Di Shu-Hong, Zhang Yang, Yang Hui-Jing, Cui Nai-Zhong, Li Yan-Kun, Liu Hui-Yuan, Li Ling-Li, Shi Feng-Liang, Jia Yu-Xuan
Because of the difficulty in measuring the cluster isotope displacement and identifying its causes, the resonance dissociation spectra, the moment shift and Zeeman energy shift of isotope cluster 87,85Rbn(n=1,2, 3,..., 13) are obtained by the combination of optical magnetic resonance and thermal dissociation techniques in this study. The quantitative calculation is carried out based on the conceptual model of the giant atom, and the results are in strict agreement with the measured results, which shows that rubidium clusters can be analyzed as giant-like atoms. Furthermore, 5s electron shell level structure of the rubidium cluster 87,85Rbn(n=1,2, 3,..., 92) is calculated using Zeeman level interval model. It is found that the main order and step distance of the 5s electron shell structure are similar to those of 3s single electron shell structure of sodium cluster in spherical symmetric. It is confirmed that the structure of the 5s electron shell of the rubidium cluster is determined by the largest energy gap of total Zeeman levels and the characteristic peaks of odd and even alternating and anomalous magnetic moments of special numbers such as n=2 are caused by the intrinsic properties of electrons and molecular structures. It is also found that 87Rbn and 85Rbn level shell structure is strictly consistent with the ratio of 3/2 magnitude relationship, and there are abnormal differences in spectral center frequency and broadening, which may be directly related to the 85,87Rb nuclide on the closed surface of the core-shell.
{"title":"Quantitative study on isotope effect of rubidium clusters","authors":"Di Shu-Hong, Zhang Yang, Yang Hui-Jing, Cui Nai-Zhong, Li Yan-Kun, Liu Hui-Yuan, Li Ling-Li, Shi Feng-Liang, Jia Yu-Xuan","doi":"10.7498/aps.72.20230778","DOIUrl":"https://doi.org/10.7498/aps.72.20230778","url":null,"abstract":"Because of the difficulty in measuring the cluster isotope displacement and identifying its causes, the resonance dissociation spectra, the moment shift and Zeeman energy shift of isotope cluster 87,85Rbn(n=1,2, 3,..., 13) are obtained by the combination of optical magnetic resonance and thermal dissociation techniques in this study. The quantitative calculation is carried out based on the conceptual model of the giant atom, and the results are in strict agreement with the measured results, which shows that rubidium clusters can be analyzed as giant-like atoms. Furthermore, 5s electron shell level structure of the rubidium cluster 87,85Rbn(n=1,2, 3,..., 92) is calculated using Zeeman level interval model. It is found that the main order and step distance of the 5s electron shell structure are similar to those of 3s single electron shell structure of sodium cluster in spherical symmetric. It is confirmed that the structure of the 5s electron shell of the rubidium cluster is determined by the largest energy gap of total Zeeman levels and the characteristic peaks of odd and even alternating and anomalous magnetic moments of special numbers such as n=2 are caused by the intrinsic properties of electrons and molecular structures. It is also found that 87Rbn and 85Rbn level shell structure is strictly consistent with the ratio of 3/2 magnitude relationship, and there are abnormal differences in spectral center frequency and broadening, which may be directly related to the 85,87Rb nuclide on the closed surface of the core-shell.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"26 9","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72409684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wang Li-na, Zhao Xing-Yu, Shang Jie-Ying, Zhou Heng-Wei
Monohydroxy alcohol has a Debye relaxation process that other liquids usually do not have, and with the development of research, some new phenomena and new problems related to the process have been gradually discovered, deepening the understanding of material structure and dynamics. In order to further investigate the dynamics of Debye relaxation processes and the influence of molecular constitutions on them, the Debye processes of three primary alcohols without branched chains or side groups are studied by dielectric spectroscopy method, and some important information of the processes are revealed. A number of dynamic parameters of Debye relaxation in n-propanol, n-butanol and n-octanol almost all increase linearly with the rising number of carbon atoms in the molecules, which include the characteristic temperature, the reciprocal of Vogel-Fulcher-Tammann (VFT) temperature and the strength parameter of Debye processes as well as the activation energy and the logarithm of the intrinsic vibration frequency of relaxation units under high temperature limit. However, the values of VFT temperatures change little and have consistency, illustrating that the relaxation units of Debye processes in these three monohydroxy alcohols should be the same and further verifying the view that the Debye relaxation originates from the hydroxyl groups in hydrogen bonded molecular chains. Comparing Boiling temperatures and melting temperatures of those samples with the evolution of the above activation energy, it is shown that there is a positive correlation between the interaction among hydrogen bonds and the whole one among molecules. In addition, combined the information of the strength parameter with relevant theories, a possible perspective is gained for further investigation of liquid fragility. The comparison of those three samples with ethanol displays that the degree of separation of Debye relaxation and α relaxation is influenced by the molecular chain length, which could provide a breakthrough point to explore Debye relaxation. These results in this paper will promote further understanding and research of Debye relaxation in monohydroxy alcohols, and also provide experimental information for relevant theories.
