Establishing the structure-property relationship in amorphous materials has been a long-term grand challenge due to the lack of a unified description of the degree of disorder.In this work,we develop SPRamNet,a neural...Establishing the structure-property relationship in amorphous materials has been a long-term grand challenge due to the lack of a unified description of the degree of disorder.In this work,we develop SPRamNet,a neural network based machine-learning pipeline that effectively predicts structure-property relationship of amorphous material via global descriptors.Applying SPRamNet on the recently discovered amorphous monolayer carbon,we successfully predict the thermal and electronic properties.More importantly,we reveal that a short range of pair correlation function can readily encode sufficiently rich information of the structure of amorphous material.Utilizing powerful machine learning architectures,the encoded information can be decoded to reconstruct macroscopic properties involving many-body and long-range interactions.Establishing this hidden relationship offers a unified description of the degree of disorder and eliminates the heavy burden of measuring atomic structure,opening a new avenue in studying amorphous materials.展开更多
The transition of cobalt ions located at tetrahedral sites will produce strong absorption in the visible and nearinfrared regions,and is expected to work in a passively Q-switched solid-state laser at the eye-safe wav...The transition of cobalt ions located at tetrahedral sites will produce strong absorption in the visible and nearinfrared regions,and is expected to work in a passively Q-switched solid-state laser at the eye-safe wavelength of 1.5μm.In this study,Co^(2+)ions were introduced into the wide bandgap semiconductor material ZnGa_(2)O_(4),and large-sized and high-quality Co^(2+)-doped ZnGa_(2)O_(4)crystals with a volume of about 20 cm^(3)were grown using the vertical gradient freeze(VGF)method.Crystal structure and optical properties were analyzed using X-ray powder diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and absorption spectroscopy.XRD results show that the Co^(2+)-doped ZnGa_(2)O_(4)crystal has a pure spinel phase without impurity phases and the rocking curve full width at half maximum(FWHM)is only 58 arcsec.The concentration of Co^(2+)in Co^(2+)-doped ZnGa_(2)O_(4)crystals was determined to be 0.2 at.%by the energy dispersive X-ray spectroscopy.The optical band gap of Co^(2+)-doped ZnGa_(2)O_(4)crystals is 4.44 eV.The optical absorption spectrum for Co^(2+)-doped ZnGa_(2)O_(4)reveals a prominent visible absorption band within 550−670 nm and a wide absorption band spanning from 1100 to 1700 nm.This suggests that the Co^(2+)ions have substituted the Zn^(2+)ions,which are typically tetrahedrally coordinated,within the lattice structure of ZnGa_(2)O_(4).The visible region's absorption peak and the near-infrared broad absorption band are ascribed to the^(4)A_(2)(4F)→^(4)T_(1)(4P)and 4A2(4F)→^(4)T_(1)(4F)transitions,respectively.The optimal ground state absorption cross section was determined to be 3.07×10^(−19)cm^(2)in ZnGa_(2)O_(4),a value that is comparatively large within the context of similar materials.This finding suggests that ZnGa_(2)O_(4)is a promising candidate for use in near-infrared passive Q-switched solid-state lasers.展开更多
Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a crit...Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a critical role during poling fabrication.To enhance the imaging detection efficiency of the domain structure in z-cut PPLN,we have developed a second-harmonic generation microscope system specifically designed to produce a longitudinal electric field in foci for the imaging domain inversion.We demonstrated that imaging using a longitudinal electric field can achieve a contrast ratio enhancement by a factor of 1.77,showing high imaging efficiency and making the proposed method suitable for in situ monitoring of the z-cut PPLN poling process.展开更多
Multiphoton entanglement with high information capacity plays an essential role in quantum information processing.The appearance of parallel beam splitting(BS)in a gradient metasurface provides the chance to prepare t...Multiphoton entanglement with high information capacity plays an essential role in quantum information processing.The appearance of parallel beam splitting(BS)in a gradient metasurface provides the chance to prepare the multiphoton entanglement in one step.Here,we use a single metasurface to construct multiphoton path-polarization entanglement.Based on the parallel BS property,entanglement among N unentangled photons is created after they pass through a gradient metasurface.Also,with this ability,entanglement fusion among several pairs of entangled photons is set up,which can greatly enlarge the entanglement dimension.These theoretical results pave the way for manipulating metasurface-based multiphoton entanglement,which holds great promise for ultracompact on-chip quantum information processing.展开更多
Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus o...Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus on one unique quantum phase induced by the electron-hole interaction in two-dimensional systems,known as“exciton insulators”(EIs).Although this phase of matter has been studied for more than half a century,suitable platforms for its stable realization remain scarce.We provide an overview of the strategies to realize EIs in accessible materials and structures,along with a discussion on some unique properties of EIs stemming from the band structures of these materials.Additionally,signatures in experiments to distinguish EIs are discussed.展开更多
