For now, just few researchers have analyzed the thermal-mechanical mirror buckling behavior of freestanding graphene membranes discovered in scan tunneling microscope experiments. Ones of the potential applies of the out-of-plane deformational behavior of graphene membranes are energy harvesting systems. Whatever in the experiments, or for energy harvesting systems, the graphene membranes are micron order. According to previous researches, traditional molecular dynamics method is an appropriate approach to express mirror buckling with nano scale. However, due to the limit of algorithm, when dealing with micro size model by molecular dynamics method, the problems of low computational efficiency and too long calculational time may arise. Therefore, for analyzing the mirror buckling of micro size graphene membranes, the coarse-grained molecular dynamics method is utilized in this paper. Graphene membranes with a fan-shaped cross section and various depth-span ratios are under mechanical or thermal loads. Influences of every factor on the mirror buckling are explored. The calculations indicated that for graphene membranes with various depth-span ratios under mechanical load mirror buckling could be observed. And the critical loading increases with the depth-span ratio. Under thermal load graphene membranes only with low depth-span ratios could totally overturn. For high depth-span ratio graphene, the center height decreases with temperature rise. However, it is hard to overturn completely. Understanding the influences of various factors on the mirror buckling phenomenon of graphene membranes provides theoretical guidance for the design of energy harvesting systems.
{"title":"The mirror buckling analysis of freestanding graphene membranes based on the coarse-grained molecular dynamics method","authors":"None Xu Wenlong, None Kai Yue, None Zhang Kai, None Zheng Balin","doi":"10.7498/aps.72.20231120","DOIUrl":"https://doi.org/10.7498/aps.72.20231120","url":null,"abstract":"For now, just few researchers have analyzed the thermal-mechanical mirror buckling behavior of freestanding graphene membranes discovered in scan tunneling microscope experiments. Ones of the potential applies of the out-of-plane deformational behavior of graphene membranes are energy harvesting systems. Whatever in the experiments, or for energy harvesting systems, the graphene membranes are micron order. According to previous researches, traditional molecular dynamics method is an appropriate approach to express mirror buckling with nano scale. However, due to the limit of algorithm, when dealing with micro size model by molecular dynamics method, the problems of low computational efficiency and too long calculational time may arise. Therefore, for analyzing the mirror buckling of micro size graphene membranes, the coarse-grained molecular dynamics method is utilized in this paper. Graphene membranes with a fan-shaped cross section and various depth-span ratios are under mechanical or thermal loads. Influences of every factor on the mirror buckling are explored. The calculations indicated that for graphene membranes with various depth-span ratios under mechanical load mirror buckling could be observed. And the critical loading increases with the depth-span ratio. Under thermal load graphene membranes only with low depth-span ratios could totally overturn. For high depth-span ratio graphene, the center height decreases with temperature rise. However, it is hard to overturn completely. Understanding the influences of various factors on the mirror buckling phenomenon of graphene membranes provides theoretical guidance for the design of energy harvesting systems.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135495742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Growth of lithium dendrites in solid state batteries is an important factor that disturbs their commercial applications. The growth of lithium dendrites at the interface of lithium metal anode will not only lead to the decrease of battery energy efficiency, but also cause combustion, explosion and other safety problems. In order to explore the factors and methods that inhibit the growth of lithium dendrites, the phase-field theory is used to simulate the growth of lithium dendrites in polymer solid electrolyte batteries, and a phase-field model of lithium dendrite growth coupled with mechanical stress and thermal field is established. The effects of key physical factors such as ambient temperature, solid electrolyte Young’s modulus and external stress on dendrite growth and their acting principles are discussed and analyzed. The results show that under the conditions of high temperature, high solid electrolyte Young’s modulus and external stress, the growth of lithium dendrites is slow, the number of long dendrites is small, and the electrodeposition is more uniform. In addition, the effects of Young’s modulus of solid electrolyte and ambient temperature on the growth of lithium dendrites in a common range are compared with each other. It is found that the inhibition effect of changing Young’s modulus of solid electrolyte on the maximum length of lithium dendrites is 19% higher than that caused by the change of ambient temperature.
