None Lv Qing-Xian, None Li Sai, None Tu Hai-Tao, None Liao Kai-Yu, None Liang Zhen-Tao, None Yan Hui, None Zhu Shi-Liang
The superconductor and cold atoms hybrid quantum system is poised to realize fast quantum gates, long-life quantum storage and long-distance transmission through optical fibers, making it one of the most promising hybrid quantum systems for achieving optical interconnection between two superconducting quantum computers. This paper provides a comprehensive review of recent research advancements in the optical interconnection of two superconducting quantum computers, based on the superconductor and cold atoms hybrid quantum system. This encompasses the coherent coupling between superconducting chips and cold atoms, the coherent microwave-to-optics conversion, and the long-range microwave interconnection between superconducting qubits and quantum converters. The system is expected to provide a physical and technical foundation for practical optical-fiber interconnection of two superconducting quantum computers, and have broad applications in distributed superconducting quantum computation and hybrid quantum networks.
{"title":"Superconductor and cold atoms hybrid quantum system","authors":"None Lv Qing-Xian, None Li Sai, None Tu Hai-Tao, None Liao Kai-Yu, None Liang Zhen-Tao, None Yan Hui, None Zhu Shi-Liang","doi":"10.7498/aps.72.20230985","DOIUrl":"https://doi.org/10.7498/aps.72.20230985","url":null,"abstract":"The superconductor and cold atoms hybrid quantum system is poised to realize fast quantum gates, long-life quantum storage and long-distance transmission through optical fibers, making it one of the most promising hybrid quantum systems for achieving optical interconnection between two superconducting quantum computers. This paper provides a comprehensive review of recent research advancements in the optical interconnection of two superconducting quantum computers, based on the superconductor and cold atoms hybrid quantum system. This encompasses the coherent coupling between superconducting chips and cold atoms, the coherent microwave-to-optics conversion, and the long-range microwave interconnection between superconducting qubits and quantum converters. The system is expected to provide a physical and technical foundation for practical optical-fiber interconnection of two superconducting quantum computers, and have broad applications in distributed superconducting quantum computation and hybrid quantum networks.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135060104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on the Bogoliubov-de Gennes equations, we investigate the transport of the Josephson current in a one-dimensional S/FL-F-FR/S junction, where S and F are superconductor and ferromagnet, and FL,R are the left and right interfaces with noncollinear magnetizations. It is found that the FL and FRinterfaces can induce spin-mixing and spin-flip effects, which can transform a part of spin-singlet pairs in the S into equal-spin triplet pairs in the F. For the short S/FL-F-FR/S junction, the spin-singlet pairs and the equal-spin triplet pairs can survive in the F layer. Therefore, with the increase of the ferromagnetic exchange field and the angle difference of interface magnetization rotation, the critical current oscillates on a base level. If the F is transformed into half-metal, only the equal-spin triple pairs exist in the F layer, and the oscillation characteristic of critical current disappears. In addition, the FL and FR interfaces can work as conventional potential barriers. As a result, the critical current exhibits double oscillation behaviors with the increase of ferromagnetic thickness, in which the long-wave oscillation arises from the phase change of the spin-singlet pairs in the ferromagnetic layer, and the short-wave oscillation is caused by the resonant tunneling effect when the spin-singlet pairs and the equal-spin triplet pairs pass through two interfacial barriers.