Based on numerical solutions of the time-dependent Schr ¨odinger equation, we theoretically investigate the photoelectron spectrum of hydrogen atoms ionized by a pair of ultrashort, intense, and orthogonally pola...Based on numerical solutions of the time-dependent Schr ¨odinger equation, we theoretically investigate the photoelectron spectrum of hydrogen atoms ionized by a pair of ultrashort, intense, and orthogonally polarized laser pulses with a relative time delay in a pump–probe configuration. The pump pulse resonantly excites electrons from the 1s and 2p levels,inducing Rabi oscillations. The resulting dynamically enhanced Autler–Townes(AT) splitting is observed in the photoelectron energy spectrum upon interaction with the second probe pulse. In contrast to the previous parallel-polarization scheme, the proposed orthogonal-polarization configuration enables the resolution of dynamically enhanced AT splitting over a considerably wider range of probe photon energies.展开更多
Plasmonic modes within metal nanostructures play a pivotal role in various nanophotonic applications.However,a significant challenge arises from the fixed shapes of nanostructures post-fabrication,resulting in limited...Plasmonic modes within metal nanostructures play a pivotal role in various nanophotonic applications.However,a significant challenge arises from the fixed shapes of nanostructures post-fabrication,resulting in limited modes under ordinary illumination.A promising solution lies in far-field control facilitated by spatial light modulators(SLMs),which enable on-site,real-time,and non-destructive manipulation of plasmon excitation.Through the robust modulation of the incident light using SLMs,this approach enables the generation,optimization,and dynamic control of surface plasmon polariton(SPP)and localized surface plasmon(LSP)modes.The versatility of this technique introduces a rich array of tunable degrees of freedom to plasmon-enhanced spectroscopy,offering novel approaches for signal optimization and functional expansion in this field.This paper provides a comprehensive review of the generation and modulation of SPP and LSP modes through far-field control with SLMs and highlights the diverse applications of this optical technology in plasmon-enhanced spectroscopy.展开更多
Localization due to disorder has been one of the most intriguing theoretical concepts that evolved in condensed matter physics.Here,we expand the theory of localization by considering two types of disorders at the sam...Localization due to disorder has been one of the most intriguing theoretical concepts that evolved in condensed matter physics.Here,we expand the theory of localization by considering two types of disorders at the same time,namely,the original Anderson’s disorder and the structural defect disorder,which has been suggested to be a key component in recently discovered two-dimensional amorphous materials.While increasing the degree of both disorders could induce localization of wavefunction in real space,we find that a small degree of structural defect disorder can significantly enhance the localization.As the degree of structural defect disorder increases,localized states quickly appear within the extended phase to enter a broad crossover region with mixed phases.We establish two-dimensional diagrams for the wavefunction localization and conductivity to highlight the interplay between the two types of disorders.Our theoretical model provides a comprehensive understanding of localization in two-dimensional amorphous materials and highlights the promising tunability of their transport properties.展开更多
Neutron production driven by intense lasers utilizing inverse kinematic reactions is explored self-consistently by a combination of particle-in-cell simulations for laser-driven ion acceleration and Monte Carlo nuclea...Neutron production driven by intense lasers utilizing inverse kinematic reactions is explored self-consistently by a combination of particle-in-cell simulations for laser-driven ion acceleration and Monte Carlo nuclear reaction simulations for neutron production.It is proposed that laser-driven light-sail acceleration from ultrathin lithium foils can provide an energetic lithium-ion beam as the projectile bombarding a light hydrocarbon target with sufficiently high flux for the inverse p(^(7)Li,n)reaction to be efficiently achieved.Three-dimensional self-consistent simulations show that a forward-directed pulsed neutron source with ultrashort pulse duration 3 ns,small divergence angle 260,and extremely high peak flux 3×10^(14)n/(cm^(2)·s)can be produced by petawatt lasers at intensities of 10^(21)W/cm^(2).These results indicate that a laser-driven neutron source based on inverse kinematics has promise as a novel compact pulsed neutron generator for practical applications,since the it can operate in a safe and repetitive way with almost no undesirable radiation.展开更多
The non-Hermitian skin effect and edge burst reflect the vital role of spatial boundaries in non-Hermitian systems from both static and dynamic perspectives.In this study,we investigate a non-Hermitian dissipative lat...The non-Hermitian skin effect and edge burst reflect the vital role of spatial boundaries in non-Hermitian systems from both static and dynamic perspectives.In this study,we investigate a non-Hermitian dissipative lattice with nonlocal coupling and demonstrate many interesting static and dynamic phenomena.In the case of global coupling with all sites coupled with each other,we observe anomalous hopping resonance,where a quantum walker initially placed at a single site almost completely escapes from the boundary of the system regardless of its initial position.In the case of non-global coupling,which is infinite-range coupling,the interplay between nonlocal hopping and the non-Hermitian skin effect results in the emergence of local bulk modes exhibiting a multipartite density distribution.The presence of local bulk modes induces the nontrivial dynamics of a quantum walker,which features multiple peaks of lost probability in spatially separated domains.Our findings demonstrate unique properties induced by nonlocal coupling in non-Hermitian systems.展开更多
High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current puri...High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.展开更多