{"title":"Measurement and Analysis of Debye Relaxation dynamics of n-propanol, n-butanol and n-octanol","authors":"Wang Li-na, Zhao Xing-Yu, Shang Jie-Ying, Zhou Heng-Wei","doi":"10.7498/aps.72.20221856","DOIUrl":"https://doi.org/10.7498/aps.72.20221856","url":null,"abstract":"Monohydroxy alcohol has a Debye relaxation process that other liquids usually do not have, and with the development of research, some new phenomena and new problems related to the process have been gradually discovered, deepening the understanding of material structure and dynamics. In order to further investigate the dynamics of Debye relaxation processes and the influence of molecular constitutions on them, the Debye processes of three primary alcohols without branched chains or side groups are studied by dielectric spectroscopy method, and some important information of the processes are revealed. A number of dynamic parameters of Debye relaxation in n-propanol, n-butanol and n-octanol almost all increase linearly with the rising number of carbon atoms in the molecules, which include the characteristic temperature, the reciprocal of Vogel-Fulcher-Tammann (VFT) temperature and the strength parameter of Debye processes as well as the activation energy and the logarithm of the intrinsic vibration frequency of relaxation units under high temperature limit. However, the values of VFT temperatures change little and have consistency, illustrating that the relaxation units of Debye processes in these three monohydroxy alcohols should be the same and further verifying the view that the Debye relaxation originates from the hydroxyl groups in hydrogen bonded molecular chains. Comparing Boiling temperatures and melting temperatures of those samples with the evolution of the above activation energy, it is shown that there is a positive correlation between the interaction among hydrogen bonds and the whole one among molecules. In addition, combined the information of the strength parameter with relevant theories, a possible perspective is gained for further investigation of liquid fragility. The comparison of those three samples with ethanol displays that the degree of separation of Debye relaxation and α relaxation is influenced by the molecular chain length, which could provide a breakthrough point to explore Debye relaxation. These results in this paper will promote further understanding and research of Debye relaxation in monohydroxy alcohols, and also provide experimental information for relevant theories.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"50 6 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72830832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the continuous development of CMOS technology, the feature size of MOSFETs is continuously shrunk, the short channel effects become more and more serious, which makes the static power consumption increase and now the static power consumption becomes the main source of the power consumption of the integrated circuits. At present, the performance of CMOS binary logic processors is nearly reaching the bottleneck; therefore the study of ternary logic becomes a research hotspot to promote the development of high performance and low power integrated circuits. Compared with binary logic, ternary logic possesses stronger data expression ability, which can not only improve the data density, but also reduce the circuit power consumption and the system complexity. However, using binary devices to build ternary logic circuits requires a large number of components, and even requires the passive components, which cannot exploit the advantages of ternary logic. The other method of implementing ternary logic is through the utilization of innovative two-dimensional materials. This method requires a small number of components and obviates the need for passive components, but it faces the problem that the fabrication process is not mature and can’t be mass-produced. To solve these issues, this paper combines the tunneling and the drift diffusion mechanism, proposed tunneling metal-oxide-semiconductor field-effect transistor (TMOSFET) which three-state characteristics make it highly suitable for ternary logic design. Compared with other ternary logic schemes, the ternary inverter based on TMOSFET has the same circuit structure with binary inverter, which can simplify the circuit design. In this paper, the operational mechanism of this ternary inverter is studied, and the condition of three-state output of inverter is analyzed. It is found that when the operating voltage VDD and the device turning voltage Vturn satisfy VDD/Vturn≈1.4, the input voltage ranges of the three output states are equivalent. In addition, the impact of TMOSFET transfer characteristic on this ternary inverter is also analyzed. This has certain reference significance for the future design and research of ternary logic circuits.