{"title":"Josephson current induced by spin-mixing Cooper pairs","authors":"None Meng Hao, None Wu Xiu-Qiang","doi":"10.7498/aps.72.20231008","DOIUrl":"https://doi.org/10.7498/aps.72.20231008","url":null,"abstract":"Based on the Bogoliubov-de Gennes equations, we investigate the transport of the Josephson current in a one-dimensional S/F<sub>L</sub>-F-F<sub>R</sub>/S junction, where S and F are superconductor and ferromagnet, and F<sub>L,R</sub> are the left and right interfaces with noncollinear magnetizations. It is found that the F<sub>L</sub> and F<sub>R</sub>interfaces can induce spin-mixing and spin-flip effects, which can transform a part of spin-singlet pairs in the S into equal-spin triplet pairs in the F. For the short S/F<sub>L</sub>-F-F<sub>R</sub>/S junction, the spin-singlet pairs and the equal-spin triplet pairs can survive in the F layer. Therefore, with the increase of the ferromagnetic exchange field and the angle difference of interface magnetization rotation, the critical current oscillates on a base level. If the F is transformed into half-metal, only the equal-spin triple pairs exist in the F layer, and the oscillation characteristic of critical current disappears. In addition, the F<sub>L</sub> and F<sub>R</sub> interfaces can work as conventional potential barriers. As a result, the critical current exhibits double oscillation behaviors with the increase of ferromagnetic thickness, in which the long-wave oscillation arises from the phase change of the spin-singlet pairs in the ferromagnetic layer, and the short-wave oscillation is caused by the resonant tunneling effect when the spin-singlet pairs and the equal-spin triplet pairs pass through two interfacial barriers.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135400407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
None Dong Shan-Shan, None Qin Li-Guo, None Liu Fu-Yao, None Gong Li-Hua, None Huang Jie-Hui
In the issue of quantum evolution, quantum evolution speed is usually quantified by the time rate of change of state distance between the initial sate and its time evolution. In this paper, the path distance of quantum evolution is introduced to study the evolution of a quantum system, through the approach combined with basic theory of quantum evolution and the linear algebra. In a quantum unitary system, the quantum evolution operator contains the path information of the quantum evolution, where the path distance is determined by the principal argument of the eigenvalues of the unitary operator. Accordingly, the instantaneous quantum evolution speed is proportional to the distance between the maximum and minimum eigenvalues of the Hamiltonian. As one of the applications, the path distance and the instantaneous quantum evolution speed could be used to form a new lower bound of the real evolution time, which depends on the evolution operator and Hamiltonian, and is independent of the initial state. It is found that the lower bound presented here is exactly equal to the real evolution time in the range $[0,frac{pi}{2omega_H}]$. The tool of path distance and instantaneous quantum evolution speed introduced here provides new method for the related researches
{"title":"Quantum Evolution Speed Induced by Hamiltonian","authors":"None Dong Shan-Shan, None Qin Li-Guo, None Liu Fu-Yao, None Gong Li-Hua, None Huang Jie-Hui","doi":"10.7498/aps.72.20231009","DOIUrl":"https://doi.org/10.7498/aps.72.20231009","url":null,"abstract":"In the issue of quantum evolution, quantum evolution speed is usually quantified by the time rate of change of state distance between the initial sate and its time evolution. In this paper, the path distance of quantum evolution is introduced to study the evolution of a quantum system, through the approach combined with basic theory of quantum evolution and the linear algebra. In a quantum unitary system, the quantum evolution operator contains the path information of the quantum evolution, where the path distance is determined by the principal argument of the eigenvalues of the unitary operator. Accordingly, the instantaneous quantum evolution speed is proportional to the distance between the maximum and minimum eigenvalues of the Hamiltonian. As one of the applications, the path distance and the instantaneous quantum evolution speed could be used to form a new lower bound of the real evolution time, which depends on the evolution operator and Hamiltonian, and is independent of the initial state. It is found that the lower bound presented here is exactly equal to the real evolution time in the range $[0,frac{pi}{2omega_H}]$. The tool of path distance and instantaneous quantum evolution speed introduced here provides new method for the related researches","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"267 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135400415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Coupled Stuart-Landau limit-cycle system serves as an important paradigmatic model for studying synchronization transitions and collective dynamics in self-sustained nonlinear systems with amplitude degree of freedom. In this paper, we extensively investigate three typical solvable collective behaviors in globally coupled Stuart-Landau limit-cycle systems under mean-field feedback: incoherence, amplitude death, and locked states. In the thermodynamic limit of begin{document}$Nrightarrowinfty$end{document}, the critical condition characterizing the transition from incoherence to synchronization is explicitly obtained via performing the linear stability of the incoherent states, it is found that the synchronization transition occurs at a smaller coupling strength when the strength of mean-field feedback is gradually enhanced; the stable regions of amplitude death are theoretically obtained via an analysis of the linear stability of coupled systems around the origin, it is unveiled that the presence of mean-field feedback is able to effectively eliminate the phenomenon of amplitude death in the coupled systems; furthermore, the existence of locked states is theoretically analyzed, and in particular the boundary of stable amplitude death region is re-derived from the self-consistent relation of the order parameter for the locked states. The study of this work reveals the key role of mean-field feedback in controlling the collective dynamics of coupled nonlinear systems, deepens the understanding of the impact of mean-field feedback technique on the coupling-induced collective behaviors, and is beneficial for us to further understand the emergence rules and the underlying mechanisms of self-organized behaviors in complex coupled systems.
