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":"Acta Physica Sinica","volume":null,"pages":null},"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}
Liu Yi-Jun, Chen Yi-Wei, Zhu Yu-Jian, Huang Yan, An Dong-Dong, Li Qing-Xin, Gan Qi-Kang, Zhu Wang, Song Jun-Wei, Wang Kai-Yuan, Wei Ling-Nan, Zong Qi-Jun, Liu Shuo-Han, Li Shi-Wei, Liu Zhi, Zhang Qi, Xu Ying-Hai, Cao Xin-Yu, Yang Ao, Wang Hao-Lin, Yang Bing, Andy Shen, Yu Ge-Liang, Wang Lei
Flat band with nearly zero dispersion can be engineered by twisting van der Waals materials relative to each other, and lead to a series of strongly correlated states, for example unconventional superconductivity, correlated insulating state, orbital magnetism. The bandwidth and topological property of electronic band structure in twisted double bilayer graphene is tunable by an external displacement field. This system could be an excellent quantum simulator to study the interplay between topological phase transition and strong electron correlation. Theoretical calculation shows that the broken of C2x symmetry in TDBG by an electric displacement field leads to finite Chern numbers at the lowest conduction and valence band near charge neutrality. Hence Chern insulator may emergent from this topological non-trivial flat band under strong electron interaction. Here, we observe Chern insulator state with Chern number 4 at filling factor v=1 under small magnetic fields on twisted double bilayer graphene with twist angle 1.48°. Moreover, the longitudinal resistance shows a peak under a parallel magnetic field and increases temperature and field, that is analogous to the Pomeranchuk effect in 3He. This phenomenon indicates that Chern insulator at v=1 may originate from isospin polarization.
{"title":"Isospin polarized Chern insulator state of C=4 in twisted double bilayer graphene","authors":"Liu Yi-Jun, Chen Yi-Wei, Zhu Yu-Jian, Huang Yan, An Dong-Dong, Li Qing-Xin, Gan Qi-Kang, Zhu Wang, Song Jun-Wei, Wang Kai-Yuan, Wei Ling-Nan, Zong Qi-Jun, Liu Shuo-Han, Li Shi-Wei, Liu Zhi, Zhang Qi, Xu Ying-Hai, Cao Xin-Yu, Yang Ao, Wang Hao-Lin, Yang Bing, Andy Shen, Yu Ge-Liang, Wang Lei","doi":"10.7498/aps.72.20230497","DOIUrl":"https://doi.org/10.7498/aps.72.20230497","url":null,"abstract":"Flat band with nearly zero dispersion can be engineered by twisting van der Waals materials relative to each other, and lead to a series of strongly correlated states, for example unconventional superconductivity, correlated insulating state, orbital magnetism. The bandwidth and topological property of electronic band structure in twisted double bilayer graphene is tunable by an external displacement field. This system could be an excellent quantum simulator to study the interplay between topological phase transition and strong electron correlation. Theoretical calculation shows that the broken of C2x symmetry in TDBG by an electric displacement field leads to finite Chern numbers at the lowest conduction and valence band near charge neutrality. Hence Chern insulator may emergent from this topological non-trivial flat band under strong electron interaction. Here, we observe Chern insulator state with Chern number 4 at filling factor v=1 under small magnetic fields on twisted double bilayer graphene with twist angle 1.48°. Moreover, the longitudinal resistance shows a peak under a parallel magnetic field and increases temperature and field, that is analogous to the Pomeranchuk effect in 3He. This phenomenon indicates that Chern insulator at v=1 may originate from isospin polarization.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79879134","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":"Acta Physica Sinica","volume":null,"pages":null},"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}
Since the Whitham modulation theory was first proposed in 1965, it has been widely concerned because of its superiority in studying dispersive fluid dynamics and dealing with discontinuous initial value problems. In this paper, the Whitham modulation theory of the defocusing nonlinear Schrödinger equation is developed, the classification and evolution of the solutions of discontinuous initial value problem are studied. Moreover, the region of dispersive shock wave, the region rarefaction wave, the region of unmodulated wave and the plateau region are distinguished. Particularly, the correctness of the results is verified by direct numerical simulation. Specifically, the solutions of 0-phase and 1-phase and their corresponding Whitham equations are derived by the finite gap integration method. Also the Whitham equation of genus N corresponding to the N-phase periodic wave solution is derived. The basic structures of rarefaction wave and dispersive shock wave are given, in which the boundaries of the regions are calculated in detail. The Riemann invariants and density distributions of dispersive fluids in each case are discussed. When the initial value is fixed as a special one, the vacuum point is considered and analyzed in detail. In addition, the oscillating front and the soliton front in the dispersive shock wave are considered. In fact, the Whitham modulation theory has many wonderful applications in real physics and engineering. The dam problem is investigated as a special Riemann problem, the piston problem of dispersive fluid is analyzed, and the novel undular bores are found.