Photonic signal processing offers a versatile and promising toolkit for contemporary scenarios ranging from digital optical communication to analog microwave operation.Compared to its electronic counterpart,it elimina...Photonic signal processing offers a versatile and promising toolkit for contemporary scenarios ranging from digital optical communication to analog microwave operation.Compared to its electronic counterpart,it eliminates inherent bandwidth limitations and meanwhile exhibits the potential to provide unparalleled scalability and flexibility,particularly through integrated photonics.However,by far the on-chip solutions for optical signal processing are often tailored to specific tasks,which lacks versatility across diverse applications.Here,we propose a streamlined chip-level signal processing architecture that integrates different active and passive building blocks in silicon-on-insulator(SOI)platform with a compact and efficient manner.Comprehensive and in-depth analyses for the architecture are conducted at levels of device,system,and application.Accompanied by appropriate configuring schemes,the photonic circuitry supports loading and processing both analog and digital signals simultaneously.Three distinct tasks are facilitated with one single chip across several mainstream fields,spanning optical computing,microwave photonics,and optical communications.Notably,it has demonstrated competitive performance in functions like image processing,spectrum filtering,and electro-optical bandwidth equalization.Boasting high universality and a compact form factor,the proposed architecture is poised to be instrumental for next-generation functional fusion systems.展开更多
Chiral sum-frequency generation(SFG)has proven to be a versatile spectroscopic and imaging tool for probing chirality.However,due to polarization restriction,the conventional chiral SFG microscopes have mostly adopted...Chiral sum-frequency generation(SFG)has proven to be a versatile spectroscopic and imaging tool for probing chirality.However,due to polarization restriction,the conventional chiral SFG microscopes have mostly adopted noncollinear beam configurations,which only partially cover the aperture of microscope and strongly spoil the spatial resolution.In this study,we report the first experimental demonstration of collinear chiral SFG microscopy,which fundamentally supports diffraction-limited resolution.This advancement is attributed to the collinear focus of a radially polarized vectorial beam and a linearly polarized(LP)beam.The tightly focused vectorial beam has a very strong longitudinal component,which interacts with the LP beam and produces the chiral SFG.The collinear configuration can utilize the full aperture and thus push the spatial resolution close to the diffraction limit.This technique can potentially boost the understanding of chiral systems.展开更多
Colloidal CdSe nanoplatelets are thin semiconductor materials with atomic flatness surfaces and one-dimensional strong quantum confinement,and hence they own very narrow and anisotropic emission.Here,we present a poly...Colloidal CdSe nanoplatelets are thin semiconductor materials with atomic flatness surfaces and one-dimensional strong quantum confinement,and hence they own very narrow and anisotropic emission.Here,we present a polydimethylsiloxane(PDMS)assisted transferring method that can pick up single layer CdSe nanoplatelet films self-assembled on a liquid surface and then precisely transfer to a target.By layer-by-layer picking up and transferring,multiple layers of CdSe films can be built up to form CdSe stacks with each single layer having dominant in-plane transition dipole distribution,which both material and energic structures are analogous to traditional multiple quantum wells grown by molecular-beam epitaxy.Additionally,with the great flexibility of colloidal nanoplatelets and this transferring method,CdSe nanoplatelets films can be combined with other materials to form hybrid heterostructures.We transferred a single-layer CdSe film onto WS_(2) flakes,and precisely studied the fast energy transfer rate with controlled CdSe nanoplatelet orientation and by using a streak camera with a ps time resolution.展开更多
Perovskite solar cells have reached a power-conversion efficiency(PCE) of 25.6%,showing great potential with reliable moisture and heat stability.Most results are achieved on small-area devices,using conventional thin...Perovskite solar cells have reached a power-conversion efficiency(PCE) of 25.6%,showing great potential with reliable moisture and heat stability.Most results are achieved on small-area devices,using conventional thin-film processing technologies like spin-coating method.However,such approaches may not be upscaled for large-area substrates.Thus,strategies and materials need to be developed for manufacturing processing routes to realize future commercial photovoltaic fabrications.Notable results have been achieved on large-area perovskite solar cells.In this review,similarities and differences of large-area perovskite fabrication mechanisms between the various pathways are investigated,especially on the parameters affecting the nucleation and crystal growth kinetics.Moreover,the methods for large-area transporting layers and electrodes are discussed,and some key issues from cells to modules.Challenges and opportunities are proposed to pave the way of high-efficiency perovskite solar modules.展开更多
The rotation control of particles in optical tweezers is often subject to the spin or orbit angular momentum induced optical torque,which is susceptible to the mechanical and morphological properties of individual par...The rotation control of particles in optical tweezers is often subject to the spin or orbit angular momentum induced optical torque,which is susceptible to the mechanical and morphological properties of individual particle.Here we report on a robust and high-speed rotation control in optical tweezers by using a novel linear polarization synthesis based on optical heterodyne interference between two circularly polarized lights with opposite handedness.The synthesized linear polarization can be rotated in a hopping-free scheme at arbitrary speed determined electronically by the heterodyne frequency between two laser fields.The experimental demonstration of a trapped vaterite particle in water shows that the precisely controlled rotation frequency of 300 Hz can be achieved.The proposed method will find promising applications in optically driven micro-gears,fluidic pumps and rotational micro-rheology.展开更多