{"title":"A Novel TMOSFET Ternary Inverter Based on Hybrid Conduction Mechanism","authors":"Ma Xin, Lu Bin, Dong Linpeng, MiaoYuanhao","doi":"10.7498/aps.72.20230819","DOIUrl":"https://doi.org/10.7498/aps.72.20230819","url":null,"abstract":"With the continuous development of CMOS technology, the feature size of MOSFETs is continuously shrunk, the short channel effects become more and more serious, which makes the static power consumption increase and now the static power consumption becomes the main source of the power consumption of the integrated circuits. At present, the performance of CMOS binary logic processors is nearly reaching the bottleneck; therefore the study of ternary logic becomes a research hotspot to promote the development of high performance and low power integrated circuits. Compared with binary logic, ternary logic possesses stronger data expression ability, which can not only improve the data density, but also reduce the circuit power consumption and the system complexity. However, using binary devices to build ternary logic circuits requires a large number of components, and even requires the passive components, which cannot exploit the advantages of ternary logic. The other method of implementing ternary logic is through the utilization of innovative two-dimensional materials. This method requires a small number of components and obviates the need for passive components, but it faces the problem that the fabrication process is not mature and can’t be mass-produced. To solve these issues, this paper combines the tunneling and the drift diffusion mechanism, proposed tunneling metal-oxide-semiconductor field-effect transistor (TMOSFET) which three-state characteristics make it highly suitable for ternary logic design. Compared with other ternary logic schemes, the ternary inverter based on TMOSFET has the same circuit structure with binary inverter, which can simplify the circuit design. In this paper, the operational mechanism of this ternary inverter is studied, and the condition of three-state output of inverter is analyzed. It is found that when the operating voltage VDD and the device turning voltage Vturn satisfy VDD/Vturn≈1.4, the input voltage ranges of the three output states are equivalent. In addition, the impact of TMOSFET transfer characteristic on this ternary inverter is also analyzed. This has certain reference significance for the future design and research of ternary logic circuits.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"14 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72836894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The optimal selection of parameters in practical quantum key distribution can greatly improve the key generation rate and maximum transmission distance of the system. Due to the high cost of global search algorithm, local search algorithm is widely used. However, there are two vulnerabilities in local search algorithm, one is that the solution obtained is not always the global optimal solution, the other is that the effectiveness of the algorithm is greatly dependent on the choice of initial value. It is different from the previous article that this paper uses the Monte Carlo method to prove whether the key generation rate function is convex, and also simulates and analyzes the projection of key generation rate function on each dimension of the parameter. In order to eliminate the effect of the initial value, this paper proposes the particle swarm local search optimization algorithm which is combining particle swarm optimization algorithm and local search algorithm. The first step is using the particle swarm optimization to find a valid parameter which leads to nonzero key generation rate, the second step is using the parameter as the initial value of local search algorithm to derive the global optimal solution. Then, the two algorithms are simulated and compared. The results show that the key generation rate function is non-convex because it does not satisfy the definition of a convex function, however, since the key generation rate function has only one non-zero stagnation point, the LSA algorithm can still obtain the global optimal solution with a proper initial value, when the transmission distance is relatively long, the local search algorithm is invalid because it is difficult to obtain an effective initial value by random value method. Particle swarm optimization algorithm can overcome this shortcoming and improve the maximum transmission distance of the system at the cost of slightly increasing the complexity of the algorithm.
{"title":"Improved parameter optimization method for measurement device independent protocol","authors":"Zhou Jiang-Ping, Zhou Yuan-Yuan, Zhou Xue-Jun","doi":"10.7498/aps.72.20230179","DOIUrl":"https://doi.org/10.7498/aps.72.20230179","url":null,"abstract":"The optimal selection of parameters in practical quantum key distribution can greatly improve the key generation rate and maximum transmission distance of the system. Due to the high cost of global search algorithm, local search algorithm is widely used. However, there are two vulnerabilities in local search algorithm, one is that the solution obtained is not always the global optimal solution, the other is that the effectiveness of the algorithm is greatly dependent on the choice of initial value. It is different from the previous article that this paper uses the Monte Carlo method to prove whether the key generation rate function is convex, and also simulates and analyzes the projection of key generation rate function on each dimension of the parameter. In order to eliminate the effect of the initial value, this paper proposes the particle swarm local search optimization algorithm which is combining particle swarm optimization algorithm and local search algorithm. The first step is using the particle swarm optimization to find a valid parameter which leads to nonzero key generation rate, the second step is using the parameter as the initial value of local search algorithm to derive the global optimal solution. Then, the two algorithms are simulated and compared. The results show that the key generation rate function is non-convex because it does not satisfy the definition of a convex function, however, since the key generation rate function has only one non-zero stagnation point, the LSA algorithm can still obtain the global optimal solution with a proper initial value, when the transmission distance is relatively long, the local search algorithm is invalid because it is difficult to obtain an effective initial value by random value method. Particle swarm optimization algorithm can overcome this shortcoming and improve the maximum transmission distance of the system at the cost of slightly increasing the complexity of the algorithm.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"91 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74644463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mechanism of photon acceleration driven by the near-forward scattering (NFS) in intense laser under-dense plasma interaction has been studied by particle-in-cell (PIC) simulation. This mechanism utilizes tunneling ionization effect to stimulate electron plasma waves when the intense laser pulse propagates in under-dense plasmas. The electron plasma density is inhomogeneous both in longitudinal and transverse direction. In longitudinal direction, a steep ionized electron density front is generated by incident laser ionizing the helium gas. Around the ionization front, the incident laser interacts with electron plasma waves and generates the first kind of NFS waves. The frequency of NFS waves increases compared to the laser frequency. This is the first characteristic peak in the frequency spectrum. In transverse direction, the electron plasma waves have different phase velocities which makes the incident laser pulse undergoes NFS process and upshifts its frequency. This is the second characteristic peak in the frequency spectrum. Due to that the electron density inhomogeneity is much larger than the electron density perturbation of electron plasma wave, the scattering model and dispersion relationships, which are based on perturbation theory like the stimulated Raman scattering, are no longer applicable in this case. Our further study shows that the incident laser, electron density plasma waves and NFS waves still satisfy the energy conservation and momentum conservation which leads to the three-waves matching conditions of NFS process for inhomogeneous electron density. This can explain the appearance of two characteristic peaks in the frequency spectrum and their growth in the wave-vector space. This study has significant reference for the spectrum evolution when the intense laser pulse propagates in under-dense plasmas.
