We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two ty...We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.展开更多
We investigate the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons(APNRs) containing atomic vacancies with different distributions and concentrations using ab initio density fun...We investigate the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons(APNRs) containing atomic vacancies with different distributions and concentrations using ab initio density functional calculations. It is found that the atomic vacancies are easier to form and detain at the edge region rather than a random distribution through analyzing formation energy and diffusion barrier. The highly local defect states are generated at the vicinity of the Fermi level, and emerge a deep-to-shallow transformation as the width increases after introducing vacancies in APNRs.Moreover, the electrical transport of APNRs with vacancies is enhanced compared to that of the perfect counterparts. Our results provide a theoretical guidance for the further research and applications of PNRs through defect engineering.展开更多
We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum ...We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum channels of guided photons.The perfect mirror imposed by the finite end exerts a retarded feedback mechanism to allow for information backflow,which leads to NM dynamics.For the energy separation of the atom far away from the cutoff frequencies of transverse modes,the delay differential equations are obtained with single-excitation initial in the atom.Our attention is focused on the effects of multiple quantum channels involved in guiding photons on the degree of nonMarkovian behavior.An asymptotic value of the non-Markovianity N_(1)can be found as the atom–mirror distance is large enough,however,the asymptotic value of N_(2)of the atom interacting with the effective double-modes is lower than that of the atom interacting with the effective single-mode.We also show that N_(1)is a constant,and the analytical expression for N_(2)is related to the parameters associated with the modes,which is related to the interference of the two modes.展开更多
Layered transition metal dichalcogenides(TMDCs)gained widespread attention because of their electron-correlationrelated physics,such as charge density wave(CDW),superconductivity,etc.In this paper,we report the high-r...Layered transition metal dichalcogenides(TMDCs)gained widespread attention because of their electron-correlationrelated physics,such as charge density wave(CDW),superconductivity,etc.In this paper,we report the high-resolution angle-resolved photoemission spectroscopy(ARPES)studies on the electronic structure of Ti-doped 1T-Ti_(x)Ta_(1-x)S_(2) with different doping levels.We observe a flat band that originates from the formation of the star of David super-cell at the x=5%sample at the low temperature.With the increasing Ti doping levels,the flat band vanishes in the x=8%sample due to the extra hole carrier.We also find the band shift and variation of the CDW gap caused by the Ti-doping.Meanwhile,the band folding positions and the CDW vector g_(CDW)intact.Our ARPES results suggest that the localized flat band and the correlation effect in the 1T-TMDCs could be tuned by changing the filling factor through the doping electron or hole carriers.The Ti-doped 1T-Ti_(x)Ta_(1-x)S_(2) provides a platform to fine-tune the electronic structure evolution and a new insight into the strongly correlated physics in the TMDC materials.展开更多
Understanding the physical mechanism of structural stability and transition in various polytypes of layered transition metal dichalcogenides under the external stimulus is of crucial importance for their new applicati...Understanding the physical mechanism of structural stability and transition in various polytypes of layered transition metal dichalcogenides under the external stimulus is of crucial importance for their new applications.Here,we investigate the thickness-dependent structural properties of MoS2 under the condition of hydrostatic pressure in terms of bond relaxation and thermodynamics considerations.For both types of MoS2 structures,we find that the transition and metallization are significantly modulated by hydrostatic pressure and the number of layers.We establish a pressure-size phase diagram to address the transition mechanism.Our study not only provides insights into the thickness-dependent structural properties of MoS2,but also shows a theoretical guidance for the design and fabrication of MoS2-based devices.展开更多
We investigate few-photon scattering properties in two one-dimensional waveguides chirally coupled to a nonlinear cavity.The quantum states of scattered few photons are solved analytically via a real-space approach,an...We investigate few-photon scattering properties in two one-dimensional waveguides chirally coupled to a nonlinear cavity.The quantum states of scattered few photons are solved analytically via a real-space approach,and the solution indicates the few-photon reflection and transmission properties.When inputting two photons of equal energy to resonate with the cavity,the propagation characteristics of the two photons will be interesting,which is different from the previous anti-bunching effects with a quantum emitter.More importantly,when the total energy of the two incident photons equals the energy of a nonlinear cavity accommodating two photons,influence of the bound state will become larger to result in disappearance of antibunching effect.However,the bound state has no effect on probability of routing to another waveguide.展开更多
We investigate the entanglement dynamics of two distinguishable two-level systems(TLSs)characterized by energy differenceδlocated inside a rectangular hollow metallic waveguide of transverse dimensions a and b.The ef...We investigate the entanglement dynamics of two distinguishable two-level systems(TLSs)characterized by energy differenceδlocated inside a rectangular hollow metallic waveguide of transverse dimensions a and b.The effects of energy differenceδand the inter-TLS distance on the time evolution of the concurrence of the TLSs are examined in the single excitation subspace when the energy separation of the TLS is far away from the cutoff frequencies of the transverse mode.展开更多