{"title":"The Whitham Modulation Theory of Defocusing Nonlinear Schrödinger Equation and the Classification and Evolutions of Solutions With Initial Discontinuity","authors":"Gong Rui-Zhi, Wang Deng-Shan","doi":"10.7498/aps.72.20230172","DOIUrl":"https://doi.org/10.7498/aps.72.20230172","url":null,"abstract":"Since the Whitham modulation theory was first proposed in 1965, it has been widely concerned because of its superiority in studying dispersive fluid dynamics and dealing with discontinuous initial value problems. In this paper, the Whitham modulation theory of the defocusing nonlinear Schrödinger equation is developed, the classification and evolution of the solutions of discontinuous initial value problem are studied. Moreover, the region of dispersive shock wave, the region rarefaction wave, the region of unmodulated wave and the plateau region are distinguished. Particularly, the correctness of the results is verified by direct numerical simulation. Specifically, the solutions of 0-phase and 1-phase and their corresponding Whitham equations are derived by the finite gap integration method. Also the Whitham equation of genus N corresponding to the N-phase periodic wave solution is derived. The basic structures of rarefaction wave and dispersive shock wave are given, in which the boundaries of the regions are calculated in detail. The Riemann invariants and density distributions of dispersive fluids in each case are discussed. When the initial value is fixed as a special one, the vacuum point is considered and analyzed in detail. In addition, the oscillating front and the soliton front in the dispersive shock wave are considered. In fact, the Whitham modulation theory has many wonderful applications in real physics and engineering. The dam problem is investigated as a special Riemann problem, the piston problem of dispersive fluid is analyzed, and the novel undular bores are found.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79036568","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}
Li De-Zhang, Lu Zhi-Wei, Zhao Yu-Jun, Yang Xiao-Bao
The stochastic dynamics of spin semiclassical system at finite temperature is usually described by stochastic Landau-Lifshitz equation. In this work, the stochastic differential equation for spin semiclassical system is studied. The generalized formulation of effective Langevin equation and the corresponding Fokker-Planck equation are derived. The obtained effective Langevin equation offers an accurate description of the distribution in the canonical ensemble for spin semiclassical system. When the damping term and the stochastic term vanish, the effective Langevin equation reduces to the semiclassical equation of motion for spin system. Hence, the effective Langevin equation can be seen as a generalization of the stochastic Landau-Lifshitz equation. The explicit expressions for the effective Langevin equation and the corresponding Fokker-Planck equation are shown in both Cartesian and Spherical coordinates. It is demonstrated that, the longitudinal effect can be easily illustrated from the expressions in Spherical coordinates. The effective Langevin equation is applied to the simple system of a single spin in a constant magnetic field. In choosing an appropriate form, the Langevin equation can be easily solved and the stationary Boltzmann distribution can be obtained. The correctness of the Langevin approach to the spin semiclassical system is thus confirmed.
