown to be consistent with a gapless QSL by observing the absence of zero-magnetization plateau as well as the algebraic behaviors of susceptibility and specific heat at low temperatures, respectively. We show that there exists an algebraic paramagnetic liquid(APL) that possesses both the paramagnetic properties and the algebraic behaviors inherited from the QSL. The APL is induced under the interplay between quantum fluctuations from geometrical frustration and thermal fluctuations. By studying the temperature-dependent behaviors of specific heat and magnetic susceptibility, a finite-temperature phase diagram in a magnetic field is suggested, where various phases are identified. This present study gains useful insight into the thermodynamic properties of the spin-1/2 KHA with or without a magnetic field and is helpful for relevant experimental studies.
基金supported by the National Natural Science Foundation of China(Grant Nos.11975126 and 11575087)。
文摘We study the dynamical quantum phase transitions(DQPTs)in the XY chains with the Dzyaloshinskii-Moriya interaction and the XZY-YZX type of three-site interaction after a sudden quench.Both the models can be mapped to the spinless free fermion models by the Jordan-Wigner and Bogoliubov transformations with the form■where the quasiparticle excitation spectraεkmay be smaller than 0 for some k and are asymmetrical■It is found that the factors of Loschmidt echo equal 1 for some k corresponding to the quasiparticle excitation spectra of the pre-quench Hamiltonian satisfyingε_(k)·ε_(-k)<0,when the quench is from the gapless phase.By considering the quench from different ground states,we obtain the conditions for the occurrence of DQPTs for the general XY chains with gapless phase,and find that the DQPTs may not occur in the quench across the quantum phase transitions regardless of whether the quench is from the gapless phase to gapped phase or from the gapped phase to gapless phase.This is different from the DQPTs in the case of quench from the gapped phase to gapped phase,in which the DQPTs will always appear.Moreover,we analyze the different reasons for the absence of DQPTs in the quench from the gapless phase and the gapped phase.The conclusion can also be extended to the general quantum spin chains.
基金Project supported by the Iranian Nanotechnology Initiativesupported by Shahrekord University through a research fund
文摘We study the effect of electron-phonon （e-ph） interaction on the elastic and inelastic electronic transport of a nanowire connected to two simple rigid leads within the tight-binding and harmonic approximations. The model is constructed using Green＇s function and multi-channel techniques, taking into account the local and nonlocal e-ph interactions. Then, we examine the model for the gapless （simple chain） and gapped （PA-like nanowire） systems. The results show that the tunneling conductance is improved by the e-ph interaction in both local and nonlocal regimes, while for the resonance conductance, the coherent part mainly decreases and the incoherent part increases. At the corresponding energies which depend on the phonon frequency, two dips in the elastic and two peaks in the inelastic conductance spectra appear. The reason is the absorption of the phonon by the electron in transition into inelastic channels.
基金Supported by National Natural Science Foundation of China under Grant Nos.11547047 and 11504143
文摘The gapless Weyl superfluid has been widely studied in the three-dimensional ultracold fermionic superfluid. In contrast to Weyl superfluid, there exists another kind of gapless superfluid with topologically protected nodal lines, which can be regarded as the superttuid counterpart of nodal line semimetal in the condensed matter physics, just as Weyl superfluid with Weyl semimetal. In this paper we study the ground states of the cold fermionic gases in cubic optical lattices with one-dimensional spin-orbit coupling and transverse Zeeman field and map out the topological phase diagram of the system. We demonstrate that in addition to a fully gapped topologically trivial phase, some different nodal line superfluid phases appear when the Zeeman field is adjusted. The presence of topologically stable nodal lines implies the dispersionless zero-energy fiat band in a finite region of the surface Brillouin zone. Experimentally these nodal line superfluid states can be detected via the momentum-resolved radio-frequency spectroscopy. The nodal line topological superfluid provide fertile grounds for exploring exotic quantum matters in the context of ultraeold atoms.