Transition metal hydroxides/oxyhydroxides have recently emerged as highly active electrocatalysts for oxygen evolution reaction in alkaline water electrolysis,while have not yet been widely investigated for hydrogen e...Transition metal hydroxides/oxyhydroxides have recently emerged as highly active electrocatalysts for oxygen evolution reaction in alkaline water electrolysis,while have not yet been widely investigated for hydrogen evolution electrocatalysts owing to their unfavorable H*-adsorption,making it difficult to construct an overall-water-splitting cell for hydrogen production.In this work,we proposed a straightforward and effective approach to develop an efficient in-plane heterostructured CoOOH/Co(OH)_(2) catalyst via in-situ electrochemical dehydrogenation method,in which the dehydrogenated–CoOOH and Co(OH)_(2) at the surface synergistically boost the hydrogen evolution reaction(HER)kinetics in base as confirmed by high-resolution transmission electron microscope,synchrotron X-ray absorption spectroscopy,and electron energy loss spectroscopy.Due to the in-situ dehydrogenation of ultrathin Co(OH)_(2) nanosheets,the catalytic activity of the CoOOH/Co(OH)_(2) heterostructures is progressively improved,which exhibit outstanding hydrogen-evolving activity in base requiring a low overpotential of 132 m V to afford 10 m A/cm^(2)with very fast reaction kinetics after 60 h dehydrogenation.The gradually improved catalytic performance for the CoOOH/Co(OH)2is probably due to the enhanced H*-adsorption induced by the synergistic effect of heterostructures and better conductivity of Co OOH relative to electrically insulating Co(OH)_(2).This work will open the opportunity for a new family of transition metal hydroxides/oxyhydroxides as active HER catalysts,and also highlight the importance of using in situ techniques to construct precious metal-free efficient catalysts for alkaline hydrogen evolution.展开更多
Halide perovskites(ABX_(3)), as promising candidates for solar cell photovoltaic devices, have recently attracted increasing research interest [1-3], but many issues remain unsolved for their practical applications. O...Halide perovskites(ABX_(3)), as promising candidates for solar cell photovoltaic devices, have recently attracted increasing research interest [1-3], but many issues remain unsolved for their practical applications. One such issue is their poor stability, which largely reduces device lifetime and efficiency [4]. In recent decades, using inorganic ions or organic molecules for replacement or alloying the A-site atoms in halide perovskites has improved thermodynamic stability to some extent.展开更多
Dear Editor,Herpesviridae is a large family of double-stranded DNA(dsDNA)viruses that cause a variety of human diseases ranging from cold sores and chicken pox to congenital defects,blindness and cancer(Chayavichitsil...Dear Editor,Herpesviridae is a large family of double-stranded DNA(dsDNA)viruses that cause a variety of human diseases ranging from cold sores and chicken pox to congenital defects,blindness and cancer(Chayavichitsilp et al.,2009;Wang et al.,2018).In the past 70 years,substantial advances in our knowledge of the molecular biology of herpesviruses have led to insights into disease pathogenesis and management.However,the mechanism for capsid assembly that requires the ordered packing of about 4,000 protein subunits into the hexons,pentons and triplexes remains elusive.It is still a puzzle how initially identical subunits adopt both hexameric and pentameric conformations in the capsid and select the correct locations needed to form closed shells of the proper size.Biochemical and genetic studies have shown that the portal is involved in initiation of capsid assembly(Newcomb et al.,2005)and functions akin to a DNA-sensor coupling genome-packaging achieved by a genome-packaging machinery-“terminase complex”(Chen et al.,2020;Yunxiang Yang,2020)with icosahedral capsid maturation(Lokareddy et al.,2017).Structural investigations of the herpesvirus portal have proven challenging due to the small size of this dodecamer,which accounts for less than 1%of the total mass of the capsid protein layer and the technical difficulties involved in resolving non-icosahedral components of such large icosahedral viruses(diameter is∼1,250Å).Efforts of many investigators over two decades have made to reconstruct the cryo-electron microscopy(cryo-EM)structure of herpesvirus portal vertex and more recently near-atomic structures of two herpesvirus(herpes simplex virus type 1(HSV-1)and Kaposi’s sarcoma-associated herpesvirus(KSHV))portal vertices were reported(McElwee et al.,2018;Gong et al.,2019;Liu et al.,2019).展开更多
Herein,we propose an experimentally feasible scheme to show the quantum phase transition of the Jaynes-Cummings(JC)model by modulating the transition frequency of a two-level system in a quantum Rabi model with strong...Herein,we propose an experimentally feasible scheme to show the quantum phase transition of the Jaynes-Cummings(JC)model by modulating the transition frequency of a two-level system in a quantum Rabi model with strong coupling.By tuning the modulation frequency and amplitude,the ratio of the effective coupling strength of the rotating terms to the effective cavity(atomic transition)frequency can enter the deep-strong coupling regime,while the counter-rotating terms can be neglected.Thus,a deep-strong JC model is obtained.The ratio of the coupling strength to resonance frequencies in the deep-strong JC model is two orders of magnitude larger than the corresponding ratio in the original quantum Rabi model.Our scheme can be employed in atom-cavity resonance and off-resonance cases,and it is valid over a broad range.The nonzero average cavity photons of the ground state indicate the emergence of a quantum phase transition.Further,we demonstrate the dependence of the phase diagram on the atom-cavity detuning and modulation parameters.All the parameters used in our scheme are within the reach of current experimental technology.Our scheme provides a new mechanism for investigating the critical phenomena of finite-sized systems without requiring classical field limits,thereby opening a door for studying fundamental quantum phenomena occurring in the ultrastrong and even deep-strong coupling regimes.展开更多
