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Chinese physics Letters 2024年第4期41卷 118-123页

作者：詹红星林玉尺赵宇清左海艳王兴玉马肖燕李春红罗会仟陈根富李世亮任聪 School of physics and Astronomy Yunnan UniversityKunming 650500China Beijing national laboratory for Condensed Matter physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190China Yunnan key laboratory for Electromagnetic Materials and Devices Yunnan UniversityKunming 650500China

We report on soft c-axis point-contact Andreev reflection(PCAR)spectroscopy combining with resistivity measurements on BaFe_(2)(As_(0.7)P_(0.3))_(2),to elucidate the superconducting gap structure in the vicinity of the quantum critical point.A double peak at the gap edge plus a dip feature at zero-bias has been observed on the PCAR spectra,indicative of the presence of a nodeless gap in BaFe_(2)(As_(0.7)P_(0.3))_(2).Detailed analysis within a sophisticated theoretical model reveals an anisotropic gap with deep gap minima.The PCARs also feature additional structures related to the electron-bosonic coupling mode.Using the extracted superconducting energy gap value,a characteristic bosonic energy Ω_(b) and its temperature dependence are obtained,comparable with the spin-resonance energy observed in neutron scattering experiment.These results indicate a magnetism-driven quantum critical point in the BaFe_(2)(As_(1-x)P_(x))_(2) system.

关键词： quantum critical resistivity

Large magnetostriction of Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites in a wide temperature range

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Journal of Rare Earths 2024年第4期42卷 705-709页

作者： Hehe Ding Yangguang Shi Shaolong Tang MIIT key laboratory of Aerospace Information Materials and physics Department of Applied PhysicsNanjing University of Aeronautics and AstronauticsNanjing210016China national laboratory of Solid State Microstructures Nanjing UniversityNanjing210093China

We report the magnetostrictive performance of the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites.Measurement of M?ssbauer spectra and the XRD results indicate that the easy magnetic direction of the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)compound is alongdirection with spontaneous magnetostrictionλ111 of1900 ppm.The-oriented Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites with particle volume fractions of20 vol%-55 vol%were prepared.Magnetization measurements demonstrate that the composite is highly anisotropic.The raw material cost of Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)is about 85%of that of the Terfenol-D(Tb_(0.3)Dy_(0.7)Fe_(2))composition.Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composites possess comparable magnetostriction with those composites made of Tb_(0.3)Dy_(0.7)Fe_(2)particles.At room temperature,the magnetostrictionλ_Ⅱof the Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93)/epoxy composite reaches 420 ppm at a low field of 80 kA/m and about1000 ppm at 239 kA/m.In addition,the composite exhibits a large saturation magnetostrictionλ_Ⅱover1200 ppm from 300 to 100 K,suggesting its potential applications as a low-cost magnetostrictive material in a wide temperature range.Therefore,the current study offers an opportunity to widen the operating temperature range of the magnetostrictive composite.

关键词： Magnetostrictive composite Nd_(0.2)Tb_(0.3)Dy_(0.5)Fe_(1.93) Wide temperaturerange Laves phase Rare earths

Twin-Capture Rydberg State Excitation Enhanced with Few-Cycle Laser Pulses

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Chinese physics Letters 2024年第1期41卷 6-10页

作者：赵晶刘金磊王小伟赵增秀 Department of physics National University of Defense TechnologyChangsha 410073China Hunan key laboratory of Extreme Matter and Applications National University of Defense TechnologyChangsha 410073China

Quantum excitation is usually regarded as a transient process occurring instantaneously,leaving the underlying physics shrouded in mystery.Recent research shows that Rydberg-state excitation with ultrashort laser pulses can be investigated and manipulated with state-of-the-art few-cycle pulses.We theoretically find that the efficiency of Rydberg state excitation can be enhanced with a short laser pulse and modulated by varying the laser intensities.We also uncover new facets of the excitation dynamics,including the launching of an electron wave packet through strong-field ionization,the re-entry of the electron into the atomic potential and the crucial step where the electron makes a U-turn,resulting in twin captures into Rydberg orbitals.By tuning the laser intensity,we show that the excitation of the Rydberg state can be coherently controlled on a sub-optical-cycle timescale.Our work paves the way toward ultrafast control and coherent manipulation of Rydberg states,thus benefiting Rydberg-state-based quantum technology.