Perovskite lasers,due to their superiority in feasible production and wavelength tunability,find application in optical communication[1].Since the discovery of stimulated emission from CsPbCl3 microcrystalline at liqu...Perovskite lasers,due to their superiority in feasible production and wavelength tunability,find application in optical communication[1].Since the discovery of stimulated emission from CsPbCl3 microcrystalline at liquid-nitrogen temperature[2],successive breakthroughs in perovskite lasers have been made.展开更多
As the main distribution place of deep-level defects and the entrance of water, the interface is critical to determining both the power conversion efficiency(PCE) and the stability of perovskite solar cells(PSCs). Sui...As the main distribution place of deep-level defects and the entrance of water, the interface is critical to determining both the power conversion efficiency(PCE) and the stability of perovskite solar cells(PSCs). Suitable interface design can dramatically passivate interface defects and optimize energy level alignment for suppressing the nonradiative recombination and effectively extracting the photogenerated carriers towards higher PCE. Meanwhile, a proper interface design can also block the interface diffusion of ions for high operational stability. Therefore, interface modification is of great significance to make the PSCs more efficient and stable. Upon optimized material choices, the three-dimensional halide perovskite graded junction layer, low-dimensional halide perovskite interface layer and organic salt passivation layer have been constructed on perovskite films for superior PSCs, yet a systematic review of them is missing. Thus, a guide and summary of recent advances in modulating the perovskite films interface is necessary for the further development of more efficient interface modification.展开更多
The reversal of perpendicular magnetization(PM)by electric control is crucial for high-density integration of low-power magnetic random-access memory.Although the spin-transfer torque and spin-orbit torque technologie...The reversal of perpendicular magnetization(PM)by electric control is crucial for high-density integration of low-power magnetic random-access memory.Although the spin-transfer torque and spin-orbit torque technologies have been used to switch the magnetization of a free layer with perpendicular magnetic anisotropy,the former has limited endurance because of the high current density directly through the junction,while the latter requires an external magnetic field or unconventional configuration to break the symmetry.Here we propose and realize the orbit-transfer torque(OTT),that is,exerting torque on the magnetization using the orbital magnetic moments,and thus demonstrate a new strategy for current-driven PM reversal without external magnetic field.The perpendicular polarization of orbital magnetic moments is generated by a direct current in a few-layer WTe_(2)due to the existence of nonzero Berry curvature dipole,and the polarization direction can be switched by changing the current polarity.Guided by this principle,we construct the WTe_(2)/Fe_(3)GeTe_(2)heterostructures to achieve the OTT driven field-free deterministic switching of PM.展开更多
The quantum Brownian motion model is a typical model in the study of nonequilibrium quantum thermodynamics.Entropy is one of the most fundamental physical concepts in thermodynamics.In this work,by solving the quantum...The quantum Brownian motion model is a typical model in the study of nonequilibrium quantum thermodynamics.Entropy is one of the most fundamental physical concepts in thermodynamics.In this work,by solving the quantum Langevin equation,we study the von Neumann entropy of a particle undergoing quantum Brownian motion.We obtain the analytical expression of the time evolution of the Wigner function in terms of the initial Wigner function.The result is applied to the thermodynamic equilibrium initial state,which reproduces its classical counterpart in the high temperature limit.Based on these results,for those initial states having well-defined classical counterparts,we obtain the explicit expression of the quantum corrections to the entropy in the weak coupling limit.Moreover,we find that for the thermodynamic equilibrium initial state,all terms odd inÿ are exactly zero.Our results bring important insights to the understanding of entropy in open quantum systems.展开更多
基金supported by the National Key R&D Program of China under Grant No.2021YFA1400500the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDB33000000+1 种基金the National Natural Science Foundation of China under Grant No.12334003the Beijing Municipal Natural Science Foundation under Grant Nos.JQ22001 and QY23014。
文摘Establishing the structure-property relationship in amorphous materials has been a long-term grand challenge due to the lack of a unified description of the degree of disorder.In this work,we develop SPRamNet,a neural network based machine-learning pipeline that effectively predicts structure-property relationship of amorphous material via global descriptors.Applying SPRamNet on the recently discovered amorphous monolayer carbon,we successfully predict the thermal and electronic properties.More importantly,we reveal that a short range of pair correlation function can readily encode sufficiently rich information of the structure of amorphous material.Utilizing powerful machine learning architectures,the encoded information can be decoded to reconstruct macroscopic properties involving many-body and long-range interactions.Establishing this hidden relationship offers a unified description of the degree of disorder and eliminates the heavy burden of measuring atomic structure,opening a new avenue in studying amorphous materials.