Varicella-zoster is a highly communicable virus that can be transmitted through the airborne route.About one quarter of people are infected with this virus.Previous studies have described the structure of A-capsid and...Varicella-zoster is a highly communicable virus that can be transmitted through the airborne route.About one quarter of people are infected with this virus.Previous studies have described the structure of A-capsid and a blurred reconstruction of the C-capsid with icosahedral symmetry.In this study,we have determined the more precise detailed structures of the varicella-zoster virus(VZV)B-and C-capsid in icosahedral symmetry using a combination of block-based reconstruction and symmetry relaxation strategies.In addition,we are reporting structural details of the portal vertex reconstructions in five-fold symmetry and portal reconstructions in twelve-fold symmetry.The structures unveil the basis for the high thermal stability of the VZV capsid.The conformational flexibility of structural elements of the capsid plays a role in the assembly of the capsid and drives processes critical for the viral life cycle.The results of the study open up new avenues for the development of drugs against a highly prevalent and contagious pathogen.展开更多
Enterovirus A71(EV-A71) causes major outbreaks of hand,foot,and mouth disease(HFMD) in many countries,most frequently affecting children,and a small proportion of cases may lead to death.Currently,no vaccine is availa...Enterovirus A71(EV-A71) causes major outbreaks of hand,foot,and mouth disease(HFMD) in many countries,most frequently affecting children,and a small proportion of cases may lead to death.Currently,no vaccine is available in most endemic regions,and no licenced treatments for EV-A71 infection are available.Here,we characterize a human monoclonal antibody(Hu MAb),E1,by screening a Fab antibody phage library derived from patients who recovered from EV-A71 infection.E1 exhibits strong neutralizing activity against EV-A71 virus in cells.The cryo-electron microscopy(cryo-EM) structures of the EV-A71 virion in complex with E1 Fab fragments demonstrated that E1 recognized an epitope formed by residues in the BC and HI loops of VP1.In a mouse model,E1 effectively protected against lethal EV-A71 challenge in both prophylactic and therapeutic treatment.In particular,E1 significantly reduces virus titers and muscle damage.E1 might represent a potential adjunct to EV-A71 treatment.展开更多
Dear Editor,Tailed,double-stranded DNA(dsDNA)bacteriophages,which belong to the order of Caudovirales,have a tail attached to a pentameric vertex of the icosahedral capsid shell(head)through a 12-fold portal(Johnson a...Dear Editor,Tailed,double-stranded DNA(dsDNA)bacteriophages,which belong to the order of Caudovirales,have a tail attached to a pentameric vertex of the icosahedral capsid shell(head)through a 12-fold portal(Johnson and Chiu,2007).The phages package genomic dsDNA into a round procapsid using the portal in complex with an ATP-dependent terminase complex as the motor.During packaging,the procapsid shell expands to a more angular intermediate to match the size of the viral genome(Guo et al.,2014).When the phage head is full,the portal detects internal pressure and conveys a signal from the inner capsid to the exterior,which triggers a sequence of events-the terminase complex cleaving mature DNA genome from a multi-genome concatemer,the release of the terminase complex from the portal,and the attachment of the tail complex-in the completion of phage assembly(Lander et al.,2006;Johnson and Chiu,2007).At the beginning of phage infection,the tail is responsible for receptor recognition,and the portal and tail act as a tunnel for DNA delivery into the host cytoplasm(Johnson and Chiu,2007).These mechanisms of DNA packaging and ejection may also be conserved in many other DNA viruses,including herpesvirus(Wang et al.,2020;Yang et al.,2020).展开更多
A lithium-sulfur(Li-S)system is an important candidate for future lithium-ion system due to its low cost and high specific theoretical capacity(1675 m Ah/g,2600 Wh/kg),which is greatly hindered by the poor conductivit...A lithium-sulfur(Li-S)system is an important candidate for future lithium-ion system due to its low cost and high specific theoretical capacity(1675 m Ah/g,2600 Wh/kg),which is greatly hindered by the poor conductivity of sulfur,large volume change and dissolution of lithium polysulfides.Two-dimensional(2D)materials with monolayers or few-layers usually have peculiar structures and physical/chemical properties,which can resolve the critical issues in Li-S batteries.Especially,the metal-based 2D nanomaterials,including ferrum,cobalt or other metal-based composites with various anions,can provide high conductivity,large surface area and abundant reaction sites for restraining the diffusion for lithium polysulfides.In this mini-review,we will present an overview of recent developments on metal-based 2D nanomaterials with various anions as the electrode materials for Li-S batteries.Since the main bottleneck for the Li-S system is the shuttle of polysulfides,emphasis is placed on the structure and components,physical/chemical interaction and interaction mechanisms of the 2D materials.Finally,the challenges and prospects of metal-based 2D nanomaterials for Li-S batteries are discussed and proposed.展开更多
The transport properties of core–shell nanowires(CSNWs)under interface modulation and confinement are investigated based on the atomic-bond-relaxation(ABR)correlation mechanism and Fermi’s golden rule.An analytical ...The transport properties of core–shell nanowires(CSNWs)under interface modulation and confinement are investigated based on the atomic-bond-relaxation(ABR)correlation mechanism and Fermi’s golden rule.An analytical expression for the relationship between carrier mobility and interface mismatch strain is derived and the influence of size,shell thickness and alloyed layer on effective mass,band structures,and deformation potential constant are studied.It is found that interface modulation can not only reduce the lattice mismatch to optimize the band alignment,but also participate in the carrier transport for enhancing mobility.Moreover,the underlying mechanism regarding the interface shape dependence of transport properties in CSNWs is clarified.The great enhancement of electron mobility suggests that the interface modulation may become a potential pathway to improving the performance of nanoelectronic devices.展开更多