{"title":"Mechanical stress-thermodynamic phase-field simulation of lithium dendrite growth in solid electrolyte battery","authors":"None Geng Xiao-Bin, None Li Ding-Gen, None Xu Bo","doi":"10.7498/aps.72.20230824","DOIUrl":"https://doi.org/10.7498/aps.72.20230824","url":null,"abstract":"Growth of lithium dendrites in solid state batteries is an important factor that disturbs their commercial applications. The growth of lithium dendrites at the interface of lithium metal anode will not only lead to the decrease of battery energy efficiency, but also cause combustion, explosion and other safety problems. In order to explore the factors and methods that inhibit the growth of lithium dendrites, the phase-field theory is used to simulate the growth of lithium dendrites in polymer solid electrolyte batteries, and a phase-field model of lithium dendrite growth coupled with mechanical stress and thermal field is established. The effects of key physical factors such as ambient temperature, solid electrolyte Young’s modulus and external stress on dendrite growth and their acting principles are discussed and analyzed. The results show that under the conditions of high temperature, high solid electrolyte Young’s modulus and external stress, the growth of lithium dendrites is slow, the number of long dendrites is small, and the electrodeposition is more uniform. In addition, the effects of Young’s modulus of solid electrolyte and ambient temperature on the growth of lithium dendrites in a common range are compared with each other. It is found that the inhibition effect of changing Young’s modulus of solid electrolyte on the maximum length of lithium dendrites is 19% higher than that caused by the change of ambient temperature.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135496014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liquid iron is the major component of planetary cores. Its structure and dynamics under high pressure and temperature is of great significance in studying geophysics and planetary science. However, for experimental techniques, it is still difficult to generate and probe such a state of matter under extreme conditions, while for theoretical method like molecular dynamics simulation, the reliable estimation of dynamic properties requires both large simulation size and ab initio accuracy, resulting in unaffordable computational costs for traditional method. Owing to the technical limitation, the understanding of such matters remains limited. In this work, combining molecular dynamics simulation, we establish a neural network potential energy surface model to study the static and dynamic properties of liquid iron at its extreme thermodynamic state close to core-mantle boundary. The implementation of deep neural network extends the simulation scales from one hundred atoms to millions of atoms within quantum accuracy. The estimated static and dynamic structure factor show good consistency with all available X-ray diffraction and inelastic X-ray scattering experimental observations, while the empirical potential based on embedding-atom-method fails to give a unified description of liquid iron across a wide range of thermodynamic conditions. We also demonstrate that the transport property like diffusion coefficient exhibits a strong size effect, which requires more than at least ten thousands of atoms to give a converged value. Our results show that the combination of deep learning technology and molecular modelling provides a way to describe matter realistically under extreme conditions.
{"title":"Large scale and quantum accurate molecular dynamics simulation: liquid iron under extreme condition","authors":"Qi-Yu Zeng, Bo Chen, Dong-Dong Kang, Jia-Yu Dai","doi":"10.7498/aps.72.20231258","DOIUrl":"https://doi.org/10.7498/aps.72.20231258","url":null,"abstract":"Liquid iron is the major component of planetary cores. Its structure and dynamics under high pressure and temperature is of great significance in studying geophysics and planetary science. However, for experimental techniques, it is still difficult to generate and probe such a state of matter under extreme conditions, while for theoretical method like molecular dynamics simulation, the reliable estimation of dynamic properties requires both large simulation size and <i>ab initio</i> accuracy, resulting in unaffordable computational costs for traditional method. Owing to the technical limitation, the understanding of such matters remains limited. In this work, combining molecular dynamics simulation, we establish a neural network potential energy surface model to study the static and dynamic properties of liquid iron at its extreme thermodynamic state close to core-mantle boundary. The implementation of deep neural network extends the simulation scales from one hundred atoms to millions of atoms within quantum accuracy. The estimated static and dynamic structure factor show good consistency with all available X-ray diffraction and inelastic X-ray scattering experimental observations, while the empirical potential based on embedding-atom-method fails to give a unified description of liquid iron across a wide range of thermodynamic conditions. We also demonstrate that the transport property like diffusion coefficient exhibits a strong size effect, which requires more than at least ten thousands of atoms to give a converged value. Our results show that the combination of deep learning technology and molecular modelling provides a way to describe matter realistically under extreme conditions.