{"title":"Study of the generalization of spin semiclassical Langevin equation","authors":"Li De-Zhang, Lu Zhi-Wei, Zhao Yu-Jun, Yang Xiao-Bao","doi":"10.7498/aps.72.20230106","DOIUrl":"https://doi.org/10.7498/aps.72.20230106","url":null,"abstract":"The stochastic dynamics of spin semiclassical system at finite temperature is usually described by stochastic Landau-Lifshitz equation. In this work, the stochastic differential equation for spin semiclassical system is studied. The generalized formulation of effective Langevin equation and the corresponding Fokker-Planck equation are derived. The obtained effective Langevin equation offers an accurate description of the distribution in the canonical ensemble for spin semiclassical system. When the damping term and the stochastic term vanish, the effective Langevin equation reduces to the semiclassical equation of motion for spin system. Hence, the effective Langevin equation can be seen as a generalization of the stochastic Landau-Lifshitz equation. The explicit expressions for the effective Langevin equation and the corresponding Fokker-Planck equation are shown in both Cartesian and Spherical coordinates. It is demonstrated that, the longitudinal effect can be easily illustrated from the expressions in Spherical coordinates. The effective Langevin equation is applied to the simple system of a single spin in a constant magnetic field. In choosing an appropriate form, the Langevin equation can be easily solved and the stationary Boltzmann distribution can be obtained. The correctness of the Langevin approach to the spin semiclassical system is thus confirmed.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81501989","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}
Shuai Han, Qiubo Guo, Yaxiang Lu, Liquan Chen, Yong-Sheng Hu
Aqueous alkali-metal-ion batteries are a popular frontier research area, expected to apply for large-scale energy storage due to their high safety, low cost, and environmental friendliness. Depending on diversified social development, batteries ought to function in various ambient, including polar regions and high-altitude locales. Delivering excellent electrochemical performance at low temperatures is crucial to develop aqueous alkali-metal-ion batteries. This review summarizes the representative research progress in the field of aqueous low-temperature alkali-metal-ion batteries in recent years,based on the subjects of electrolyte, electrode, and interface. Firstly, we discussed the challenges of aqueous alkali-metal-ion batteries operated at low temperatures and the corresponding failure mechanisms. At subzero temperatures, aqueous alkali-metal-ion batteries couldn't work or exhibit little capacity, arising from the frozen electrolytes, electrode materials with slow kinetics, and huge interface impedances, which seriously limits their wide application in low-temperature conditions. Then, combined with the latest research work, various strategies have been investigated to improve the electrochemical performance of batteries at low temperatures. To date, the strategies for reducing the freezing point of electrolytes have primarily focused on breaking H-bonds between free water molecules by increasing salt concentration, adding organic/inorganic additives, and using hydrogel as electrolytes. In terms of electrodes, the related studies have concentrated on regulating the structure and morphology of electrodes, introducing the dual ion battery mechanism, and using organic materials and Zn electrodes to alleviate the slow ion dynamics of electrodes. In addition, adding appropriate organic solvents that can generate protective layers with low interface impedance on the electrode surface in the electrolyte can also improve the low-temperature performance of aqueous alkali-metal-ion batteries. Finally, we evaluated multi-dimensionally all strategies, expected to provide a comprehensive reference and point out the direction for the further improvement and practical application of the aqueous alkali-metal-ion batteries at low temperatures.