The Einstein–Podolsky–Rosen(EPR)paradox is one of the milestones in quantum foundations,arising from the lack of a local realistic description of quantum mechanics.The EPR paradox has stimulated an important concept...The Einstein–Podolsky–Rosen(EPR)paradox is one of the milestones in quantum foundations,arising from the lack of a local realistic description of quantum mechanics.The EPR paradox has stimulated an important concept of“quantum nonlocality,”which manifests itself in three types:quantum entanglement,quantum steering,and Bell’s nonlocality.Although Bell’s nonlocality is more often used to show“quantum nonlocality,”the original EPR paradox is essentially a steering paradox.In this work,we formulate the original EPR steering paradox into a contradiction equality,thus making it amenable to experimental verification.We perform an experimental test of the steering paradox in a two-qubit scenario.Furthermore,by starting from the steering paradox,we generate a generalized linear steering inequality and transform this inequality into a mathematically equivalent form,which is friendlier for experimental implementation,i.e.,one may measure the observables only in the x,y,or z axis of the Bloch sphere,rather than other arbitrary directions.We also perform experiments to demonstrate this scheme.Within the experimental errors,the experimental results coincide with theoretical predictions.Our results deepen the understanding of quantum foundations and provide an efficient way to detect the steerability of quantum states.展开更多
Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and superionicity.However,the electronic origin of t...Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and superionicity.However,the electronic origin of these unusual behaviors remains elusive.In this study,we demonstrate that the high-lying occupied 3d orbital of Cu causes a strong s-d coupling with its unoccupied 4s state when local symmetry is reduced.This leads to strong phonon anharmonicity and is responsible for these intriguing properties.For example,during thermal transport,symmetry-controlled s-d coupling can substantially lower the lattice potential barrier,thereby enhancing the anharmonicity and scattering between phonons and ultimately significantly reducing lattice thermal conductivity.We confirmed this understanding with Raman spectra measurements,which demonstrated a remarkable red shift in the phonon vibrational frequency with an increase in the temperature of Cu-based semiconductors.Our study shows that the cause of phonon anharmonicity is related to the fundamental electronic structures,which can also explain other unusual physical properties of the Cu compounds.展开更多
Multi-photon bundle states are crucial for a broad range of applications such as quantum metrology,quantum lithography,quantum communication,and quantum biology.Here we propose a scheme that generates multi-photon bun...Multi-photon bundle states are crucial for a broad range of applications such as quantum metrology,quantum lithography,quantum communication,and quantum biology.Here we propose a scheme that generates multi-photon bundles via virtual excitations in a quantum Rabi model.Our approach utilizes a Ξ-type three-level atom,where the upper two levels are coupled to a cavity field to form a quantum Rabi model with ultrastrong coupling,and the transition between the lower two levels is driven by two sequences of Gaussian pulses.We show that the driving pulses induce deterministic emission of multiple photons from the eigenstates of the quantum Rabi model via the stimulated Raman adiabatic passage technique,and hence can create bundles of multiple photons on-demand in the cavity output field.We calculate the generalized second-order correlation functions of the output photons,which reveal that the emitted photons form antibunched multi-photon bundles.展开更多
We adopt the quark pair creation model to investigate the light meson emissions of several charmoniumlike states.The quark pair creation model is applied to four-body systems,and we calculate the pion/kaon emissions o...We adopt the quark pair creation model to investigate the light meson emissions of several charmoniumlike states.The quark pair creation model is applied to four-body systems,and we calculate the pion/kaon emissions of X(4700),Z_(c)(4430),Y(4230),Y(4360),Y(4390),and Y(4660)within compact tetraquark configurations.We find that the pion/kaon decay widths of X(4700)and Z_(c)(4430)the resonances Y(4230),Y(4360),Y(4390),and Y(4660)cay behaviors will provide useful information for future experimental searches and theoretical interpretations.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11975095,12075082,11935006,and 12247105)the Major Sci-Tech Program of Hunan Province,China(Grant No.2023ZJ1010)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2019A1515011400 and 2023A151501223).
文摘We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574080 and 91833302)。
文摘We investigate the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons(APNRs) containing atomic vacancies with different distributions and concentrations using ab initio density functional calculations. It is found that the atomic vacancies are easier to form and detain at the edge region rather than a random distribution through analyzing formation energy and diffusion barrier. The highly local defect states are generated at the vicinity of the Fermi level, and emerge a deep-to-shallow transformation as the width increases after introducing vacancies in APNRs.Moreover, the electrical transport of APNRs with vacancies is enhanced compared to that of the perfect counterparts. Our results provide a theoretical guidance for the further research and applications of PNRs through defect engineering.
基金the National Natural Science Foundation of China(Grant Nos.11935006,12075082,12205088,and 11975095)the Science and Technology Innovation Program of Hunan Province,China(Grant No.2020RC4047)+1 种基金the Scientific Research Fund of the Hunan Provincial Education Department(Grant No.21B0639)Hunan Normal University Open Foundation of Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of the Ministry of Education(Grant No.QSQC2009).