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135501946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The competition and cooperation between the itinerancy behavior and localization behavior of electrons in correlated quantum materials, known as Mott physics, is the physical mechanism behind the diverse states of many quantum materials. This article reviews the manifestation of Mott physics in various quantum materials and establishes it as one of the main themes of quantum materials. Finding and understanding its ever-changing ways of manifestation is one of the central tasks of experimental research on condensed matter physics.Specifically, the filling-control route of Mott transition is illustrated by exampling the surface K-dosed Sr2IrO4, which exhibits d-wave gap, pseudogap behavior in underdoped regime, and phase separation with inhomogeneous electronic state distribution. All of these show strong resemblances to the doped cuprate superconductors, another prototypical filling-control type of Mott transition case. On the other hand, the bandwidth-control route of Mott transition could be found in NiS2–xSex, where its bandwidth continuously decreases with Se concentration decreasing, until it becomes an insulator. In addition, the essence of various ways of doping in iron-based superconductors is to change their bandwidths. The superconductivity shows up at intermediate bandwidth with moderate correlations, and it diminishes when the bandwidth is large and the electron correlations are weak. For heavily electron-doped iron-selenides, there is even a Mott insulator phase with strong correlations.For carbon based materials, the phase transition between the antiferromagnetic insulator and superconducting state of A15 Cs3C60 as the volume of fullerene anions decreases could be understood in terms of a bandwidth-control Mott transition; the insulator-superconductor transition discovered in electrically gated twisted-angle bilayer graphene could be understood as a filling-control Mott transition.For f electron systems, the interplay between itinerancy and localization dominates the heavy fermion behavior and their ground states. The behaviors of the f electrons are demonstrated by using the angle-resolved photoemission data of CeCoIn5, whose f electron band becomes more coherent with temperature decreasing, and the c-f hybridization is thus enhanced and the band mass of conduction band continuously increases. The c-f hybridization behaviors of CeCoIn5, CeIrIn5, and CeRhIn5 are compared with each other, and the differences in hybridization strength put their ground states into different regimes of the Doniach phase diagram. Similarly, the Skutterudites 4f2 Kondo lattice system PrOs4Sb12 and its sibling 4f1 system CeOs4Sb12 also have different ground states due to a slight difference in their c-f hybridization strengths.
{"title":"Mott physics — one of main themes in quantum materials","authors":"Dong-Lai Feng","doi":"10.7498/aps.72.20231508","DOIUrl":"https://doi.org/10.7498/aps.72.20231508","url":null,"abstract":"<sec>The competition and cooperation between the itinerancy behavior and localization behavior of electrons in correlated quantum materials, known as Mott physics, is the physical mechanism behind the diverse states of many quantum materials. This article reviews the manifestation of Mott physics in various quantum materials and establishes it as one of the main themes of quantum materials. Finding and understanding its ever-changing ways of manifestation is one of the central tasks of experimental research on condensed matter physics.</sec><sec>Specifically, the filling-control route of Mott transition is illustrated by exampling the surface K-dosed Sr<sub>2</sub>IrO<sub>4</sub>, which exhibits d-wave gap, pseudogap behavior in underdoped regime, and phase separation with inhomogeneous electronic state distribution. All of these show strong resemblances to the doped cuprate superconductors, another prototypical filling-control type of Mott transition case. On the other hand, the bandwidth-control route of Mott transition could be found in NiS<sub>2–<i>x</i></sub>Se<sub><i>x</i></sub>, where its bandwidth continuously decreases with Se concentration decreasing, until it becomes an insulator. In addition, the essence of various ways of doping in iron-based superconductors is to change their bandwidths. The superconductivity shows up at intermediate bandwidth with moderate correlations, and it diminishes when the bandwidth is large and the electron correlations are weak. For heavily electron-doped iron-selenides, there is even a Mott insulator phase with strong correlations.</sec><sec>For carbon based materials, the phase transition between the antiferromagnetic insulator and superconducting state of A15 Cs<sub>3</sub>C<sub>60</sub> as the volume of fullerene anions decreases could be understood in terms of a bandwidth-control Mott transition; the insulator-superconductor transition discovered in electrically gated twisted-angle bilayer graphene could be understood as a filling-control Mott transition.</sec><sec>For f electron systems, the interplay between itinerancy and localization dominates the heavy fermion behavior and their ground states. The behaviors of the f electrons are demonstrated by using the angle-resolved photoemission data of CeCoIn<sub>5</sub>, whose f electron band becomes more coherent with temperature decreasing, and the c-f hybridization is thus enhanced and the band mass of conduction band continuously increases. The c-f hybridization behaviors of CeCoIn<sub>5,</sub> CeIrIn<sub>5</sub>, and CeRhIn<sub>5</sub> are compared with each other, and the differences in hybridization strength put their ground states into different regimes of the Doniach phase diagram. Similarly, the Skutterudites 4f<sup>2</sup> Kondo lattice system PrOs<sub>4</sub>Sb<sub>12</sub> and its sibling 4f<sup>1</sup> system CeOs<sub>4</sub>Sb<sub>12</sub> also have different ground states due to a slight difference in their c-f hybridization strengths.</sec","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135659105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Floquet engineering based on the strong light-matter interaction is expected to drive quantum materials into nonequilibrium states on an ultrafast timescale, thereby engineering their electronic structure and physical properties, and achieving novel physical effects which has no counterpart in equilibrium states. In recent years, Floquet engineering has attracted a lot of research interest, and there have been numerous rich theoretical predictions. In addition, important experimental research progress has also been made in several representative materials such as topological insulators, graphene, and black phosphorus. Here, we briefly introduce the important theoretical and experimental progress in this field, and prospects the research future, experimental challenges, and development directions.