关键词： Rydberg excitation coherent

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Light(Science & Applications) 2024年第2期13卷 333-346页

作者： Yifan Sun Qian Li Ling-Jun Kong Xiangdong Zhang key laboratory of advanced optoelectronic quantum architecture and measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology100081BeijingChina

Compared with electrical neural networks,optical neural networks(ONNs)have the potentials to break the limit of the bandwidth and reduce the consumption of energy,and therefore draw much attention in recent years.By far,several types of ONNs have been implemented.However,the current ONNs cannot realize the acceleration as powerful as that indicated by the models like quantum neural networks.How to construct and realize an ONN with the quantum speedup is a huge challenge.Here,we propose theoretically and demonstrate experimentally a new type of optical convolutional neural network by introducing the optical correlation.It is called the correlated optical convolutional neural network(COCNN).We show that the COCNN can exhibit“quantum speedup”in the training process.The character is verified from the two aspects.One is the direct illustration of the faster convergence by comparing the loss function curves of the COCNN with that of the traditional convolutional neural network(CNN).Such a result is compatible with the training performance of the recently proposed quantum convolutional neural network(QCNN).The other is the demonstration of the COCNN’s capability to perform the QCNN phase recognition circuit,validating the connection between the COCNN and the QCNN.Furthermore,we take the COCNN analog to the 3-qubit QCNN phase recognition circuit as an example and perform an experiment to show the soundness and the feasibility of it.The results perfectly match the theoretical calculations.Our proposal opens up a new avenue for realizing the ONNs with the quantum speedup,which will benefit the information processing in the era of big data.

关键词： process quantum convolution

Rational design multi-color-emissive chemiluminescent carbon nanodots in a single solvothermal reaction

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Nano Research 2024年第6期17卷 4651-4660页

作者： Guang-Song Zheng Cheng-Long Shen Yuan Deng Kai-Kai Liu Jin-Hao Zang Lin Dong Qing Lou Chong-Xin Shan Henan key laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Materials PhysicsMinistry of Educationand School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China

Recently,the chemiluminescence(CL)induced by carbon nanodots(CDs)has intrigued researchers’extensive interests in various applications due to its special light emission principle.However,the difficulty of synthesizing chemiluminescent CDs with full-spectrum emission severely hinders the further regulation of the CL emission mechanism.Herein,the multi-color-emissive chemiluminescent CDs are rational designed and further synthesized by regulating the sp2-hybrid core and sp3-hybrid surface from the citrate-ammonia molecular in a single solvothermal reaction.More experimental characterizations and density functional theory calculations reveal that the higher temperature can promote the crosslinking polymerization/carbonization of carbon core and the higher protonation of solvent can determine the core size of final CDs,resulting in the variant CL emission from molecular-,crosslinking-and core-states.Thus,the CL emission of the CDs can be further synthesized by tuning the luminescence chromophores in the formation process via regulating the temperature and solvent,enabling the applications of the CL CDs in illumination and information encryption.This study paves a new technology to understand the luminescence of CDs and affords an industry translational potential over traditional chemiluminescent molecular.

关键词： carbon nanodots chemiluminescence regulation energy level alignment mechanism

Bethe ansatz solutions of the 1D extended Hubbard-model

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Communications in Theoretical physics 2024年第4期76卷 43-50页

作者：侯海洋孙佩乔艺许小甜张鑫杨涛 Institute of Modern physics Northwest University Xian 710127 China Shaanxi key laboratory for Theoretical physics Frontiers Xian 710127 China Beijing national laboratory for Condensed Matter Institute of physics Chinese Academy of Sciences Beijing 100190 China

We construct an integrable 1D extended Hubbard model within the framework of the quantum inverse scattering method.With the help of the nested algebraic Bethe ansatz method,the eigenvalue Hamiltonian problem is solved... 详细信息

关键词： quantum integrable system Bethe ansatz T-Q relation Hubbard model

Road map for, and technical challenges of, carbon-nanotube integrated circuit technology

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national Science Review 2024年第3期11卷 14-16页

作者： Jia Si Panpan Zhang Zhiyong Zhang key laboratory for the physics and Chemistry of Nanodevices and Center for Carbon-based Electronics School of Electronics Peking University State key laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications

The past decade has witnessed an explosion of research on carbon-nanotube(CNT) electronics due to their outstanding properties, including an ultrathin body, a high carrier mobility and a high saturation velocity.