文摘We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum channels of guided photons.The perfect mirror imposed by the finite end exerts a retarded feedback mechanism to allow for information backflow,which leads to NM dynamics.For the energy separation of the atom far away from the cutoff frequencies of transverse modes,the delay differential equations are obtained with single-excitation initial in the atom.Our attention is focused on the effects of multiple quantum channels involved in guiding photons on the degree of nonMarkovian behavior.An asymptotic value of the non-Markovianity N_(1)can be found as the atom–mirror distance is large enough,however,the asymptotic value of N_(2)of the atom interacting with the effective double-modes is lower than that of the atom interacting with the effective single-mode.We also show that N_(1)is a constant,and the analytical expression for N_(2)is related to the parameters associated with the modes,which is related to the interference of the two modes.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12274455,11774421,21622304,61674045,11604063,and 12074116)the National Key R&D Program of China(Grant Nos.2016YFA0200700 and 2022YFA1403800)+1 种基金the Strategic Priority Research Program(Chinese Academy of Sciences,CAS)(Grant No.XDB30000000)supported by the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(Grant No.21XNLG27)。
文摘Layered transition metal dichalcogenides(TMDCs)gained widespread attention because of their electron-correlationrelated physics,such as charge density wave(CDW),superconductivity,etc.In this paper,we report the high-resolution angle-resolved photoemission spectroscopy(ARPES)studies on the electronic structure of Ti-doped 1T-Ti_(x)Ta_(1-x)S_(2) with different doping levels.We observe a flat band that originates from the formation of the star of David super-cell at the x=5%sample at the low temperature.With the increasing Ti doping levels,the flat band vanishes in the x=8%sample due to the extra hole carrier.We also find the band shift and variation of the CDW gap caused by the Ti-doping.Meanwhile,the band folding positions and the CDW vector g_(CDW)intact.Our ARPES results suggest that the localized flat band and the correlation effect in the 1T-TMDCs could be tuned by changing the filling factor through the doping electron or hole carriers.The Ti-doped 1T-Ti_(x)Ta_(1-x)S_(2) provides a platform to fine-tune the electronic structure evolution and a new insight into the strongly correlated physics in the TMDC materials.
基金the National Natural Science Foundation of China(Grant No.91833302).
文摘Understanding the physical mechanism of structural stability and transition in various polytypes of layered transition metal dichalcogenides under the external stimulus is of crucial importance for their new applications.Here,we investigate the thickness-dependent structural properties of MoS2 under the condition of hydrostatic pressure in terms of bond relaxation and thermodynamics considerations.For both types of MoS2 structures,we find that the transition and metallization are significantly modulated by hydrostatic pressure and the number of layers.We establish a pressure-size phase diagram to address the transition mechanism.Our study not only provides insights into the thickness-dependent structural properties of MoS2,but also shows a theoretical guidance for the design and fabrication of MoS2-based devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11975095,12075082,and 11935006)the Science and Technology Innovation Program of Hunan Province,China(Grant No.2020RC4047)。
文摘We investigate few-photon scattering properties in two one-dimensional waveguides chirally coupled to a nonlinear cavity.The quantum states of scattered few photons are solved analytically via a real-space approach,and the solution indicates the few-photon reflection and transmission properties.When inputting two photons of equal energy to resonate with the cavity,the propagation characteristics of the two photons will be interesting,which is different from the previous anti-bunching effects with a quantum emitter.More importantly,when the total energy of the two incident photons equals the energy of a nonlinear cavity accommodating two photons,influence of the bound state will become larger to result in disappearance of antibunching effect.However,the bound state has no effect on probability of routing to another waveguide.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11975095,12075082,and 11935006)the Science and Technology Innovation Program of Hunan Province,China(Grant No.2020RC4047)the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering.
文摘We investigate the entanglement dynamics of two distinguishable two-level systems(TLSs)characterized by energy differenceδlocated inside a rectangular hollow metallic waveguide of transverse dimensions a and b.The effects of energy differenceδand the inter-TLS distance on the time evolution of the concurrence of the TLSs are examined in the single excitation subspace when the energy separation of the TLS is far away from the cutoff frequencies of the transverse mode.
基金mainly funded by National Science Foundation of China(Nos.12074116 and 52172197)the Youth 1000 Talent Program of China,Undergraduate Scientific Research Innovation Project of China(No.202110542037)+3 种基金Science and Technology Innovation Platform(No.2019RS1032)Major Program of Natural Science Foundation of Hunan Province of Hunan Province,and Hunan Normal University(Nos.2021133,21CSZ004 and 21CSZ029)the support from Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy(No.2020CB1007)the support from Science and Technology Innovation Program of Hunan Province(No.2021RC2075)。
文摘Transition metal hydroxides/oxyhydroxides have recently emerged as highly active electrocatalysts for oxygen evolution reaction in alkaline water electrolysis,while have not yet been widely investigated for hydrogen evolution electrocatalysts owing to their unfavorable H*-adsorption,making it difficult to construct an overall-water-splitting cell for hydrogen production.In this work,we proposed a straightforward and effective approach to develop an efficient in-plane heterostructured CoOOH/Co(OH)_(2) catalyst via in-situ electrochemical dehydrogenation method,in which the dehydrogenated–CoOOH and Co(OH)_(2) at the surface synergistically boost the hydrogen evolution reaction(HER)kinetics in base as confirmed by high-resolution transmission electron microscope,synchrotron X-ray absorption spectroscopy,and electron energy loss spectroscopy.Due to the in-situ dehydrogenation of ultrathin Co(OH)_(2) nanosheets,the catalytic activity of the CoOOH/Co(OH)_(2) heterostructures is progressively improved,which exhibit outstanding hydrogen-evolving activity in base requiring a low overpotential of 132 m V to afford 10 m A/cm^(2)with very fast reaction kinetics after 60 h dehydrogenation.The gradually improved catalytic performance for the CoOOH/Co(OH)2is probably due to the enhanced H*-adsorption induced by the synergistic effect of heterostructures and better conductivity of Co OOH relative to electrically insulating Co(OH)_(2).This work will open the opportunity for a new family of transition metal hydroxides/oxyhydroxides as active HER catalysts,and also highlight the importance of using in situ techniques to construct precious metal-free efficient catalysts for alkaline hydrogen evolution.