{"title":"The Study of Photon Acceleration Driven by the Near-forward Scattering in the Intense Laser Under-dense Plasma Interaction","authors":"Yue Dong-Ning, Dong Quan-Li, Chen Min, Zhao Yao, Geng Pan-Fei, Yuan Xiao-hui, Sheng Zheng-Ming, Zhang Jie","doi":"10.7498/aps.72.20222014","DOIUrl":"https://doi.org/10.7498/aps.72.20222014","url":null,"abstract":"The mechanism of photon acceleration driven by the near-forward scattering (NFS) in intense laser under-dense plasma interaction has been studied by particle-in-cell (PIC) simulation. This mechanism utilizes tunneling ionization effect to stimulate electron plasma waves when the intense laser pulse propagates in under-dense plasmas. The electron plasma density is inhomogeneous both in longitudinal and transverse direction. In longitudinal direction, a steep ionized electron density front is generated by incident laser ionizing the helium gas. Around the ionization front, the incident laser interacts with electron plasma waves and generates the first kind of NFS waves. The frequency of NFS waves increases compared to the laser frequency. This is the first characteristic peak in the frequency spectrum. In transverse direction, the electron plasma waves have different phase velocities which makes the incident laser pulse undergoes NFS process and upshifts its frequency. This is the second characteristic peak in the frequency spectrum. Due to that the electron density inhomogeneity is much larger than the electron density perturbation of electron plasma wave, the scattering model and dispersion relationships, which are based on perturbation theory like the stimulated Raman scattering, are no longer applicable in this case. Our further study shows that the incident laser, electron density plasma waves and NFS waves still satisfy the energy conservation and momentum conservation which leads to the three-waves matching conditions of NFS process for inhomogeneous electron density. This can explain the appearance of two characteristic peaks in the frequency spectrum and their growth in the wave-vector space. This study has significant reference for the spectrum evolution when the intense laser pulse propagates in under-dense plasmas.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"102 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77563942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cui Sui-Han, Zuo Wei, Huang Jian, Li Xi-Teng, Chen Qiu-Hao, Guo Yu-Xiang, Yang Chao, Wu Zhong-Can, Ma Zheng-Yong, Ricky K Y Fu, Tian Xiu-Bo, Paul K. Chu, Wu Zhong-Zhen
Plasma simulation is important to study the plasma discharge systematically, especially for the anode layer ion source which has the complex geometrical characteristics of the discharge structures. However, owing to the complex solution domain formed by the geometric profile of the anode and cathode, the traditional simulation models show extremely small computational efficiency and poor convergence. This paper presents a separated simulation for the ion source structure and the plasma discharge, respectively, where the cathode geometric parameters (including the size, the shape and the relative position of the inner and outer cathodes) are simplified to two magnetic mirror parameters (the magnetic mirror ratio Rm and the magnetic induction intensity at the center of the magnetic mirror B 0) firstly and a high-efficient particle-in-cell/Monte Carlo collision (PIC/MCC) model is established to improve the computational efficiency and stability of the plasma simulation later. As a result, the convergence time of the plasma simulation is shortened significantly from 1 μs to 0.45 μs, and by which the influences of the geometrical characteristics of the discharge structure on the plasma properties are systematically studied. The simulation results reveal that magnetic mirror with Rm=2.50 and B 0=36 mT can constraint the plasma at the centre zone between the inner and outer cathode. When the discharge center of the plasma is consistent with the magnetic mirror center, the anode layer ion source presents both high density output of ion beam current and significantly reduced cathode etching, suggesting the best balance obtained between the output and cathode etching.