基金the support by the fund of the National Key Research and Development Program of China (Grant No. 2024YFA1208800)National Natural Science Foundation of China (NSFC) (Grant No. U23A20358)+2 种基金Natural Science Foundation of Shandong Province (Grant Nos. ZR2023ZD05 and 2022TSGC2120)the Shenzhen Fundamental Research Program (Grant No. GJHZ20220913142605011)Xiaomi Foundation/Xiaomi Young Talents Program
文摘The transition of cobalt ions located at tetrahedral sites will produce strong absorption in the visible and nearinfrared regions,and is expected to work in a passively Q-switched solid-state laser at the eye-safe wavelength of 1.5μm.In this study,Co^(2+)ions were introduced into the wide bandgap semiconductor material ZnGa_(2)O_(4),and large-sized and high-quality Co^(2+)-doped ZnGa_(2)O_(4)crystals with a volume of about 20 cm^(3)were grown using the vertical gradient freeze(VGF)method.Crystal structure and optical properties were analyzed using X-ray powder diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and absorption spectroscopy.XRD results show that the Co^(2+)-doped ZnGa_(2)O_(4)crystal has a pure spinel phase without impurity phases and the rocking curve full width at half maximum(FWHM)is only 58 arcsec.The concentration of Co^(2+)in Co^(2+)-doped ZnGa_(2)O_(4)crystals was determined to be 0.2 at.%by the energy dispersive X-ray spectroscopy.The optical band gap of Co^(2+)-doped ZnGa_(2)O_(4)crystals is 4.44 eV.The optical absorption spectrum for Co^(2+)-doped ZnGa_(2)O_(4)reveals a prominent visible absorption band within 550−670 nm and a wide absorption band spanning from 1100 to 1700 nm.This suggests that the Co^(2+)ions have substituted the Zn^(2+)ions,which are typically tetrahedrally coordinated,within the lattice structure of ZnGa_(2)O_(4).The visible region's absorption peak and the near-infrared broad absorption band are ascribed to the^(4)A_(2)(4F)→^(4)T_(1)(4P)and 4A2(4F)→^(4)T_(1)(4F)transitions,respectively.The optimal ground state absorption cross section was determined to be 3.07×10^(−19)cm^(2)in ZnGa_(2)O_(4),a value that is comparatively large within the context of similar materials.This finding suggests that ZnGa_(2)O_(4)is a promising candidate for use in near-infrared passive Q-switched solid-state lasers.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFC3401100 and 2022YFF0712500)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030009)+2 种基金the National Natural Science Foundation of China(Grant Nos.12204017,12004012,12004013,12041602,91750203,91850111,and 92150301)the China Postdoctoral Science Foundation(Grant No.2020M680220 and 2020M680230)the Clinical Medicine Plus X-Young Scholars Project,Peking University,Fundamental Research Funds for the Central Universities.
文摘Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a critical role during poling fabrication.To enhance the imaging detection efficiency of the domain structure in z-cut PPLN,we have developed a second-harmonic generation microscope system specifically designed to produce a longitudinal electric field in foci for the imaging domain inversion.We demonstrated that imaging using a longitudinal electric field can achieve a contrast ratio enhancement by a factor of 1.77,showing high imaging efficiency and making the proposed method suitable for in situ monitoring of the z-cut PPLN poling process.
基金supported by the National Natural Science Foundation of China(Grant Nos.12474370,11974032,12161141010,and T2325022)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301500).
文摘Multiphoton entanglement with high information capacity plays an essential role in quantum information processing.The appearance of parallel beam splitting(BS)in a gradient metasurface provides the chance to prepare the multiphoton entanglement in one step.Here,we use a single metasurface to construct multiphoton path-polarization entanglement.Based on the parallel BS property,entanglement among N unentangled photons is created after they pass through a gradient metasurface.Also,with this ability,entanglement fusion among several pairs of entangled photons is set up,which can greatly enlarge the entanglement dimension.These theoretical results pave the way for manipulating metasurface-based multiphoton entanglement,which holds great promise for ultracompact on-chip quantum information processing.
基金supported by the National Key Research&Development Program of China(Grant Nos.2022YFA1403500 and 2021YFA1400500)the National Science Foundation of China(Grant Nos.62321004,12234001,and 12474215)+1 种基金supported by New Cornerstone Science Foundationa fellowship and a CRF award from the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant Nos.HKUST SRFS2324-6S01 and C7037-22GF)。
文摘Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus on one unique quantum phase induced by the electron-hole interaction in two-dimensional systems,known as“exciton insulators”(EIs).Although this phase of matter has been studied for more than half a century,suitable platforms for its stable realization remain scarce.We provide an overview of the strategies to realize EIs in accessible materials and structures,along with a discussion on some unique properties of EIs stemming from the band structures of these materials.Additionally,signatures in experiments to distinguish EIs are discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.12074265,12234002,and 92250303)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010329)。
文摘Based on numerical solutions of the time-dependent Schr ¨odinger equation, we theoretically investigate the photoelectron spectrum of hydrogen atoms ionized by a pair of ultrashort, intense, and orthogonally polarized laser pulses with a relative time delay in a pump–probe configuration. The pump pulse resonantly excites electrons from the 1s and 2p levels,inducing Rabi oscillations. The resulting dynamically enhanced Autler–Townes(AT) splitting is observed in the photoelectron energy spectrum upon interaction with the second probe pulse. In contrast to the previous parallel-polarization scheme, the proposed orthogonal-polarization configuration enables the resolution of dynamically enhanced AT splitting over a considerably wider range of probe photon energies.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030009)the National Key Research and Development Program of China(Grant No.2022YFA1604304)the National Natural Science Foundation of China(Grant No.92250305).