文摘Halide perovskites(ABX_(3)), as promising candidates for solar cell photovoltaic devices, have recently attracted increasing research interest [1-3], but many issues remain unsolved for their practical applications. One such issue is their poor stability, which largely reduces device lifetime and efficiency [4]. In recent decades, using inorganic ions or organic molecules for replacement or alloying the A-site atoms in halide perovskites has improved thermodynamic stability to some extent.
基金Work was supported by the Key Programs of the Chinese Academy(KJZD-SW-L05)the Strategic Priority Research Program(XDB29010000)+2 种基金National Key Research and Development Program(2018YFA0900801 and 2017YFC0840300)National Natural Science Foundation of China(31800145 and 81520108019)and National Science Foundation of Hunan Province,China(2019JJ10002)Ling Zhu was sponsored by the Youth Innovation Promotion Association at the Chinese Academy of Science.Xiangxi Wang was supported by Ten Thousand Talent Program and the NSFS Innovative Research Group(No.81921005)。
文摘Dear Editor,Herpesviridae is a large family of double-stranded DNA(dsDNA)viruses that cause a variety of human diseases ranging from cold sores and chicken pox to congenital defects,blindness and cancer(Chayavichitsilp et al.,2009;Wang et al.,2018).In the past 70 years,substantial advances in our knowledge of the molecular biology of herpesviruses have led to insights into disease pathogenesis and management.However,the mechanism for capsid assembly that requires the ordered packing of about 4,000 protein subunits into the hexons,pentons and triplexes remains elusive.It is still a puzzle how initially identical subunits adopt both hexameric and pentameric conformations in the capsid and select the correct locations needed to form closed shells of the proper size.Biochemical and genetic studies have shown that the portal is involved in initiation of capsid assembly(Newcomb et al.,2005)and functions akin to a DNA-sensor coupling genome-packaging achieved by a genome-packaging machinery-“terminase complex”(Chen et al.,2020;Yunxiang Yang,2020)with icosahedral capsid maturation(Lokareddy et al.,2017).Structural investigations of the herpesvirus portal have proven challenging due to the small size of this dodecamer,which accounts for less than 1%of the total mass of the capsid protein layer and the technical difficulties involved in resolving non-icosahedral components of such large icosahedral viruses(diameter is∼1,250Å).Efforts of many investigators over two decades have made to reconstruct the cryo-electron microscopy(cryo-EM)structure of herpesvirus portal vertex and more recently near-atomic structures of two herpesvirus(herpes simplex virus type 1(HSV-1)and Kaposi’s sarcoma-associated herpesvirus(KSHV))portal vertices were reported(McElwee et al.,2018;Gong et al.,2019;Liu et al.,2019).
基金supported by the National Natural Science Foundation of China(Grant No.12075083)。
文摘Herein,we propose an experimentally feasible scheme to show the quantum phase transition of the Jaynes-Cummings(JC)model by modulating the transition frequency of a two-level system in a quantum Rabi model with strong coupling.By tuning the modulation frequency and amplitude,the ratio of the effective coupling strength of the rotating terms to the effective cavity(atomic transition)frequency can enter the deep-strong coupling regime,while the counter-rotating terms can be neglected.Thus,a deep-strong JC model is obtained.The ratio of the coupling strength to resonance frequencies in the deep-strong JC model is two orders of magnitude larger than the corresponding ratio in the original quantum Rabi model.Our scheme can be employed in atom-cavity resonance and off-resonance cases,and it is valid over a broad range.The nonzero average cavity photons of the ground state indicate the emergence of a quantum phase transition.Further,we demonstrate the dependence of the phase diagram on the atom-cavity detuning and modulation parameters.All the parameters used in our scheme are within the reach of current experimental technology.Our scheme provides a new mechanism for investigating the critical phenomena of finite-sized systems without requiring classical field limits,thereby opening a door for studying fundamental quantum phenomena occurring in the ultrastrong and even deep-strong coupling regimes.
基金supported by the Strategic Priority Research Program (XDB29010000)National Key Research and Development Program (2018YFA0900801)+5 种基金National Science Foundation Grants 32200135 and 12034006supported by National Science Fund for Distinguished Young Scholar (No.32325004)the NSFS Innovative Research Group (No.81921005)supported by the Young Elite Scientists Sponsorship Program by CAST (2022QNRC001)the Youth Innovation Promotion Association of CAS grantsupported by the Special Research Assistant Project of the Chinese Academy of Sciences.