{"title":"Floquet engineering in quantum materials","authors":"None Changhua Bao, None Benshu Fan, None Peizhe Tang, None Wenhui Duan, None Shuyun Zhou","doi":"10.7498/aps.72.20231423","DOIUrl":"https://doi.org/10.7498/aps.72.20231423","url":null,"abstract":"Floquet engineering based on the strong light-matter interaction is expected to drive quantum materials into nonequilibrium states on an ultrafast timescale, thereby engineering their electronic structure and physical properties, and achieving novel physical effects which has no counterpart in equilibrium states. In recent years, Floquet engineering has attracted a lot of research interest, and there have been numerous rich theoretical predictions. In addition, important experimental research progress has also been made in several representative materials such as topological insulators, graphene, and black phosphorus. Here, we briefly introduce the important theoretical and experimental progress in this field, and prospects the research future, experimental challenges, and development directions.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135758464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fundamental concepts of phases and phase transitions constitute the cornerstone of our understanding of the physical universe. The historical development of the phase transition theory from Landau's spontaneous symmetry breaking paradigm to modern topological phase transition theories represents a major milestone in the evolution of numerous scientific disciplines. From the perspective of emergent philosophy, the interplay of topological excitations leads to enriched physical phenomena. One prominent prototype is the Berezinskii-Kosterlitz-Thouless (BKT) phase transition, where unbinding of integer vortices occurs in the absence of spontaneous breaking of continuous U(1) symmetry. Using the state-of-the-art tensor network methods, we express the partition function of the two-dimensional XY-related system in terms of a product of one-dimensional transfer operators. From the singularities of the entanglement entropy of the one-dimensional transfer operator, we accurately determine the complete phase diagram. This method provides new insights into the emergent phenomenon driven by topological excitations, and sheds new light on future studies of 2D systems with continuous symmetries.
{"title":"Thermodynamic phase transition driven by topological excitations and their tensor network approach","authors":"None Song Feng-Feng, None Zhang Guang-Ming","doi":"10.7498/aps.72.20231152","DOIUrl":"https://doi.org/10.7498/aps.72.20231152","url":null,"abstract":"The fundamental concepts of phases and phase transitions constitute the cornerstone of our understanding of the physical universe. The historical development of the phase transition theory from Landau's spontaneous symmetry breaking paradigm to modern topological phase transition theories represents a major milestone in the evolution of numerous scientific disciplines. From the perspective of emergent philosophy, the interplay of topological excitations leads to enriched physical phenomena. One prominent prototype is the Berezinskii-Kosterlitz-Thouless (BKT) phase transition, where unbinding of integer vortices occurs in the absence of spontaneous breaking of continuous <i>U</i>(1) symmetry. Using the state-of-the-art tensor network methods, we express the partition function of the two-dimensional <i>XY</i>-related system in terms of a product of one-dimensional transfer operators. From the singularities of the entanglement entropy of the one-dimensional transfer operator, we accurately determine the complete phase diagram. This method provides new insights into the emergent phenomenon driven by topological excitations, and sheds new light on future studies of 2D systems with continuous symmetries.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135400644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semi-quantum key distribution allows a full quantum user Alice and a classical user Bob to share a pair of security keys guaranteed by physical principles. Semi-quantum key distribution is proposed while verifying its robustness. Subsequently, its unconditional security of semi quantum key distribution system is verified theoretically. In 2021, the feasibility of semi quantum key distribution system based on mirror protocol was verified experimentally. However, the feasibility experimental system still uses the laser pulse with strong attenuation. It has been proved in the literature that the semi-quantum key distribution system still encounters the risk of secret key leakage under photon number splitting attack. Therefore, the actual security of key distribution can be further reasonably evaluated by introducing the temptation state and conducting the finite-key analysis in the key distribution process. In this work, for the model of adding one-decoy state only to Alice at the sending based on a four state semi-quantum key distribution system, the length of the security key in the case of finite-key is analyzed by using Hoeffding inequality, and then the formula of the security key rate is obtained. It is found in the numerical simulation that when the sample size is begin{document}$ {10}^{5} $end{document}, the security key rate of begin{document}$ {10}^{-4} $end{document}, which is close to the security key rate of the asymptotic limits, can be obtained in the case of close range, It is very important for the practical application of semi quantum key distribution system.