Coupled Stuart-Landau limit-cycle system serves as an important paradigmatic model for studying synchronization transitions and collective dynamics in self-sustained nonlinear systems with amplitude degree of freedom. In this paper, we extensively investigate three typical solvable collective behaviors in globally coupled Stuart-Landau limit-cycle systems under mean-field feedback: incoherence, amplitude death, and locked states. In the thermodynamic limit of <inline-formula><tex-math id="M2">begin{document}$Nrightarrowinfty$end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="20-20230842_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="20-20230842_M2.png"/></alternatives></inline-formula>, the critical condition characterizing the transition from incoherence to synchronization is explicitly obtained via performing the linear stability of the incoherent states, it is found that the synchronization transition occurs at a smaller coupling strength when the strength of mean-field feedback is gradually enhanced; the stable regions of amplitude death are theoretically obtained via an analysis of the linear stability of coupled systems around the origin, it is unveiled that the presence of mean-field feedback is able to effectively eliminate the phenomenon of amplitude death in the coupled systems; furthermore, the existence of locked states is theoretically analyzed, and in particular the boundary of stable amplitude death region is re-derived from the self-consistent relation of the order parameter for the locked states. The study of this work reveals the key role of mean-field feedback in controlling the collective dynamics of coupled nonlinear systems, deepens the understanding of the impact of mean-field feedback technique on the coupling-induced collective behaviors, and is beneficial for us to further understand the emergence rules and the underlying mechanisms of self-organized behaviors in complex coupled systems.
{"title":"Solvable collective dynamics of globally coupled Stuart-Landau limit-cycle systems under mean-field feedback","authors":"None He Su-Juan, None Zou Wei","doi":"10.7498/aps.72.20230842","DOIUrl":"https://doi.org/10.7498/aps.72.20230842","url":null,"abstract":"Coupled Stuart-Landau limit-cycle system serves as an important paradigmatic model for studying synchronization transitions and collective dynamics in self-sustained nonlinear systems with amplitude degree of freedom. In this paper, we extensively investigate three typical solvable collective behaviors in globally coupled Stuart-Landau limit-cycle systems under mean-field feedback: incoherence, amplitude death, and locked states. In the thermodynamic limit of <inline-formula><tex-math id=\"M2\">begin{document}$Nrightarrowinfty$end{document}</tex-math><alternatives><graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"20-20230842_M2.jpg\"/><graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"20-20230842_M2.png\"/></alternatives></inline-formula>, the critical condition characterizing the transition from incoherence to synchronization is explicitly obtained via performing the linear stability of the incoherent states, it is found that the synchronization transition occurs at a smaller coupling strength when the strength of mean-field feedback is gradually enhanced; the stable regions of amplitude death are theoretically obtained via an analysis of the linear stability of coupled systems around the origin, it is unveiled that the presence of mean-field feedback is able to effectively eliminate the phenomenon of amplitude death in the coupled systems; furthermore, the existence of locked states is theoretically analyzed, and in particular the boundary of stable amplitude death region is re-derived from the self-consistent relation of the order parameter for the locked states. The study of this work reveals the key role of mean-field feedback in controlling the collective dynamics of coupled nonlinear systems, deepens the understanding of the impact of mean-field feedback technique on the coupling-induced collective behaviors, and is beneficial for us to further understand the emergence rules and the underlying mechanisms of self-organized behaviors in complex coupled systems.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136202323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
None Zheng Zhi-Yong, None Chen Li-Jie, None Xiang Lü, None Wang He, None Wang Yi-Ping