{"title":"Recent Progress in Aqueous Alkali-metal-ion batteries at low temperatures","authors":"Shuai Han, Qiubo Guo, Yaxiang Lu, Liquan Chen, Yong-Sheng Hu","doi":"10.7498/aps.72.20230024","DOIUrl":"https://doi.org/10.7498/aps.72.20230024","url":null,"abstract":"Aqueous alkali-metal-ion batteries are a popular frontier research area, expected to apply for large-scale energy storage due to their high safety, low cost, and environmental friendliness. Depending on diversified social development, batteries ought to function in various ambient, including polar regions and high-altitude locales. Delivering excellent electrochemical performance at low temperatures is crucial to develop aqueous alkali-metal-ion batteries. This review summarizes the representative research progress in the field of aqueous low-temperature alkali-metal-ion batteries in recent years,based on the subjects of electrolyte, electrode, and interface. Firstly, we discussed the challenges of aqueous alkali-metal-ion batteries operated at low temperatures and the corresponding failure mechanisms. At subzero temperatures, aqueous alkali-metal-ion batteries couldn't work or exhibit little capacity, arising from the frozen electrolytes, electrode materials with slow kinetics, and huge interface impedances, which seriously limits their wide application in low-temperature conditions. Then, combined with the latest research work, various strategies have been investigated to improve the electrochemical performance of batteries at low temperatures. To date, the strategies for reducing the freezing point of electrolytes have primarily focused on breaking H-bonds between free water molecules by increasing salt concentration, adding organic/inorganic additives, and using hydrogel as electrolytes. In terms of electrodes, the related studies have concentrated on regulating the structure and morphology of electrodes, introducing the dual ion battery mechanism, and using organic materials and Zn electrodes to alleviate the slow ion dynamics of electrodes. In addition, adding appropriate organic solvents that can generate protective layers with low interface impedance on the electrode surface in the electrolyte can also improve the low-temperature performance of aqueous alkali-metal-ion batteries. Finally, we evaluated multi-dimensionally all strategies, expected to provide a comprehensive reference and point out the direction for the further improvement and practical application of the aqueous alkali-metal-ion batteries at low temperatures.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81723624","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}
Shi Lu-lin, Cheng Rui, Wang Zhao, Cao Shi-Quan, Yang Jie, Zhou Ze-Xian, Chen Yan-Hong, Wang Guo-Dong, Hui De-Xuan, Jin Xue-Jian, Wu Xiao-Xia, Lei Yu, Wang Yu-Yu, Su Mao-Gen
Ion energy loss in the interaction between highly charged ions and dense plasmas near the Bohr velocity energy region is one of the important physical problems in the field of high-energy density physics driven by intense heavy ion beams. Based on the 320 kV experimental platform at the Institute of Modern Physics, Chinese Academy of Sciences, an experimental setup is newly built for the research of interaction between ions and laser-produced plasmas near the Bohr velocity, where the ion energy loss and charge state distribution can be experimentally investigated. This paper introduces the new setup in detail, including: the generation and controlling of pulsed ions beam ( ≥ 200 ns); the preparation of high-density laser plasma target (1017 ~ 1021 cm-3); the diagnostics of plasmas and the developed high energy resolution ion measurement system (＜1%). In the experiment, the charge distribution was measured where the Xe15+ ions with 4 MeV penetrated through the laser-produced Al plasma target. The charge-state analysis device observed that the different resutls without and with the plasmas, in which the outgoing Xe ions charge-state changes correspondingly from the 15+ to 10+, thus the electron capture process is believed dominates. In addition, the proton energy loss was measred too by using the magnetic spectrometer, and the experimental energy loss is about 2.0 keV which is significantly higher than those theoretical predictions by a factor of 30%. In our consideration, the possible reason can be deduced to that in the near Bohr velocity energy regime, the first-order Born approximation condition is not valid, thus the Bethe and SSM models fail to represent the experimental results. In future, a systematic study will be performed based on our ions-plasmas ineteraction setups and the energy loss and charge state data will be introduced.