Semi-quantum key distribution allows a full quantum user Alice and a classical user Bob to share a pair of security keys guaranteed by physical principles. Semi-quantum key distribution is proposed while verifying its robustness. Subsequently, its unconditional security of semi quantum key distribution system is verified theoretically. In 2021, the feasibility of semi quantum key distribution system based on mirror protocol was verified experimentally. However, the feasibility experimental system still uses the laser pulse with strong attenuation. It has been proved in the literature that the semi-quantum key distribution system still encounters the risk of secret key leakage under photon number splitting attack. Therefore, the actual security of key distribution can be further reasonably evaluated by introducing the temptation state and conducting the finite-key analysis in the key distribution process. In this work, for the model of adding one-decoy state only to Alice at the sending based on a four state semi-quantum key distribution system, the length of the security key in the case of finite-key is analyzed by using Hoeffding inequality, and then the formula of the security key rate is obtained. It is found in the numerical simulation that when the sample size is <inline-formula><tex-math id="M3">begin{document}$ {10}^{5} $end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="22-20230849_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="22-20230849_M3.png"/></alternatives></inline-formula>, the security key rate of <inline-formula><tex-math id="M4">begin{document}$ {10}^{-4} $end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="22-20230849_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="22-20230849_M4.png"/></alternatives></inline-formula>, which is close to the security key rate of the asymptotic limits, can be obtained in the case of close range, It is very important for the practical application of semi quantum key distribution system.
{"title":"Finite-key analysis of decoy model Semi-quantum key distribution based on four-state protocol","authors":"None Zhan Shao-Kang, None Wang Jin-Dong, None Dong Shuang, None Huang Si-Ying, None Hou Qing-Cheng, None Mo Nai-Da, None Mi Shang, None Xiang Li-Bing, None Zhao Tian-Ming, None Yu Ya-Fei, None Wei Zheng-Jun, None Zhang Zhi-Ming","doi":"10.7498/aps.72.20230849","DOIUrl":"https://doi.org/10.7498/aps.72.20230849","url":null,"abstract":"Semi-quantum key distribution allows a full quantum user Alice and a classical user Bob to share a pair of security keys guaranteed by physical principles. Semi-quantum key distribution is proposed while verifying its robustness. Subsequently, its unconditional security of semi quantum key distribution system is verified theoretically. In 2021, the feasibility of semi quantum key distribution system based on mirror protocol was verified experimentally. However, the feasibility experimental system still uses the laser pulse with strong attenuation. It has been proved in the literature that the semi-quantum key distribution system still encounters the risk of secret key leakage under photon number splitting attack. Therefore, the actual security of key distribution can be further reasonably evaluated by introducing the temptation state and conducting the finite-key analysis in the key distribution process. In this work, for the model of adding one-decoy state only to Alice at the sending based on a four state semi-quantum key distribution system, the length of the security key in the case of finite-key is analyzed by using Hoeffding inequality, and then the formula of the security key rate is obtained. It is found in the numerical simulation that when the sample size is <inline-formula><tex-math id=\"M3\">begin{document}$ {10}^{5} $end{document}</tex-math><alternatives><graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"22-20230849_M3.jpg\"/><graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"22-20230849_M3.png\"/></alternatives></inline-formula>, the security key rate of <inline-formula><tex-math id=\"M4\">begin{document}$ {10}^{-4} $end{document}</tex-math><alternatives><graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"22-20230849_M4.jpg\"/><graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"22-20230849_M4.png\"/></alternatives></inline-formula>, which is close to the security key rate of the asymptotic limits, can be obtained in the case of close range, It is very important for the practical application of semi quantum key distribution system.