关键词： TRANSISTORS

Scaling laws governing the elastic properties of 3D graphenes

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Science China Technological Sciences 2024年第6期67卷 1748-1756页

作者： LI Ming LU Guo YU HaoDong LI MengLei ZHENG FaWei Centre for Quantum physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of Technology Beijing key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of Technology laboratory of Computational physics Institute of Applied Physics and Computational Mathematics Department of physics Capital Normal University

In this study, we comprehensively investigated the scaling law for elastic properties of three-dimensional honeycomb-like graphenes（3D graphenes） using hybrid neural network potential-based molecular dynamics simulations and theoretical analyses. The elastic constants were obtained as functions of honeycomb hole size, denoted by the graphene wall length L. All five independent elastic constants in the large-L limit are proportional to L-1. The associated coefficients are combinations of elastic constants of two-dimensional graphene. High-order terms including L-2and L-3emerge for finite L values. They have three origins, the distorted areas close to the joint lines of 3D graphenes, the variation in solid angles between graphene plates, and the bending distortion of graphene plates. Significantly, the chirality becomes essential with decreasing L because the joint line structures are different between the armchair and zigzag-type 3D graphenes. Our findings provide insights into the elastic properties of graphene-based superstructures and can be used for further studies on graphene-based materials.

关键词： scaling law neural network elastic properties 3D graphene

Detecting bulk and edge exceptional points in non-Hermitian systems through generalized Petermann factors

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Frontiers of physics 2024年第2期19卷 169-177页

作者： Yue-Yu Zou Yao Zhou Li-Mei Chen Peng Ye School of physics State Key Laboratory of Optoelectronic Materials and Technologiesand Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSun Yat-sen UniversityGuangzhou 510275China

Non-orthogonality in non-Hermitian quantum systems gives rise to tremendous exotic quantum phenomena,which can be fundamentally traced back to non-unitarity.In this paper,we introduce an interesting quantity(denoted asη)as a new variant of the Petermann factor to directly and efficiently measure non-unitarity and the associated non-Hermitian physics.By tuning the model parameters of underlying non-Hermitian systems,we find that the discontinuity of bothηand its first-order derivative(denoted as■η)pronouncedly captures rich physics that is fundamentally caused by non-unitarity.More concretely,in the 1D non-Hermitian topological systems,two mutually orthogonal edge states that are respectively localized on two boundaries become non-orthogonal in the vicinity of discontinuity ofηas a function of the model parameter,which is dubbed"edge state transition".Through theoretical analysis,we identify that the appearance of edge state transition indicates the existence of exceptional points(EPs)in topological edge states.Regarding the discontinuity of■η,we investigate a two-level non-Hermitian model and establish a connection between the points of discontinuity of■ηand EPs of bulk states.By studying this connection in more general lattice models,we find that some models have discontinuity of■η,implying the existence of EPs in bulk states.

关键词： non-Hermitian Su−Schrieffer−Heeger(SSH)model exceptional point

Spin‑controlled topological phase transition in non‑Euclidean space

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Frontiers of Optoelectronics 2024年第1期17卷 67-76页

作者： Zhuochen Du Jinze Gao Qiuchen Yan Cuicui Lu Xiaoyong Hu Qihuang Gong State key laboratory for Mesoscopic physics and Department of physics Collaborative Innovation Center of Quantum Matter and Frontiers Science Center for Nano‑OptoelectronicsBeijing Academy of Quantum Information SciencesPeking UniversityBeijing 100871China key laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of TechnologyBeijing 100081China Peking University Yangtze Delta Institute of Optoelectronics Nantong 226010China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Hefei national laboratory Hefei 230088China

Modulation of topological phase transition has been pursued by researchers in both condensed matter and optics research fields,and has been realized in Euclidean systems,such as topological photonic crystals,topological metamaterials,and coupled resonator arrays.However,the spin-controlled topological phase transition in non-Euclidean space has not yet been explored.Here,we propose a non-Euclidean configuration based on Mobius rings,and we demonstrate the spin-controlled transition between the topological edge state and the bulk state.The Mobius ring,which is designed to have an 8πperiod,has a square cross section at the twist beginning and the length/width evolves adiabatically along the loop,accompanied by conversion from transverse electric to transverse magnetic modes resulting from the spin-locked effect.The 8πperiod Mobius rings are used to construct Su–Schrieffer–Heeger configuration,and the configuration can support the topological edge states excited by circularly polarized light,and meanwhile a transition from the topological edge state to the bulk state can be realized by controlling circular polarization.In addition,the spin-controlled topological phase transition in non-Euclidean space is feasible for both Hermitian and non-Hermitian cases in 2D systems.This work provides a new degree of polarization to control topological photonic states based on the spin of Mobius rings and opens a way to tune the topological phase in non-Euclidean space.

关键词： Topological phase transition Non-Euclidean space Möbius ring Spin-locked effect