We propose a one-dimensional lattice theory scheme based on superconducting microwave cavities, which includes two different types of microwave cavity unit cells. The coupling between unit cells is controlled by flux qubits to simulate and study their topological insulator characteristics. Specifically, a one-dimensional superconducting microwave cavity lattice scheme with a p-wave superconducting pairing term is achieved by mapping the counter-rotating wave terms to the p-wave superconducting pairing term. We found that the p-wave superconducting pairing term can modulate the topological quantum state of the system, allowing for the creation of topological quantum information transmission channels with four edge states. In addition, when the p-wave superconducting pairing term and the nearest-neighbor interaction exist, we find that the energy band undergoes fluctuations, inducing the generation of new energy bands, but the degeneracy of the edge states remains stable, which can achieve multiple topological quantum state transmission paths. However, when its regulatory value exceeds the threshold, the energy gap of the system will close, causing the edge states to annihilate in new energy bands. Furthermore, when considering the existence of defects in the system, we found that when the strength of the defects are small, the edge state produces small fluctuations, but it can be clearly distinguished, indicating its robustness. When the strength of the defect exceeds the threshold, the edge state and energy band cause irregular fluctuations, allowing the edge state to integrate into the energy band. Our research results have important theoretical value and practical significance, and can be applied in quantum optics and quantum information processing in the future.
{"title":"Topological phase transitions and topological quantum states modulated by the counter-rotating wave terms in a one-dimensional superconducting microwave cavity lattice","authors":"None Zheng Zhi-Yong, None Chen Li-Jie, None Xiang Lü, None Wang He, None Wang Yi-Ping","doi":"10.7498/aps.73.20231321","DOIUrl":"https://doi.org/10.7498/aps.73.20231321","url":null,"abstract":"We propose a one-dimensional lattice theory scheme based on superconducting microwave cavities, which includes two different types of microwave cavity unit cells. The coupling between unit cells is controlled by flux qubits to simulate and study their topological insulator characteristics. Specifically, a one-dimensional superconducting microwave cavity lattice scheme with a p-wave superconducting pairing term is achieved by mapping the counter-rotating wave terms to the p-wave superconducting pairing term. We found that the p-wave superconducting pairing term can modulate the topological quantum state of the system, allowing for the creation of topological quantum information transmission channels with four edge states. In addition, when the p-wave superconducting pairing term and the nearest-neighbor interaction exist, we find that the energy band undergoes fluctuations, inducing the generation of new energy bands, but the degeneracy of the edge states remains stable, which can achieve multiple topological quantum state transmission paths. However, when its regulatory value exceeds the threshold, the energy gap of the system will close, causing the edge states to annihilate in new energy bands. Furthermore, when considering the existence of defects in the system, we found that when the strength of the defects are small, the edge state produces small fluctuations, but it can be clearly distinguished, indicating its robustness. When the strength of the defect exceeds the threshold, the edge state and energy band cause irregular fluctuations, allowing the edge state to integrate into the energy band. Our research results have important theoretical value and practical significance, and can be applied in quantum optics and quantum information processing in the future.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136203476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Small size metal-oxide-semiconductor field effect transistor (MOSFET), owing to their high theoretical efficiency and low production cost, have received much attention and are at the frontier of transistors. At present, their development is bottlenecked by physical limits due to equal scaling down of devices, which requires further improvement in terms of materials choice and device fabrication. As the MOSFET devices scale down to nanometer scale, on the one hand, the resulting short channel effect affects severely the thermal noise property; on the other hand, it makes the ratio of thermal noise in the gate, source, drain and substrate regions become higher and higher. However, the traditional thermal noise model mainly considers thermal noise of large-size devices, and its model does not consider the channel saturation region. In view of this, it is necessary to establish a small size MOSFET thermal noise model and analyze its characteristics.At present, there are some researches on MOSFET thermal noise, but they mainly focus on the thermal noise in channel region of large size nanoscale MOSFET. In the present work, according to the device structure and inherent thermal noise characteristics, we establish a thermal noise model for MOSFETs of 10 nm feature size. The model includes contributions of substrate region, gate-source-drain region, and channel region. In the channel region is also included the thermal noise related to the device saturation regime. Using such a model, the dependence of channel thermal noise and total thermal noise on the device bias condition and device parameters are investigated, evidencing the existence of thermal noise in the device saturation regime, which are consistent with the experimental results in the literature. The thermal noise increases with the gate voltage and source-drain voltage rising as the device structure shrinks. In a temperature range of 100－400 K, the thermal noise is basically on the order of 1021, indicating that the temperature has a great influence on the thermal noise. The thermal noise model established in this work can be applied to analyzing the noise performances of small size MOSFET devices, and the conclusions drawn from the present study are beneficial to improving the efficiency, lifetime, and response speed of MOSFETs on a nanometer scale.