{"title":"Experimental setup for interaction between highly charged ions and Laser-produced plasma near the Bohr velocity energy region","authors":"Shi Lu-lin, Cheng Rui, Wang Zhao, Cao Shi-Quan, Yang Jie, Zhou Ze-Xian, Chen Yan-Hong, Wang Guo-Dong, Hui De-Xuan, Jin Xue-Jian, Wu Xiao-Xia, Lei Yu, Wang Yu-Yu, Su Mao-Gen","doi":"10.7498/aps.72.20230214","DOIUrl":"https://doi.org/10.7498/aps.72.20230214","url":null,"abstract":"Ion energy loss in the interaction between highly charged ions and dense plasmas near the Bohr velocity energy region is one of the important physical problems in the field of high-energy density physics driven by intense heavy ion beams. Based on the 320 kV experimental platform at the Institute of Modern Physics, Chinese Academy of Sciences, an experimental setup is newly built for the research of interaction between ions and laser-produced plasmas near the Bohr velocity, where the ion energy loss and charge state distribution can be experimentally investigated. This paper introduces the new setup in detail, including: the generation and controlling of pulsed ions beam ( ≥ 200 ns); the preparation of high-density laser plasma target (1017 ~ 1021 cm-3); the diagnostics of plasmas and the developed high energy resolution ion measurement system (＜1%). In the experiment, the charge distribution was measured where the Xe15+ ions with 4 MeV penetrated through the laser-produced Al plasma target. The charge-state analysis device observed that the different resutls without and with the plasmas, in which the outgoing Xe ions charge-state changes correspondingly from the 15+ to 10+, thus the electron capture process is believed dominates. In addition, the proton energy loss was measred too by using the magnetic spectrometer, and the experimental energy loss is about 2.0 keV which is significantly higher than those theoretical predictions by a factor of 30%. In our consideration, the possible reason can be deduced to that in the near Bohr velocity energy regime, the first-order Born approximation condition is not valid, thus the Bethe and SSM models fail to represent the experimental results. In future, a systematic study will be performed based on our ions-plasmas ineteraction setups and the energy loss and charge state data will be introduced.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84213310","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 research on the macroscopic properties of neutron stars has great significance for revealing the internal composition and structure of neutron stars. We have analyzed the influence of δ mesons on the equation of states, the maximum masses, the tidal Love numbers and the tidal deformabilities for the conventional neutron stars and the hyperon stars within the relativistic mean field theory. It is found that the presence of δ mesons can strengthen the tidal deformabilities of the low and medium-mass conventional neutron stars (or hyperon stars). However, the strengthening trends of the tidal deformabilities with δ mesons are gradually weakened as the increase of the masses for the conventional neutron (or hyperon stars). Especially for massive hyperon stars, the tidal deformabilities with δ mesons is weaker than the corresponding values without δ mesons. Moreover, the presence of hyperons can reduce the tidal deformabilities of stars with the same mass. For the stars containing δ mesons, only the tidal deformabilities in the hyperon stars with Λ, Σ and Ξ hyperons can satisfy both constraints of GW170817 and GW190814 events under the parameters selected in the paper. As the date on gravitational waves associated with the neutron stars gradually increase, which will provide a possible way for judging the hyperon species in the hyperon stars.
{"title":"Study on the tidal deformabilities of neutron stars in the relativistic mean field approach with δ mesons","authors":"Diao Bin, Xu Yan, Huang Xiu-Lin, Wang Yi-Bo","doi":"10.7498/aps.72.20221599","DOIUrl":"https://doi.org/10.7498/aps.72.20221599","url":null,"abstract":"The research on the macroscopic properties of neutron stars has great significance for revealing the internal composition and structure of neutron stars. We have analyzed the influence of δ mesons on the equation of states, the maximum masses, the tidal Love numbers and the tidal deformabilities for the conventional neutron stars and the hyperon stars within the relativistic mean field theory. It is found that the presence of δ mesons can strengthen the tidal deformabilities of the low and medium-mass conventional neutron stars (or hyperon stars). However, the strengthening trends of the tidal deformabilities with δ mesons are gradually weakened as the increase of the masses for the conventional neutron (or hyperon stars). Especially for massive hyperon stars, the tidal deformabilities with δ mesons is weaker than the corresponding values without δ mesons. Moreover, the presence of hyperons can reduce the tidal deformabilities of stars with the same mass. For the stars containing δ mesons, only the tidal deformabilities in the hyperon stars with Λ, Σ and Ξ hyperons can satisfy both constraints of GW170817 and GW190814 events under the parameters selected in the paper. As the date on gravitational waves associated with the neutron stars gradually increase, which will provide a possible way for judging the hyperon species in the hyperon stars.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84326489","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}