文摘Plasmonic modes within metal nanostructures play a pivotal role in various nanophotonic applications.However,a significant challenge arises from the fixed shapes of nanostructures post-fabrication,resulting in limited modes under ordinary illumination.A promising solution lies in far-field control facilitated by spatial light modulators(SLMs),which enable on-site,real-time,and non-destructive manipulation of plasmon excitation.Through the robust modulation of the incident light using SLMs,this approach enables the generation,optimization,and dynamic control of surface plasmon polariton(SPP)and localized surface plasmon(LSP)modes.The versatility of this technique introduces a rich array of tunable degrees of freedom to plasmon-enhanced spectroscopy,offering novel approaches for signal optimization and functional expansion in this field.This paper provides a comprehensive review of the generation and modulation of SPP and LSP modes through far-field control with SLMs and highlights the diverse applications of this optical technology in plasmon-enhanced spectroscopy.
基金supported by the National Natural Science Foundation of China(Grant No.92165101)the National Key R&D Program of China(Grant No.2021YFA1400500)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)the Beijing Natural Science Foundation(Grant No.JQ22001).We are grateful for computational resources supported by High-performance Computing Platform of Peking University.
文摘Localization due to disorder has been one of the most intriguing theoretical concepts that evolved in condensed matter physics.Here,we expand the theory of localization by considering two types of disorders at the same time,namely,the original Anderson’s disorder and the structural defect disorder,which has been suggested to be a key component in recently discovered two-dimensional amorphous materials.While increasing the degree of both disorders could induce localization of wavefunction in real space,we find that a small degree of structural defect disorder can significantly enhance the localization.As the degree of structural defect disorder increases,localized states quickly appear within the extended phase to enter a broad crossover region with mixed phases.We establish two-dimensional diagrams for the wavefunction localization and conductivity to highlight the interplay between the two types of disorders.Our theoretical model provides a comprehensive understanding of localization in two-dimensional amorphous materials and highlights the promising tunability of their transport properties.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1603200 and 2022YFA1603201)the National Natural Science Foundation of China(Grant Nos.12135001,11825502,and 11921006)+1 种基金the Strategic Priority Research Program of CAS(Grant No.XDA25050900)the National Natural Science Funds for Distinguished Young Scholars(Grant No.11825502)。
文摘Neutron production driven by intense lasers utilizing inverse kinematic reactions is explored self-consistently by a combination of particle-in-cell simulations for laser-driven ion acceleration and Monte Carlo nuclear reaction simulations for neutron production.It is proposed that laser-driven light-sail acceleration from ultrathin lithium foils can provide an energetic lithium-ion beam as the projectile bombarding a light hydrocarbon target with sufficiently high flux for the inverse p(^(7)Li,n)reaction to be efficiently achieved.Three-dimensional self-consistent simulations show that a forward-directed pulsed neutron source with ultrashort pulse duration 3 ns,small divergence angle 260,and extremely high peak flux 3×10^(14)n/(cm^(2)·s)can be produced by petawatt lasers at intensities of 10^(21)W/cm^(2).These results indicate that a laser-driven neutron source based on inverse kinematics has promise as a novel compact pulsed neutron generator for practical applications,since the it can operate in a safe and repetitive way with almost no undesirable radiation.
基金National Natural Science Foundation of China(Grant Nos.12074428 and 92265208)the National Key R&D Program of China(Grant No.2022YFA1405300).
文摘The non-Hermitian skin effect and edge burst reflect the vital role of spatial boundaries in non-Hermitian systems from both static and dynamic perspectives.In this study,we investigate a non-Hermitian dissipative lattice with nonlocal coupling and demonstrate many interesting static and dynamic phenomena.In the case of global coupling with all sites coupled with each other,we observe anomalous hopping resonance,where a quantum walker initially placed at a single site almost completely escapes from the boundary of the system regardless of its initial position.In the case of non-global coupling,which is infinite-range coupling,the interplay between nonlocal hopping and the non-Hermitian skin effect results in the emergence of local bulk modes exhibiting a multipartite density distribution.The presence of local bulk modes induces the nontrivial dynamics of a quantum walker,which features multiple peaks of lost probability in spatially separated domains.Our findings demonstrate unique properties induced by nonlocal coupling in non-Hermitian systems.
基金Project supported by the Basic and Applied Basic Research Foundation of Guangdong Province,China(Grant Nos.2019A1515110302 and 2022A1515140003)the Key Research and Development Program of Guangdong Province,China(Grant Nos.2020B010189001,2021B0301030002,2019B010931001,and 2018B030327001)+5 种基金the National Natural Science Foundation of China(Grant Nos.52172035,52025023,52322205,51991342,52021006,51991344,52100115,11888101,92163206,12104018,and 12274456)the National Key Research and Development Program of China(Grant Nos.2021YFB3200303,2022YFA1405600,2018YFA0703700,2021YFA1400201,and 2021YFA1400502)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Pearl River Talent Recruitment Program of Guangdong Province,China(Grant No.2019ZT08C321)China Postdoctoral Science Foundation(Grant Nos.2020T130022 and 2020M680178)the Science and Technology Plan Project of Liaoning Province,China(Grant No.2021JH2/10100012).