{"title":"Analysis of thermal noise characteristics in 10nm metal oxide semiconductor field effect transistor","authors":"None Jia Xiao-Fei, None Wei Qun, None He Liang, None Zhang Wen-Peng, None Wu Zhen-Hua","doi":"10.7498/aps.72.20230661","DOIUrl":"https://doi.org/10.7498/aps.72.20230661","url":null,"abstract":"<sec>Small size metal-oxide-semiconductor field effect transistor (MOSFET), owing to their high theoretical efficiency and low production cost, have received much attention and are at the frontier of transistors. At present, their development is bottlenecked by physical limits due to equal scaling down of devices, which requires further improvement in terms of materials choice and device fabrication. As the MOSFET devices scale down to nanometer scale, on the one hand, the resulting short channel effect affects severely the thermal noise property; on the other hand, it makes the ratio of thermal noise in the gate, source, drain and substrate regions become higher and higher. However, the traditional thermal noise model mainly considers thermal noise of large-size devices, and its model does not consider the channel saturation region. In view of this, it is necessary to establish a small size MOSFET thermal noise model and analyze its characteristics.</sec><sec>At present, there are some researches on MOSFET thermal noise, but they mainly focus on the thermal noise in channel region of large size nanoscale MOSFET. In the present work, according to the device structure and inherent thermal noise characteristics, we establish a thermal noise model for MOSFETs of 10 nm feature size. The model includes contributions of substrate region, gate-source-drain region, and channel region. In the channel region is also included the thermal noise related to the device saturation regime. Using such a model, the dependence of channel thermal noise and total thermal noise on the device bias condition and device parameters are investigated, evidencing the existence of thermal noise in the device saturation regime, which are consistent with the experimental results in the literature. The thermal noise increases with the gate voltage and source-drain voltage rising as the device structure shrinks. In a temperature range of 100－400 K, the thermal noise is basically on the order of 10<sup>21</sup>, indicating that the temperature has a great influence on the thermal noise. The thermal noise model established in this work can be applied to analyzing the noise performances of small size MOSFET devices, and the conclusions drawn from the present study are beneficial to improving the efficiency, lifetime, and response speed of MOSFETs on a nanometer scale.</sec>","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136259097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
None Li Rui, None Xu Bang-Lin, None Zhou Jian-Fang, None Jiang En-Hua, None Wang Bing-Hong, None Yuan Wu-Jie
Experiments found that learning during wakefulness led to a net enhancement of synaptic strength, accompanied by the neural dynamical transition from tonic to bursting firing, while the net synaptic strength decreases to a baseline level during sleep, accompanied by the transition from bursting to tonic firing. In this paper, we provided a model of synaptic plasticity, which can realize synaptic strength changes and neural dynamical transitions for wakefulness-sleep cycle by using a coupled Hindmarsh-Rose neurons. Through numerical simulation and theoretical analysis, it was further found that, the average synaptic weight of the neural network can arrive to a stable value during either prolonged wakefulness or prolonged sleep, which depends on the ratio of some specific parameters in the model. Particularly, the synaptic weights exhibit a stable log-normal distribution observed in real neural systems, when the average synaptic weight arrives to the stable value. Moreover, the fluctuation of this weight distribution is positively correlated with the fluctuation of noise in the synaptic plasticity model. The provided model of the synaptic plasticity and the results of its dynamics can provide a theoretical reference for the physiological mechanism of synaptic plasticity and neuronal firings during the wakefulness-sleep cycle, and are expected to have potential applications in the development of therapeutic interventions for sleep disorders.