文摘Varicella-zoster is a highly communicable virus that can be transmitted through the airborne route.About one quarter of people are infected with this virus.Previous studies have described the structure of A-capsid and a blurred reconstruction of the C-capsid with icosahedral symmetry.In this study,we have determined the more precise detailed structures of the varicella-zoster virus(VZV)B-and C-capsid in icosahedral symmetry using a combination of block-based reconstruction and symmetry relaxation strategies.In addition,we are reporting structural details of the portal vertex reconstructions in five-fold symmetry and portal reconstructions in twelve-fold symmetry.The structures unveil the basis for the high thermal stability of the VZV capsid.The conformational flexibility of structural elements of the capsid plays a role in the assembly of the capsid and drives processes critical for the viral life cycle.The results of the study open up new avenues for the development of drugs against a highly prevalent and contagious pathogen.
基金supported by the CAMS Innovation Fund for Medical Sciences(CIFMS)(2016-I2M-1-014)the National Natural Science Foundation of China(31500757 and 12034006)。
文摘Enterovirus A71(EV-A71) causes major outbreaks of hand,foot,and mouth disease(HFMD) in many countries,most frequently affecting children,and a small proportion of cases may lead to death.Currently,no vaccine is available in most endemic regions,and no licenced treatments for EV-A71 infection are available.Here,we characterize a human monoclonal antibody(Hu MAb),E1,by screening a Fab antibody phage library derived from patients who recovered from EV-A71 infection.E1 exhibits strong neutralizing activity against EV-A71 virus in cells.The cryo-electron microscopy(cryo-EM) structures of the EV-A71 virion in complex with E1 Fab fragments demonstrated that E1 recognized an epitope formed by residues in the BC and HI loops of VP1.In a mouse model,E1 effectively protected against lethal EV-A71 challenge in both prophylactic and therapeutic treatment.In particular,E1 significantly reduces virus titers and muscle damage.E1 might represent a potential adjunct to EV-A71 treatment.
基金This research was supported by the National Research and Development Program of China(2016YFA0501103)and the National Natural Science Foundation of China(31971122 and 31570742)National Science Foundation of Hunan Province,China(2019JJ10002 and 2019JJ40096)the Research Foundation of Education Bureau of Hunan province,China(19B372).
文摘Dear Editor,Tailed,double-stranded DNA(dsDNA)bacteriophages,which belong to the order of Caudovirales,have a tail attached to a pentameric vertex of the icosahedral capsid shell(head)through a 12-fold portal(Johnson and Chiu,2007).The phages package genomic dsDNA into a round procapsid using the portal in complex with an ATP-dependent terminase complex as the motor.During packaging,the procapsid shell expands to a more angular intermediate to match the size of the viral genome(Guo et al.,2014).When the phage head is full,the portal detects internal pressure and conveys a signal from the inner capsid to the exterior,which triggers a sequence of events-the terminase complex cleaving mature DNA genome from a multi-genome concatemer,the release of the terminase complex from the portal,and the attachment of the tail complex-in the completion of phage assembly(Lander et al.,2006;Johnson and Chiu,2007).At the beginning of phage infection,the tail is responsible for receptor recognition,and the portal and tail act as a tunnel for DNA delivery into the host cytoplasm(Johnson and Chiu,2007).These mechanisms of DNA packaging and ejection may also be conserved in many other DNA viruses,including herpesvirus(Wang et al.,2020;Yang et al.,2020).
基金supported by National Natural Science Foundation of China(No.52172197)the Joint Funds of the National Natural Science Foundation of China(No.U1865207)+5 种基金Science and Technology Innovation Platform(No.2018RS3070)Hundred Youth Talents Programs of Hunan ProvincePhD Start-up Foundation of Hengyang Normal University(No.19QD10)Scientific Research Fund of Hunan Provincial Education Department(No.20A062)the support from Hunan joint international laboratory of advanced materials and technology for clean energy(No.2020CB1007)the Science and Technology Innovation Program of Hunan Province(No.2016TP1020)。
文摘A lithium-sulfur(Li-S)system is an important candidate for future lithium-ion system due to its low cost and high specific theoretical capacity(1675 m Ah/g,2600 Wh/kg),which is greatly hindered by the poor conductivity of sulfur,large volume change and dissolution of lithium polysulfides.Two-dimensional(2D)materials with monolayers or few-layers usually have peculiar structures and physical/chemical properties,which can resolve the critical issues in Li-S batteries.Especially,the metal-based 2D nanomaterials,including ferrum,cobalt or other metal-based composites with various anions,can provide high conductivity,large surface area and abundant reaction sites for restraining the diffusion for lithium polysulfides.In this mini-review,we will present an overview of recent developments on metal-based 2D nanomaterials with various anions as the electrode materials for Li-S batteries.Since the main bottleneck for the Li-S system is the shuttle of polysulfides,emphasis is placed on the structure and components,physical/chemical interaction and interaction mechanisms of the 2D materials.Finally,the challenges and prospects of metal-based 2D nanomaterials for Li-S batteries are discussed and proposed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91833302 and U2001215)the Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2022A1515010989)the Special Project in Key Fields of Guandong Universities,China(Grant No.2022ZDZX3015)。
文摘The transport properties of core–shell nanowires(CSNWs)under interface modulation and confinement are investigated based on the atomic-bond-relaxation(ABR)correlation mechanism and Fermi’s golden rule.An analytical expression for the relationship between carrier mobility and interface mismatch strain is derived and the influence of size,shell thickness and alloyed layer on effective mass,band structures,and deformation potential constant are studied.It is found that interface modulation can not only reduce the lattice mismatch to optimize the band alignment,but also participate in the carrier transport for enhancing mobility.Moreover,the underlying mechanism regarding the interface shape dependence of transport properties in CSNWs is clarified.The great enhancement of electron mobility suggests that the interface modulation may become a potential pathway to improving the performance of nanoelectronic devices.