文摘High-purity copper(Cu) with excellent thermal and electrical conductivity, is crucial in modern technological applications, including heat exchangers, integrated circuits, and superconducting magnets. The current purification process is mainly based on the zone/electrolytic refining or anion exchange, however, which excessively relies on specific integrated equipment with ultra-high vacuum or chemical solution environment, and is also bothered by external contaminants and energy consumption. Here we report a simple approach to purify the Cu foils from 99.9%(3N) to 99.99%(4N) by a temperature-gradient thermal annealing technique, accompanied by the kinetic evolution of single crystallization of Cu.The success of purification mainly relies on(i) the segregation of elements with low effective distribution coefficient driven by grain-boundary movements and(ii) the high-temperature evaporation of elements with high saturated vapor pressure.The purified Cu foils display higher flexibility(elongation of 70%) and electrical conductivity(104% IACS) than that of the original commercial rolled Cu foils(elongation of 10%, electrical conductivity of ~ 100% IACS). Our results provide an effective strategy to optimize the as-produced metal medium, and therefore will facilitate the potential applications of Cu foils in precision electronic products and high-frequency printed circuit boards.
基金supported by the National Key Research and Development Program of China(2022YFB2803700)the National Natural Science Foundation of China(62235002,62322501,12204021,62105008,62235003,and 62105260)+5 种基金Beijing Municipal Science and Technology Commission(Z221100006722003)Beijing Municipal Natural Science Foundation(Z210004)China Postdoctoral Science Foundation(2021T140004)Major Key Project of PCL,the Natural Science Basic Research Program of Shaanxi Province(2022 JQ-638)Young Talent fund of University Association for Science and Technology in Shaanxi,China(20220135)Young Talent fund of Xi'an Association for science and technology(095920221308).
文摘Photonic signal processing offers a versatile and promising toolkit for contemporary scenarios ranging from digital optical communication to analog microwave operation.Compared to its electronic counterpart,it eliminates inherent bandwidth limitations and meanwhile exhibits the potential to provide unparalleled scalability and flexibility,particularly through integrated photonics.However,by far the on-chip solutions for optical signal processing are often tailored to specific tasks,which lacks versatility across diverse applications.Here,we propose a streamlined chip-level signal processing architecture that integrates different active and passive building blocks in silicon-on-insulator(SOI)platform with a compact and efficient manner.Comprehensive and in-depth analyses for the architecture are conducted at levels of device,system,and application.Accompanied by appropriate configuring schemes,the photonic circuitry supports loading and processing both analog and digital signals simultaneously.Three distinct tasks are facilitated with one single chip across several mainstream fields,spanning optical computing,microwave photonics,and optical communications.Notably,it has demonstrated competitive performance in functions like image processing,spectrum filtering,and electro-optical bandwidth equalization.Boasting high universality and a compact form factor,the proposed architecture is poised to be instrumental for next-generation functional fusion systems.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2020B0301030009)the National Natural Science Foundation of China (Grant Nos.91750203,91850111,11174019,12004013,92150301,and 61322509)+1 种基金the Ministry of Science and Technology of China[National Basic Research Program of China (Grant No.2013CB921904)]the China Postdoctoral Science Foundation (Grant No.2020M680220).
文摘Chiral sum-frequency generation(SFG)has proven to be a versatile spectroscopic and imaging tool for probing chirality.However,due to polarization restriction,the conventional chiral SFG microscopes have mostly adopted noncollinear beam configurations,which only partially cover the aperture of microscope and strongly spoil the spatial resolution.In this study,we report the first experimental demonstration of collinear chiral SFG microscopy,which fundamentally supports diffraction-limited resolution.This advancement is attributed to the collinear focus of a radially polarized vectorial beam and a linearly polarized(LP)beam.The tightly focused vectorial beam has a very strong longitudinal component,which interacts with the LP beam and produces the chiral SFG.The collinear configuration can utilize the full aperture and thus push the spatial resolution close to the diffraction limit.This technique can potentially boost the understanding of chiral systems.
基金supported by Beijing Natural Science Foundation(grant no.Z190005)the National Natural Science Foundation of China(grant nos.61875002)the National Key R&D Program of China(grant no.2018YFA0306302)。
文摘Colloidal CdSe nanoplatelets are thin semiconductor materials with atomic flatness surfaces and one-dimensional strong quantum confinement,and hence they own very narrow and anisotropic emission.Here,we present a polydimethylsiloxane(PDMS)assisted transferring method that can pick up single layer CdSe nanoplatelet films self-assembled on a liquid surface and then precisely transfer to a target.By layer-by-layer picking up and transferring,multiple layers of CdSe films can be built up to form CdSe stacks with each single layer having dominant in-plane transition dipole distribution,which both material and energic structures are analogous to traditional multiple quantum wells grown by molecular-beam epitaxy.Additionally,with the great flexibility of colloidal nanoplatelets and this transferring method,CdSe nanoplatelets films can be combined with other materials to form hybrid heterostructures.We transferred a single-layer CdSe film onto WS_(2) flakes,and precisely studied the fast energy transfer rate with controlled CdSe nanoplatelet orientation and by using a streak camera with a ps time resolution.
基金supported by the National Key Research and Development Program of China(Nos.2019YFA0707003 and 2019YFE0114100)the National Natural Science Foundation of China(NSFC 51872007)Beijing Municipal Natural Science Foundation(No.7202094).