{"title":"Synaptic strength changes and neural dynamical transitions induced by a synaptic plasticity for wakefulness-sleep cycle","authors":"None Li Rui, None Xu Bang-Lin, None Zhou Jian-Fang, None Jiang En-Hua, None Wang Bing-Hong, None Yuan Wu-Jie","doi":"10.7498/aps.72.20231037","DOIUrl":"https://doi.org/10.7498/aps.72.20231037","url":null,"abstract":"Experiments found that learning during wakefulness led to a net enhancement of synaptic strength, accompanied by the neural dynamical transition from tonic to bursting firing, while the net synaptic strength decreases to a baseline level during sleep, accompanied by the transition from bursting to tonic firing. In this paper, we provided a model of synaptic plasticity, which can realize synaptic strength changes and neural dynamical transitions for wakefulness-sleep cycle by using a coupled Hindmarsh-Rose neurons. Through numerical simulation and theoretical analysis, it was further found that, the average synaptic weight of the neural network can arrive to a stable value during either prolonged wakefulness or prolonged sleep, which depends on the ratio of some specific parameters in the model. Particularly, the synaptic weights exhibit a stable log-normal distribution observed in real neural systems, when the average synaptic weight arrives to the stable value. Moreover, the fluctuation of this weight distribution is positively correlated with the fluctuation of noise in the synaptic plasticity model. The provided model of the synaptic plasticity and the results of its dynamics can provide a theoretical reference for the physiological mechanism of synaptic plasticity and neuronal firings during the wakefulness-sleep cycle, and are expected to have potential applications in the development of therapeutic interventions for sleep disorders.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135495557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The preparation of traditional organic-inorganic lead-halogen hybrid perovskite solar cells often requires strict nitrogen glove box conditions, hindering their industrial scalability. This study aimed to explore the development of a large-area perovskite film formation process and design a novel device structure to achieve a dual enhancement of module device efficiency and stability in a high humidity air environment (55%). High-quality perovskite thin films were successfully prepared by vacuum extraction in ambient air, followed by a double-end low-temperature photopolymerization process utilizing acrylate monomer molecules for inner encapsulation modification of the freshly formed perovskite thin films. The impact of these techniques on the photoelectric characteristics of perovskite thin films and devices was investigated. The results indicated that uniform and dense perovskite films could be achieved in ambient air with a pumping time of 60 seconds. By adjusting the concentration of ethylene glycol dimethacrylate monomer molecules used in the low-temperature photopolymerization process, surface defects on the perovskite film could be effectively controlled. The optimal concentration of 1 mg/ml resulted in perovskite films with optimal morphology and fluorescence intensity. Furthermore, rigid and flexible module devices (effective area: 18 cm²), based on the polymer inner encapsulation, demonstrated outstanding outdoor photoelectric conversion efficiencies of 19.51% and 18.17%, respectively (with the highest indoor low-light conversion efficiencies of 25.13% and 30.2%, respectively). Notably, the untreated flexible devices exhibited a significant decline in photoelectric conversion efficiency, falling below 50% of the initial value after one month of exposure to air. In contrast, devices incorporating the polymer inner encapsulation layer maintained over 90% of their original efficiency, highlighting their excellent humidity resistance stability. Moreover, the polymer encapsulation layer also greatly improved the bending stability of the flexible devices. This research paved avenue for the industrial-scale production of perovskite solar cells, addressing the challenges associated with humidity and large-area fabrication. The findings contribute to the advancement of perovskite solar cell technology, offering a pathway for high-efficiency and stable devices suitable for real-world applications.