{"title":"High-efficient particle-in-cell/Monte Carlo collision model for complex solution domain and the simulation of anode layer ion source","authors":"Cui Sui-Han, Zuo Wei, Huang Jian, Li Xi-Teng, Chen Qiu-Hao, Guo Yu-Xiang, Yang Chao, Wu Zhong-Can, Ma Zheng-Yong, Ricky K Y Fu, Tian Xiu-Bo, Paul K. Chu, Wu Zhong-Zhen","doi":"10.7498/aps.72.20222394","DOIUrl":"https://doi.org/10.7498/aps.72.20222394","url":null,"abstract":"Plasma simulation is important to study the plasma discharge systematically, especially for the anode layer ion source which has the complex geometrical characteristics of the discharge structures. However, owing to the complex solution domain formed by the geometric profile of the anode and cathode, the traditional simulation models show extremely small computational efficiency and poor convergence. This paper presents a separated simulation for the ion source structure and the plasma discharge, respectively, where the cathode geometric parameters (including the size, the shape and the relative position of the inner and outer cathodes) are simplified to two magnetic mirror parameters (the magnetic mirror ratio Rm and the magnetic induction intensity at the center of the magnetic mirror B 0) firstly and a high-efficient particle-in-cell/Monte Carlo collision (PIC/MCC) model is established to improve the computational efficiency and stability of the plasma simulation later. As a result, the convergence time of the plasma simulation is shortened significantly from 1 μs to 0.45 μs, and by which the influences of the geometrical characteristics of the discharge structure on the plasma properties are systematically studied. The simulation results reveal that magnetic mirror with Rm=2.50 and B 0=36 mT can constraint the plasma at the centre zone between the inner and outer cathode. When the discharge center of the plasma is consistent with the magnetic mirror center, the anode layer ion source presents both high density output of ion beam current and significantly reduced cathode etching, suggesting the best balance obtained between the output and cathode etching.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"33 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77830156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
He Ya-Ping, Chen Ming-Xia, Pan Jie-Feng, Li Dong, Lin Gang-Jun, Huang Xin-Hong
Nanothick semiconductors can grow orderly along a desired direction with the help of modern materials growth technology such as molecular beam epitaxy, which allows researchers to fabricate the so-called layered semiconductor nanostructure (LSN) in experiments. Due to the broken structure inversion symmetry by the layered form in the LSN, the electron spins interact tightly with its momentums, in literatures referred to as the spin-orbit coupling (SOC) effect, which can be modulated well by the interfacial confining electric field or the stain engineering. These significant SOC effects can effectively eliminate the spin degeneracy of the electrons in semiconductor materials, induce the spin splitting phenomenon at the zero magnetic field and generate the electron-spin polarization in the semiconductors. In recent years, the spin-polarized transport for electrons in the LSN has attracted a lot of research interests, thanks to itself scientific importance and potential applications as spin polarized sources in the research field of semiconductor spintronics. Adopting the theoretical analysis combined with the numerical calculation, we investigate the spin-polarized transport induced by the Rashba-type SOC effect for electrons in a single-layered semiconductor nanostructure (SLSN)-InSb. The research objective is to explore the new way for generating and manipulating spin current in semiconductor materials without any magnetic field, and focus on developing new electron-spin filter for semiconductor spintronics device applications. The improved transfer matrix method (ITMM) is exploited to exactly solve Schrödinger equation for an electron in the SLSN-InSb device, which allows us to calculate the spin-dependent transmission coefficient and the spin polarization ratio. Due to a strong Rashba-type SOC, a considerable electron-spin polarization effect appears in the SLSN-InSb device. Because of the effective potential experienced by the electrons in the SLSN-InSb device, the spin polarization ratio is associated with the electron energy and the in-plane wave vector. In particular, the spin polarization ratio can be manipulated effectively by an externally-applied electric field or the semiconductor-layer thickness, owing to the dependence of the effective potential felt by the electrons in the SLSN-InSb device on the electric field or the layer thickness. Therefore, such a SLSN-InSb device can serve as a controllable electron-spin filter as a manipulable spin-polarized source for the research area of semiconductor spintronics.