基金National Key Research and Development Program of China(2017YFA0305200,2016YFA0301300)National Natural Science Foundation of China(11875167,12075001,12075245,61974168)+1 种基金Key R&D Program of Guangdong Province(2018B030325001,2018B030329001)Xiaoxiang Scholars Programme of Hunan Normal University.
文摘The Einstein–Podolsky–Rosen(EPR)paradox is one of the milestones in quantum foundations,arising from the lack of a local realistic description of quantum mechanics.The EPR paradox has stimulated an important concept of“quantum nonlocality,”which manifests itself in three types:quantum entanglement,quantum steering,and Bell’s nonlocality.Although Bell’s nonlocality is more often used to show“quantum nonlocality,”the original EPR paradox is essentially a steering paradox.In this work,we formulate the original EPR steering paradox into a contradiction equality,thus making it amenable to experimental verification.We perform an experimental test of the steering paradox in a two-qubit scenario.Furthermore,by starting from the steering paradox,we generate a generalized linear steering inequality and transform this inequality into a mathematically equivalent form,which is friendlier for experimental implementation,i.e.,one may measure the observables only in the x,y,or z axis of the Bloch sphere,rather than other arbitrary directions.We also perform experiments to demonstrate this scheme.Within the experimental errors,the experimental results coincide with theoretical predictions.Our results deepen the understanding of quantum foundations and provide an efficient way to detect the steerability of quantum states.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174099,61922077,11874347,12088101,11991060U2230402)+3 种基金the National Key Research and Development Program of China(Grant Nos.2018YFB2200100,and 2020YFB1506400)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB22)the Beijing Science and Technology Committee(Grant No.Z181100005118003)supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.Y2021042)。
文摘Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and superionicity.However,the electronic origin of these unusual behaviors remains elusive.In this study,we demonstrate that the high-lying occupied 3d orbital of Cu causes a strong s-d coupling with its unoccupied 4s state when local symmetry is reduced.This leads to strong phonon anharmonicity and is responsible for these intriguing properties.For example,during thermal transport,symmetry-controlled s-d coupling can substantially lower the lattice potential barrier,thereby enhancing the anharmonicity and scattering between phonons and ultimately significantly reducing lattice thermal conductivity.We confirmed this understanding with Raman spectra measurements,which demonstrated a remarkable red shift in the phonon vibrational frequency with an increase in the temperature of Cu-based semiconductors.Our study shows that the cause of phonon anharmonicity is related to the fundamental electronic structures,which can also explain other unusual physical properties of the Cu compounds.
基金supported by the National Natural Science Foundation of China (Grant No. 12075083)the Natural Science Foundation of Hunan Province,China (Grant No. 2020JJ5345)+1 种基金supported by the National Science Foundation (Grant Nos. 2006076, and 2037987)UC-MRPI Program (Grant No. ID M23PL5936)。
文摘Multi-photon bundle states are crucial for a broad range of applications such as quantum metrology,quantum lithography,quantum communication,and quantum biology.Here we propose a scheme that generates multi-photon bundles via virtual excitations in a quantum Rabi model.Our approach utilizes a Ξ-type three-level atom,where the upper two levels are coupled to a cavity field to form a quantum Rabi model with ultrastrong coupling,and the transition between the lower two levels is driven by two sequences of Gaussian pulses.We show that the driving pulses induce deterministic emission of multiple photons from the eigenstates of the quantum Rabi model via the stimulated Raman adiabatic passage technique,and hence can create bundles of multiple photons on-demand in the cavity output field.We calculate the generalized second-order correlation functions of the output photons,which reveal that the emitted photons form antibunched multi-photon bundles.
基金Supported by the National Natural Science Foundation of China(11705056,12175037,11947224,11475192,11975245,U1832173)the Key Project of Hunan Provincial Education Department under(21A0039)+3 种基金the State Scholarship Fund of China Scholarship Council(22006725011)the Sino-German CRC 110“Symmetries and the Emergence of Structure in QCD”project by NSFC(12070131001)the Key Research Program of Frontier Sciences,CAS(Y7292610K1)the National Key Research and Development Program of China(2020YFA0406300)。
文摘We adopt the quark pair creation model to investigate the light meson emissions of several charmoniumlike states.The quark pair creation model is applied to four-body systems,and we calculate the pion/kaon emissions of X(4700),Z_(c)(4430),Y(4230),Y(4360),Y(4390),and Y(4660)within compact tetraquark configurations.We find that the pion/kaon decay widths of X(4700)and Z_(c)(4430)the resonances Y(4230),Y(4360),Y(4390),and Y(4660)cay behaviors will provide useful information for future experimental searches and theoretical interpretations.