{"title":"In Air High-Efficiency and Stable Perovskite Solar Cells Module Assisted by Polymer Internal Encapsulation","authors":"None Xu Jie, None Feng Ze-Hua, None Liu Bing-Ye, None Zhu Xin-Yi, None Dai Jin-Fei, None Dong Hua, None Wu Zhao-Xin","doi":"10.7498/aps.72.20231055","DOIUrl":"https://doi.org/10.7498/aps.72.20231055","url":null,"abstract":"The preparation of traditional organic-inorganic lead-halogen hybrid perovskite solar cells often requires strict nitrogen glove box conditions, hindering their industrial scalability. This study aimed to explore the development of a large-area perovskite film formation process and design a novel device structure to achieve a dual enhancement of module device efficiency and stability in a high humidity air environment (55%). High-quality perovskite thin films were successfully prepared by vacuum extraction in ambient air, followed by a double-end low-temperature photopolymerization process utilizing acrylate monomer molecules for inner encapsulation modification of the freshly formed perovskite thin films. The impact of these techniques on the photoelectric characteristics of perovskite thin films and devices was investigated. The results indicated that uniform and dense perovskite films could be achieved in ambient air with a pumping time of 60 seconds. By adjusting the concentration of ethylene glycol dimethacrylate monomer molecules used in the low-temperature photopolymerization process, surface defects on the perovskite film could be effectively controlled. The optimal concentration of 1 mg/ml resulted in perovskite films with optimal morphology and fluorescence intensity. Furthermore, rigid and flexible module devices (effective area: 18 cm²), based on the polymer inner encapsulation, demonstrated outstanding outdoor photoelectric conversion efficiencies of 19.51% and 18.17%, respectively (with the highest indoor low-light conversion efficiencies of 25.13% and 30.2%, respectively). Notably, the untreated flexible devices exhibited a significant decline in photoelectric conversion efficiency, falling below 50% of the initial value after one month of exposure to air. In contrast, devices incorporating the polymer inner encapsulation layer maintained over 90% of their original efficiency, highlighting their excellent humidity resistance stability. Moreover, the polymer encapsulation layer also greatly improved the bending stability of the flexible devices. This research paved avenue for the industrial-scale production of perovskite solar cells, addressing the challenges associated with humidity and large-area fabrication. The findings contribute to the advancement of perovskite solar cell technology, offering a pathway for high-efficiency and stable devices suitable for real-world applications.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135495749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
None Zhu Kai, None Huang Can, None Cao Bang-Jie, None Pan Yan-Fei, None Fan Ji-Yu, None Ma Chun-Lan, None Zhu Yan
Kitaev interactions, which are bond-related anisotropic interactions induced by spin-orbit coupling(SOC), may produce quantum spin liquid states in 2D magnetic hexagonal lattices such as RuCl3. Generally the strong SOC in these materials come from heavy metal elements such as Ru in RuCl3. In recent years, some related studies have shown the presence of Kitaev effects in some 2D monolayers of ortho-octahedral structures containing heavy ligand elements, such as CrGeTe3, CrSiTe3, and so on. However, there are relatively few reports on the Kitaev interactions in 2D monolayer 1T structures. In this paper, we have calculated and analysed the atomic and electronic structures of 1T-CoI2 and the Kitaev interactions contained therein by means of the first-principles calculation program VASP. The structure of 1T-CoI2 is a triangular lattice with an emphasis on the coordinating element I. The energy dispersion relation ES( q )=EN+S( q )-EN( q ) for the contained Kitaev action was isolated by calculating the energy dispersion relation EN( q ) for the spin-spiral of a monolayer CoI2 without SOC and the energy dispersion relation EN+S( q ) considering SOC using the generalised Bloch condition combined with the spin-spiral method. The parameters of the Heisenberg exchange interaction induced by the SOC were obtained by fitting the dispersion law of the ES( q ) to the Kitaev exchange interaction with the parameters of the Kitaev exchange interaction. The fitted curves obtained with the fitted parameters are in good agreement with the calculated values, indicating the accuracy of our calculations. Calculated fits show that the monolayer CoI2 is dominated by Heisenberg action, with the third nearest neighbour having the largest absolute value of J at -1.81 meV. In addition to this, there are strong Kitaev interactions in monolayer CoI2, where Γ1 reaches 1.09 meV. We predict that Kitaev interactions are universally applicable in transition metal triangular lattices with 1T structure. It is shown that CoI2 can be used as an alternative material for Kitaev and lays a theoretical foundation for exploring Kitaev interactions in other 2D magnetic materials.