Reservoir computing (RC) is a simplified recurrent neural network, can be implemented by using a nonlinear system with delay feedback, called as delay-based RC. Various nonlinear nodes and feedback loop structures are proposed. Most works are based on the dynamical responses in intensity of the nonlinear systems. There are also a photoelectric RC system based on wavelength dynamics and an all-optical RC based on the phase dynamics of a semiconductor laser with optical feedback, as well as so-called polarization dynamics of a vertical cavity surface emitting laser (VCSEL). However, these VCSEL-RCs actually are based on the intensity dynamics of two mutually orthogonal polarization modes, or polarization-resolved intensity dynamics. The RC based on rich dynamical responses in polarization has not yet been seen. A semiconductor optical amplifier (SOA) fiber ring laser can produce rich dynamical states in polarization, is used in optical chaotic secure communication and distributed optical fiber sensing. To further expand the application of polarization dynamics of the SOA fiber ring laser and open up a new direction for the research of optical RC neural network, an all-optical RC system based on polarization dynamics of the ring laser is proposed. The ring laser is used as the reservoir, and the SOA as the nonlinear node. After the input signal is masked according to a synchronization scheme, it is injected into the reservoir by intensity modulation for a continuous wave generated by a super-luminescent light emitting diode (SLED). The dynamical response in polarization of the ring laser is detected by a polarizer and a photodetector. The influences of the SOA operation current, output power of the SLED and attenuation of a variable optical attenuator (VOA) in the fiber loop on the polarization dynamic characteristic, mainly refers to the output degree of polarization, of the laser are analyzed experimentally. The fading memory abilities and nonlinear responses of the RC system based on the polarization dynamic response and intensity dynamic response are compared in experiment. The influences of output power of the SLED and attenuation of the VOA on fading memory ability, consistency and separation of the RC system based on the two kinds of dynamic responses are investigated experimentally. Thus the range of the VOA attenuation is determined. The network performance of the polarization dynamics RC system is evaluated by processing the Santa Fe time series prediction task and the multi-waveform recognition task. The prediction error can be as low as 0.0058 for the time series prediction task, and the accuracy can be as high as 100% for the recognition task under the appropriate system parameters and only 30 virtual nodes. The experimental results show that the polarization dynamics RC system has good prediction performance and classification ability, which are comparable to the existing intensity dynamics RC system based on the ring laser. The system
{"title":"All-optical reservoir computing system based on polarization dynamics","authors":"Fang Nian, Qian Ruolan, Wang Shuai","doi":"10.7498/aps.72.20230722","DOIUrl":"https://doi.org/10.7498/aps.72.20230722","url":null,"abstract":"Reservoir computing (RC) is a simplified recurrent neural network, can be implemented by using a nonlinear system with delay feedback, called as delay-based RC. Various nonlinear nodes and feedback loop structures are proposed. Most works are based on the dynamical responses in intensity of the nonlinear systems. There are also a photoelectric RC system based on wavelength dynamics and an all-optical RC based on the phase dynamics of a semiconductor laser with optical feedback, as well as so-called polarization dynamics of a vertical cavity surface emitting laser (VCSEL). However, these VCSEL-RCs actually are based on the intensity dynamics of two mutually orthogonal polarization modes, or polarization-resolved intensity dynamics. The RC based on rich dynamical responses in polarization has not yet been seen. A semiconductor optical amplifier (SOA) fiber ring laser can produce rich dynamical states in polarization, is used in optical chaotic secure communication and distributed optical fiber sensing. To further expand the application of polarization dynamics of the SOA fiber ring laser and open up a new direction for the research of optical RC neural network, an all-optical RC system based on polarization dynamics of the ring laser is proposed. The ring laser is used as the reservoir, and the SOA as the nonlinear node. After the input signal is masked according to a synchronization scheme, it is injected into the reservoir by intensity modulation for a continuous wave generated by a super-luminescent light emitting diode (SLED). The dynamical response in polarization of the ring laser is detected by a polarizer and a photodetector. The influences of the SOA operation current, output power of the SLED and attenuation of a variable optical attenuator (VOA) in the fiber loop on the polarization dynamic characteristic, mainly refers to the output degree of polarization, of the laser are analyzed experimentally. The fading memory abilities and nonlinear responses of the RC system based on the polarization dynamic response and intensity dynamic response are compared in experiment. The influences of output power of the SLED