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135401836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To understand the effects of given radial electric field on ion-temperature gradient driven mode (ITG) stability in tokamak plasmas, the eigenmode equation for ITG including the poloidal rotation and density modulation associated with radial electric field is derived using nonlinear gyrokinetic theory. The equation is solved for eigenfrequency, growth rate and parallel mode structure of ITG both in short- and long-wavelength limit with energetic-particle-induced geodesic acoustic mode (EGAM) as a specific form. The eigenmode equation is not only solved analytically, but also solved numerically to validate the analytic solutions. It is found that, radial electric field induced poloidal rotation can significantly stabilize ITG, while the density perturbation of the radial electric field may slightly distort the ITG parallel mode structure, but has little effect on ITG stability. The result is consistent with common picture of turbulence suppression by poloidal shear flow. The general model is also applicable to the investigation of the indirect interaction of ITG and energetic particle driven Alfvén instabilities via zonal structures generation, by means of introducing poloidal rotation and density modulation associated with zonal structures spontaneously excited by Alfvén instabilities. The indirect channel is supplement to the direct interaction of microturbulences and energetic particle driven Alfvén instabilities.
{"title":"Effects of radial electric field on ion-temperature gradient driven mode stability","authors":"None Chen Ning-Fei, None Wei Guang-Yu, None Qiu Zhi-Yong","doi":"10.7498/aps.72.20230798","DOIUrl":"https://doi.org/10.7498/aps.72.20230798","url":null,"abstract":"To understand the effects of given radial electric field on ion-temperature gradient driven mode (ITG) stability in tokamak plasmas, the eigenmode equation for ITG including the poloidal rotation and density modulation associated with radial electric field is derived using nonlinear gyrokinetic theory. The equation is solved for eigenfrequency, growth rate and parallel mode structure of ITG both in short- and long-wavelength limit with energetic-particle-induced geodesic acoustic mode (EGAM) as a specific form. The eigenmode equation is not only solved analytically, but also solved numerically to validate the analytic solutions. It is found that, radial electric field induced poloidal rotation can significantly stabilize ITG, while the density perturbation of the radial electric field may slightly distort the ITG parallel mode structure, but has little effect on ITG stability. The result is consistent with common picture of turbulence suppression by poloidal shear flow. The general model is also applicable to the investigation of the indirect interaction of ITG and energetic particle driven Alfvén instabilities via zonal structures generation, by means of introducing poloidal rotation and density modulation associated with zonal structures spontaneously excited by Alfvén instabilities. The indirect channel is supplement to the direct interaction of microturbulences and energetic particle driven Alfvén instabilities.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136259598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Metal-matrix diamond composites have been extensively applied and studied, but vacancies, doping, and other defects caused by the pretreatment of the diamond surface significantly impact the interface performance between the metal base and diamond. Although techniques like transmission electron microscopy and spectroscopy analysis have been utilized for defect detection, they present certain limitations. Calculating the positron annihilation lifetime in diamond provides an accurate assessment of interface defects in the diamond. This study uses first-principles calculation methods, adopting various positron annihilation algorithms and enhancement factors, to compute the positron annihilation lifetime in ideal diamond crystals, single vacancies, and when doped with B, Cr, Mo, Ti, W, and Zr. The results, obtained using local density functional in combination with Boronski & Nieminen algorithms and RPA restriction as annihilation enhancement factors, indicate that the computed positron annihilation lifetime of diamond is 119.87ps, aligning closely with literature experimental results. Furthermore, after doping B, Cr, Mo, Ti, W, and Zr atoms in diamond (doping concentration of 1.6at%), the positron annihilation lifetime changed from a single vacancy 119.87ps to 148.57, 156.82, 119.05, 116.5, 117.62, and 115.74ps respectively. This implies that defects due to doped atoms in diamond alter its positron annihilation lifetime, with the impact varying according to the different atoms doped. Based on the calculated electron density in diamond vacancies and doped atom areas, it was discovered that doping atoms did not cause severe distortion in the diamond lattice. However, after doping B and Cr atoms, a significant increase in positron annihilation lifetime was noted. The primary reason is the relatively low positron affinity of B and Cr atoms, resulting in an extended positron residence time in the vacancy, thereby increasing the annihilation lifetime. Overall, vacancies and doped atom defects in diamond will cause changes in its positron annihilation lifetime, and the above conclusions provide crucial theoretical references for detecting and identifying interface defects caused by doping treatment on the diamond surface during the preparation of metal-matrix diamond composites.