文摘Perovskite solar cells have reached a power-conversion efficiency(PCE) of 25.6%,showing great potential with reliable moisture and heat stability.Most results are achieved on small-area devices,using conventional thin-film processing technologies like spin-coating method.However,such approaches may not be upscaled for large-area substrates.Thus,strategies and materials need to be developed for manufacturing processing routes to realize future commercial photovoltaic fabrications.Notable results have been achieved on large-area perovskite solar cells.In this review,similarities and differences of large-area perovskite fabrication mechanisms between the various pathways are investigated,especially on the parameters affecting the nucleation and crystal growth kinetics.Moreover,the methods for large-area transporting layers and electrodes are discussed,and some key issues from cells to modules.Challenges and opportunities are proposed to pave the way of high-efficiency perovskite solar modules.
基金the National Natural Science Foundation of China(91750203 and 91850111)State Key Laboratory of Applied Optics,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences and the High-performance Computing Platform of Peking University.
文摘The rotation control of particles in optical tweezers is often subject to the spin or orbit angular momentum induced optical torque,which is susceptible to the mechanical and morphological properties of individual particle.Here we report on a robust and high-speed rotation control in optical tweezers by using a novel linear polarization synthesis based on optical heterodyne interference between two circularly polarized lights with opposite handedness.The synthesized linear polarization can be rotated in a hopping-free scheme at arbitrary speed determined electronically by the heterodyne frequency between two laser fields.The experimental demonstration of a trapped vaterite particle in water shows that the precisely controlled rotation frequency of 300 Hz can be achieved.The proposed method will find promising applications in optically driven micro-gears,fluidic pumps and rotational micro-rheology.
基金supported by the National Natural Science Foundation of China(11874074 and 11527901)the National Natural Science Foundation of China(51773045,21772030,51922032,and 21961160720)for financial support+2 种基金the National Key Research and Development Program of China(2018YFA0704400)the National Key Research and Development Program of China(2017YFA0206600)Guangdong Major Project of Basic and Applied Basic Research(2020B0301030009)。
文摘Perovskite lasers,due to their superiority in feasible production and wavelength tunability,find application in optical communication[1].Since the discovery of stimulated emission from CsPbCl3 microcrystalline at liquid-nitrogen temperature[2],successive breakthroughs in perovskite lasers have been made.
基金supported by the National Key Research and Development Program of China (Grant Nos. 2019YFA0707003 and 2019YFE0114100)the National Natural Science Foundation of China (Grant No. 51872007)Beijing Municipal Natural Science Foundation, China (Grant No. 7202094)。
文摘As the main distribution place of deep-level defects and the entrance of water, the interface is critical to determining both the power conversion efficiency(PCE) and the stability of perovskite solar cells(PSCs). Suitable interface design can dramatically passivate interface defects and optimize energy level alignment for suppressing the nonradiative recombination and effectively extracting the photogenerated carriers towards higher PCE. Meanwhile, a proper interface design can also block the interface diffusion of ions for high operational stability. Therefore, interface modification is of great significance to make the PSCs more efficient and stable. Upon optimized material choices, the three-dimensional halide perovskite graded junction layer, low-dimensional halide perovskite interface layer and organic salt passivation layer have been constructed on perovskite films for superior PSCs, yet a systematic review of them is missing. Thus, a guide and summary of recent advances in modulating the perovskite films interface is necessary for the further development of more efficient interface modification.
基金supported by the National Natural Science Foundation of China(Grant Nos.91964201 and 61825401)。
文摘The reversal of perpendicular magnetization(PM)by electric control is crucial for high-density integration of low-power magnetic random-access memory.Although the spin-transfer torque and spin-orbit torque technologies have been used to switch the magnetization of a free layer with perpendicular magnetic anisotropy,the former has limited endurance because of the high current density directly through the junction,while the latter requires an external magnetic field or unconventional configuration to break the symmetry.Here we propose and realize the orbit-transfer torque(OTT),that is,exerting torque on the magnetization using the orbital magnetic moments,and thus demonstrate a new strategy for current-driven PM reversal without external magnetic field.The perpendicular polarization of orbital magnetic moments is generated by a direct current in a few-layer WTe_(2)due to the existence of nonzero Berry curvature dipole,and the polarization direction can be switched by changing the current polarity.Guided by this principle,we construct the WTe_(2)/Fe_(3)GeTe_(2)heterostructures to achieve the OTT driven field-free deterministic switching of PM.
基金support from the National Science Foundation of China under Grants Nos.11775001,11534002,and 11825001.
文摘The quantum Brownian motion model is a typical model in the study of nonequilibrium quantum thermodynamics.Entropy is one of the most fundamental physical concepts in thermodynamics.In this work,by solving the quantum Langevin equation,we study the von Neumann entropy of a particle undergoing quantum Brownian motion.We obtain the analytical expression of the time evolution of the Wigner function in terms of the initial Wigner function.The result is applied to the thermodynamic equilibrium initial state,which reproduces its classical counterpart in the high temperature limit.Based on these results,for those initial states having well-defined classical counterparts,we obtain the explicit expression of the quantum corrections to the entropy in the weak coupling limit.Moreover,we find that for the thermodynamic equilibrium initial state,all terms odd inÿ are exactly zero.Our results bring important insights to the understanding of entropy in open quantum systems.