{"title":"Electron-spin polarization effect in Rashba spin-orbit coupling modulated single-layered semiconductor nanostructure","authors":"He Ya-Ping, Chen Ming-Xia, Pan Jie-Feng, Li Dong, Lin Gang-Jun, Huang Xin-Hong","doi":"10.7498/aps.72.20221381","DOIUrl":"https://doi.org/10.7498/aps.72.20221381","url":null,"abstract":"Nanothick semiconductors can grow orderly along a desired direction with the help of modern materials growth technology such as molecular beam epitaxy, which allows researchers to fabricate the so-called layered semiconductor nanostructure (LSN) in experiments. Due to the broken structure inversion symmetry by the layered form in the LSN, the electron spins interact tightly with its momentums, in literatures referred to as the spin-orbit coupling (SOC) effect, which can be modulated well by the interfacial confining electric field or the stain engineering. These significant SOC effects can effectively eliminate the spin degeneracy of the electrons in semiconductor materials, induce the spin splitting phenomenon at the zero magnetic field and generate the electron-spin polarization in the semiconductors. In recent years, the spin-polarized transport for electrons in the LSN has attracted a lot of research interests, thanks to itself scientific importance and potential applications as spin polarized sources in the research field of semiconductor spintronics. Adopting the theoretical analysis combined with the numerical calculation, we investigate the spin-polarized transport induced by the Rashba-type SOC effect for electrons in a single-layered semiconductor nanostructure (SLSN)-InSb. The research objective is to explore the new way for generating and manipulating spin current in semiconductor materials without any magnetic field, and focus on developing new electron-spin filter for semiconductor spintronics device applications. The improved transfer matrix method (ITMM) is exploited to exactly solve Schrödinger equation for an electron in the SLSN-InSb device, which allows us to calculate the spin-dependent transmission coefficient and the spin polarization ratio. Due to a strong Rashba-type SOC, a considerable electron-spin polarization effect appears in the SLSN-InSb device. Because of the effective potential experienced by the electrons in the SLSN-InSb device, the spin polarization ratio is associated with the electron energy and the in-plane wave vector. In particular, the spin polarization ratio can be manipulated effectively by an externally-applied electric field or the semiconductor-layer thickness, owing to the dependence of the effective potential felt by the electrons in the SLSN-InSb device on the electric field or the layer thickness. Therefore, such a SLSN-InSb device can serve as a controllable electron-spin filter as a manipulable spin-polarized source for the research area of semiconductor spintronics.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77895580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhao Xi, Chen Jing, Peng Teng, Liu Jun-Hong, Wang bo, Chen Xiao-Li, Xiong Zu-Hong
Intersystem crossing (ISC) and reverse ISC (RISC) between singlet and triplet polaron-pair and exciplex states are important spin-mixing processes in exciplex-based organic light-emitting diodes (EB-OLEDs). These two processes usually show normal current dependencies which weaken with increasing the bias-current. This is because the increase in the bias-current is realized by improving the device bias-voltage. When the bias-voltage rises, the electric field within the device enhances, which facilitates the electric-field-induced dissociation of polaron-pair and exciplex states and then reduces their lifetime. That is, less polaron-pair and exciplex states participate in the ISC and RISC processes leading to the reduction of these two processes. Here, magneto-electroluminescence (MEL) is used as a fingerprint probing tool to observe various current-dependent ISC and RISC processes in EB-OLEDs with different charge balances via modifying the device hole-injection layer. Interestingly, current-dependent MEL traces of the unbalanced device display a conversion from normal ISC (1-25 mA) to abnormal ISC (25-200 mA) processes, whereas those of the balanced device show conversions from normal ISC (1-5 mA) to abnormal RISC (10-50 mA) and then to normal RISC (50-150 mA) and finally to abnormal ISC (200-300 mA) processes. By fitting and decomposing the current-dependent MEL traces of the unbalanced and balanced devices, we find that the ISC and RISC processes in these two devices first enhance but then weaken as the bias-current increases. These non-monotonic current-dependent ISC and RISC processes are attributed to the competition between the increased number and the reduced lifetime of polaron-pair and exciplex states during improving the bias-current. Furthermore, the RISC process in the balanced device is stronger than that in the unbalanced device. This is because the balanced carrier injection can facilitate the formation of triplet exciplex states and weaken the triplet-charge annihilation (TQA) process between triplet exciplex states and excessive charge carriers, which leads to the increased number of triplet exciplex states. That is, more triplet exciplex states can convert into singlet exciplex states through the RISC process, causing a higher external quantum efficiency of the balanced device than that of the unbalanced device. Obviously, this work not only deepens the understandings of current-dependent ISC and RISC processes in EB-OLEDs, but also provides insights of device physics for designing and fabricating high-efficiency EB-OLEDs.