{"title":"Calculation of Positron Annihilation Lifetime in Diamond Doped with B, Cr, Mo, Ti, W, Zr","authors":"None Zhao Yong-Sheng, None 阎峰云, None Yan Feng-Yun","doi":"10.7498/aps.73.20231269","DOIUrl":"https://doi.org/10.7498/aps.73.20231269","url":null,"abstract":"Metal-matrix diamond composites have been extensively applied and studied, but vacancies, doping, and other defects caused by the pretreatment of the diamond surface significantly impact the interface performance between the metal base and diamond. Although techniques like transmission electron microscopy and spectroscopy analysis have been utilized for defect detection, they present certain limitations. Calculating the positron annihilation lifetime in diamond provides an accurate assessment of interface defects in the diamond. This study uses first-principles calculation methods, adopting various positron annihilation algorithms and enhancement factors, to compute the positron annihilation lifetime in ideal diamond crystals, single vacancies, and when doped with B, Cr, Mo, Ti, W, and Zr. The results, obtained using local density functional in combination with Boronski & Nieminen algorithms and RPA restriction as annihilation enhancement factors, indicate that the computed positron annihilation lifetime of diamond is 119.87ps, aligning closely with literature experimental results. Furthermore, after doping B, Cr, Mo, Ti, W, and Zr atoms in diamond (doping concentration of 1.6at%), the positron annihilation lifetime changed from a single vacancy 119.87ps to 148.57, 156.82, 119.05, 116.5, 117.62, and 115.74ps respectively. This implies that defects due to doped atoms in diamond alter its positron annihilation lifetime, with the impact varying according to the different atoms doped. Based on the calculated electron density in diamond vacancies and doped atom areas, it was discovered that doping atoms did not cause severe distortion in the diamond lattice. However, after doping B and Cr atoms, a significant increase in positron annihilation lifetime was noted. The primary reason is the relatively low positron affinity of B and Cr atoms, resulting in an extended positron residence time in the vacancy, thereby increasing the annihilation lifetime. Overall, vacancies and doped atom defects in diamond will cause changes in its positron annihilation lifetime, and the above conclusions provide crucial theoretical references for detecting and identifying interface defects caused by doping treatment on the diamond surface during the preparation of metal-matrix diamond composites.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136202185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
None Yang Shuai, None Tang Zebo, None Yang Chi, None Zha Wangmei
The Lorentz-boosted electromagnetic fields surrounding relativistic heavy ions with large charges can be treated as a flux of linearly polarized quasireal photons, which can interact via the photon-photon scattering to produce lepton antilepton pairs. Those photon-photon interactions can happen even in heavy-ion collisions with hadronic overlap, making an opportunity to probe the electromagnetic properties of the produced deconfined quark-gluon plasma. In this paper, we review the recent experimental progress of the impact parameter dependent photon-photon interactions in heavy-ion collisions, and discuss their essential role in probing the possible electromagnetic properties of quark-gluon plasma produced in hadronic heavy-ion collisions.
{"title":"Impact parameter dependence of photon-photon interactions in relativistic heavy-ion collisions","authors":"None Yang Shuai, None Tang Zebo, None Yang Chi, None Zha Wangmei","doi":"10.7498/aps.72.20230948","DOIUrl":"https://doi.org/10.7498/aps.72.20230948","url":null,"abstract":"The Lorentz-boosted electromagnetic fields surrounding relativistic heavy ions with large charges can be treated as a flux of linearly polarized quasireal photons, which can interact via the photon-photon scattering to produce lepton antilepton pairs. Those photon-photon interactions can happen even in heavy-ion collisions with hadronic overlap, making an opportunity to probe the electromagnetic properties of the produced deconfined quark-gluon plasma. In this paper, we review the recent experimental progress of the impact parameter dependent photon-photon interactions in heavy-ion collisions, and discuss their essential role in probing the possible electromagnetic properties of quark-gluon plasma produced in hadronic heavy-ion collisions.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136203262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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