and attenuation of the VOA on fading memory ability, consistency and separation of the RC system based on the two kinds of dynamic responses are investigated experimentally. Thus the range of the VOA attenuation is determined. The network performance of the polarization dynamics RC system is evaluated by processing the Santa Fe time series prediction task and the multi-waveform recognition task. The prediction error can be as low as 0.0058 for the time series prediction task, and the accuracy can be as high as 100% for the recognition task under the appropriate system parameters and only 30 virtual nodes. The experimental results show that the polarization dynamics RC system has good prediction performance and classification ability, which are comparable to the existing intensity dynamics RC system based on the ring laser. The system","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85187686","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}
Dirac quantum materials comprise a broad category of condensed matter systems characterized by low-energy excitations described by the Dirac equation. These excitations, which can manifest as either collective states or band structure effects, have been identified in a wide range of systems, from exotic quantum fluids to crystalline materials. Over the past several decades, they have sparked extensive experimental and theoretical investigations in various materials, such as topological insulators and topological semimetals. The study of Dirac quantum materials has also opened up new possibilities for topological quantum computing, giving rise to a burgeoning field of physics and offering a novel platform for realizing rich topological phases, including various quantum Hall effects and topological superconducting phases. Furthermore, the topologically non-trivial band structures of Dirac quantum materials give rise to plentiful intriguing transport phenomena, including longitudinal negative magnetoresistance, quantum interference effects, and helical magnetic effects, among others. Currently, numerous transport phenomena in Dirac quantum materials remain poorly understood from a theoretical standpoint, such as linear magnetoresistance in weak fields, anomalous Hall effects in nonmagnetic materials, and three-dimensional quantum Hall effects. Investigating these transport properties will not only deepen our understanding of Dirac quantum materials but also provide crucial insights for their potential applications in spintronics and quantum computing. This review provides a comprehensive overview of the quantum transport theory and quantum anomaly effects related to the Dirac equation, with a focus on massive Dirac fermions and quantum anomalous semimetals. Additionally, it offers insights into the realization of parity anomaly and half-quantized quantum Hall effects in semi-magnetic topological insulators. Lastly, the review discusses the key scientific questions of interest in the field of quantum transport theory.
{"title":"Recent progress of transport theory in Dirac quantum materials","authors":"Wang Huan-Wen, Fu Bo, Shen Shun-Qing","doi":"10.7498/aps.72.20230672","DOIUrl":"https://doi.org/10.7498/aps.72.20230672","url":null,"abstract":"Dirac quantum materials comprise a broad category of condensed matter systems characterized by low-energy excitations described by the Dirac equation. These excitations, which can manifest as either collective states or band structure effects, have been identified in a wide range of systems, from exotic quantum fluids to crystalline materials. Over the past several decades, they have sparked extensive experimental and theoretical investigations in various materials, such as topological insulators and topological semimetals. The study of Dirac quantum materials has also opened up new possibilities for topological quantum computing, giving rise to a burgeoning field of physics and offering a novel platform for realizing rich topological phases, including various quantum Hall effects and topological superconducting phases. Furthermore, the topologically non-trivial band structures of Dirac quantum materials give rise to plentiful intriguing transport phenomena, including longitudinal negative magnetoresistance, quantum interference effects, and helical magnetic effects, among others. Currently, numerous transport phenomena in Dirac quantum materials remain poorly understood from a theoretical standpoint, such as linear magnetoresistance in weak fields, anomalous Hall effects in nonmagnetic materials, and three-dimensional quantum Hall effects. Investigating these transport properties will not only deepen our understanding of Dirac quantum materials but also provide crucial insights for their potential applications in spintronics and quantum computing. This review provides a comprehensive overview of the quantum transport theory and quantum anomaly effects related to the Dirac equation, with a focus on massive Dirac fermions and quantum anomalous semimetals. Additionally, it offers insights into the realization of parity anomaly and half-quantized quantum Hall effects in semi-magnetic topological insulators. Lastly, the review discusses the key scientific questions of interest in the field of quantum transport theory.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85208264","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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