{"title":"Various current-dependent intersystem crossing and reverse intersystem crossing processes induced by different charge balances in exciplex-based OLEDs","authors":"Zhao Xi, Chen Jing, Peng Teng, Liu Jun-Hong, Wang bo, Chen Xiao-Li, Xiong Zu-Hong","doi":"10.7498/aps.72.20230765","DOIUrl":"https://doi.org/10.7498/aps.72.20230765","url":null,"abstract":"Intersystem crossing (ISC) and reverse ISC (RISC) between singlet and triplet polaron-pair and exciplex states are important spin-mixing processes in exciplex-based organic light-emitting diodes (EB-OLEDs). These two processes usually show normal current dependencies which weaken with increasing the bias-current. This is because the increase in the bias-current is realized by improving the device bias-voltage. When the bias-voltage rises, the electric field within the device enhances, which facilitates the electric-field-induced dissociation of polaron-pair and exciplex states and then reduces their lifetime. That is, less polaron-pair and exciplex states participate in the ISC and RISC processes leading to the reduction of these two processes. Here, magneto-electroluminescence (MEL) is used as a fingerprint probing tool to observe various current-dependent ISC and RISC processes in EB-OLEDs with different charge balances via modifying the device hole-injection layer. Interestingly, current-dependent MEL traces of the unbalanced device display a conversion from normal ISC (1-25 mA) to abnormal ISC (25-200 mA) processes, whereas those of the balanced device show conversions from normal ISC (1-5 mA) to abnormal RISC (10-50 mA) and then to normal RISC (50-150 mA) and finally to abnormal ISC (200-300 mA) processes. By fitting and decomposing the current-dependent MEL traces of the unbalanced and balanced devices, we find that the ISC and RISC processes in these two devices first enhance but then weaken as the bias-current increases. These non-monotonic current-dependent ISC and RISC processes are attributed to the competition between the increased number and the reduced lifetime of polaron-pair and exciplex states during improving the bias-current. Furthermore, the RISC process in the balanced device is stronger than that in the unbalanced device. This is because the balanced carrier injection can facilitate the formation of triplet exciplex states and weaken the triplet-charge annihilation (TQA) process between triplet exciplex states and excessive charge carriers, which leads to the increased number of triplet exciplex states. That is, more triplet exciplex states can convert into singlet exciplex states through the RISC process, causing a higher external quantum efficiency of the balanced device than that of the unbalanced device. Obviously, this work not only deepens the understandings of current-dependent ISC and RISC processes in EB-OLEDs, but also provides insights of device physics for designing and fabricating high-efficiency EB-OLEDs.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"57 10 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78043960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shanshan Shen, Guo Hua Gu, Chen Qian, He Rui qing, Cao qing qing
In this paper, we demonstrate a new imaging architecture called time-space united coding spread spectrum single photon counting imaging technique by combining the space coding based single-pixel imaging technology and spread spectrum time coding based scanning imaging technology. This method has the advantages of avoiding range ambiguity and large time bandwidth product. Under the interference of noise this method can accurately restore depth images. In this paper, the time-space united correlation nonlinear detection model based on single photon detection, forward imaging model and Signal-to-Noise Ratio model is derived, and the depth image is restored by convex optimization inversion algorithm. The theoretical model and simulation experiments show that, compared with the traditional single pixel imaging method based on spatial coding, this method improves the quality of scene reconstruction. Using m-sequence as time coding，imaging has higher noise robustness. In addition, compared with the traditional space coding single pixel imaging technology, the imaging mean square error of the proposed method is reduced by 5 times and the imaging mean squared error is reduced by 10 times after introducing the second correlated method. The proposed imaging architecture in this paper may provide a new path for non-scanning lidar imaging methods.
{"title":"The Research On Time-space United Coding Spread Spectrum Single Photon Counting Imaging Method","authors":"Shanshan Shen, Guo Hua Gu, Chen Qian, He Rui qing, Cao qing qing","doi":"10.7498/aps.72.20221438","DOIUrl":"https://doi.org/10.7498/aps.72.20221438","url":null,"abstract":"In this paper, we demonstrate a new imaging architecture called time-space united coding spread spectrum single photon counting imaging technique by combining the space coding based single-pixel imaging technology and spread spectrum time coding based scanning imaging technology. This method has the advantages of avoiding range ambiguity and large time bandwidth product. Under the interference of noise this method can accurately restore depth images. In this paper, the time-space united correlation nonlinear detection model based on single photon detection, forward imaging model and Signal-to-Noise Ratio model is derived, and the depth image is restored by convex optimization inversion algorithm. The theoretical model and simulation experiments show that, compared with the traditional single pixel imaging method based on spatial coding, this method improves the quality of scene reconstruction. Using m-sequence as time coding，imaging has higher noise robustness. In addition, compared with the traditional space coding single pixel imaging technology, the imaging mean square error of the proposed method is reduced by 5 times and the imaging mean squared error is reduced by 10 times after introducing the second correlated method. The proposed imaging architecture in this paper may provide a new path for non-scanning lidar imaging methods.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"48 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80030702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most shallow water geoacoustic inversions based on modal dispersion cannot reliably estimate the deep geoacoustic parameters. Because these studies focus on the dispersions of water waves but ignore the dispersions of ground waves. Therefore, this paper studied a Bayesian geoacoustic inversion based on wideband modal dispersions of water waves and ground waves. Firstly, the modal dispersion curves with Airy phase components were discussed. Secondly, the Bayesian inversion theory and a novel sample-efficient inference algorithm, namely Variational Bayesian Monte Carlo, were introduced briefly. In the Bayesian inversion, the posterior probability densities of unknown parameters are inferred, which can provide the prediction closest to the observation data and the uncertainty of the prediction. Considering that the forward acoustic model is computationally intensive, the posterior analysis is carried out by using the Variational Bayesian Monte Carlo method. It is performed by finding the variational distribution closest to the target distribution and requires less computation time than the Markov chain Monto Carlo method. In the simulation study, a range-independent two-layer seabed, including the sediment layer and basement layer, is modeled, assuming that the water column is homogeneous. The function of shear wave in waveguide was ignored. The compressional sound speed of the sediment layer varied linearly from c1U to c1L between 0 and h1, while other geoacoustic parameters were constant. By comparing the inversion results with and without the information of ground waves for different signal-to-noise ratios, it can be concluded that the deep geoacoustic parameters are more sensitive to the dispersions of ground waves. And then, a shallow-water experimental study was carried out in the Bohai Sea of China. The average water depth was about 20m. The wideband pulse signals were recorded by a hydrophone with a sensitivity of -170dB re 1V/μPa. The received signals included well-defined Airy phase components, and the modal dispersion curves of water waves and ground waves were extracted accurately. The experimental results indicated that the Bayesian inversion combining water and ground wave dispersions can not only estimate the deep geoacoustic parameters reliably, but also reduce the inversion uncertainties of other model parameters, such as the shallow geoacoustic parameters, water depth, and so on. The estimated source-receiver range and water sound speed are close to their measured values. The modal dispersion curves predicted by the posterior mean samples were in good agreement with those extracted from the experimental data at different ranges. In addition, the well forecast of transmission loss also demonstrated the reliability of the joint inversion.
{"title":"A Bayesian geoacoustic inversion based on modal dispersions of water wave and ground wave","authors":"Hao Wang, Duan Rui, Yang Kun-De","doi":"10.7498/aps.72.20221717","DOIUrl":"https://doi.org/10.7498/aps.72.20221717","url":null,"abstract":"Most shallow water geoacoustic inversions based on modal dispersion cannot reliably estimate the deep geoacoustic parameters. Because these studies focus on the dispersions of water waves but ignore the dispersions of ground waves. Therefore, this paper studied a Bayesian geoacoustic inversion based on wideband modal dispersions of water waves and ground waves. Firstly, the modal dispersion curves with Airy phase components were discussed. Secondly, the Bayesian inversion theory and a novel sample-efficient inference algorithm, namely Variational Bayesian Monte Carlo, were introduced briefly. In the Bayesian inversion, the posterior probability densities of unknown parameters are inferred, which can provide the prediction closest to the observation data and the uncertainty of the prediction. Considering that the forward acoustic model is computationally intensive, the posterior analysis is carried out by using the Variational Bayesian Monte Carlo method. It is performed by finding the variational distribution closest to the target distribution and requires less computation time than the Markov chain Monto Carlo method. In the simulation study, a range-independent two-layer seabed, including the sediment layer and basement layer, is modeled, assuming that the water column is homogeneous. The function of shear wave in waveguide was ignored. The compressional sound speed of the sediment layer varied linearly from c1U to c1L between 0 and h1, while other geoacoustic parameters were constant. By comparing the inversion results with and without the information of ground waves for different signal-to-noise ratios, it can be concluded that the deep geoacoustic parameters are more sensitive to the dispersions of ground waves. And then, a shallow-water experimental study was carried out in the Bohai Sea of China. The average water depth was about 20m. The wideband pulse signals were recorded by a hydrophone with a sensitivity of -170dB re 1V/μPa. The received signals included well-defined Airy phase components, and the modal dispersion curves of water waves and ground waves were extracted accurately. The experimental results indicated that the Bayesian inversion combining water and ground wave dispersions can not only estimate the deep geoacoustic parameters reliably, but also reduce the inversion uncertainties of other model parameters, such as the shallow geoacoustic parameters, water depth, and so on. The estimated source-receiver range and water sound speed are close to their measured values. The modal dispersion curves predicted by the posterior mean samples were in good agreement with those extracted from the experimental data at different ranges. In addition, the well forecast of transmission loss also demonstrated the reliability of the joint inversion.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"47 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80377081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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