{"title":"First-principles study of the role of Kitaev interaction in monolayer 1T-CoI<sub>2</sub>","authors":"None Zhu Kai, None Huang Can, None Cao Bang-Jie, None Pan Yan-Fei, None Fan Ji-Yu, None Ma Chun-Lan, None Zhu Yan","doi":"10.7498/aps.72.20230909","DOIUrl":"https://doi.org/10.7498/aps.72.20230909","url":null,"abstract":"Kitaev interactions, which are bond-related anisotropic interactions induced by spin-orbit coupling(SOC), may produce quantum spin liquid states in 2D magnetic hexagonal lattices such as RuCl<sub>3</sub>. Generally the strong SOC in these materials come from heavy metal elements such as Ru in RuCl<sub>3</sub>. In recent years, some related studies have shown the presence of Kitaev effects in some 2D monolayers of ortho-octahedral structures containing heavy ligand elements, such as CrGeTe<sub>3</sub>, CrSiTe<sub>3</sub>, and so on. However, there are relatively few reports on the Kitaev interactions in 2D monolayer 1T structures. In this paper, we have calculated and analysed the atomic and electronic structures of 1T-CoI<sub>2</sub> and the Kitaev interactions contained therein by means of the first-principles calculation program VASP. The structure of 1T-CoI<sub>2</sub> is a triangular lattice with an emphasis on the coordinating element I. The energy dispersion relation <i>E<sub>S</sub>( <b>q</b> )=E<sub>N+S</sub>( <b>q</b> )-E<sub>N</sub>( <b>q</b> )</i> for the contained Kitaev action was isolated by calculating the energy dispersion relation <i>E<sub>N</sub>( <b>q</b> )</i> for the spin-spiral of a monolayer CoI<sub>2</sub> without SOC and the energy dispersion relation <i>E<sub>N+S</sub>( <b>q</b> )</i> considering SOC using the generalised Bloch condition combined with the spin-spiral method. The parameters of the Heisenberg exchange interaction induced by the SOC were obtained by fitting the dispersion law of the <i>E<sub>S</sub>( <b>q</b> )</i> to the Kitaev exchange interaction with the parameters of the Kitaev exchange interaction. The fitted curves obtained with the fitted parameters are in good agreement with the calculated values, indicating the accuracy of our calculations. Calculated fits show that the monolayer CoI<sub>2</sub> is dominated by Heisenberg action, with the third nearest neighbour having the largest absolute value of J at -1.81 meV. In addition to this, there are strong Kitaev interactions in monolayer CoI<sub>2</sub>, where Γ<sub>1</sub> reaches 1.09 meV. We predict that Kitaev interactions are universally applicable in transition metal triangular lattices with 1T structure. It is shown that CoI<sub>2</sub> can be used as an alternative material for Kitaev and lays a theoretical foundation for exploring Kitaev interactions in other 2D magnetic materials.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135496009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Transition metal phthalocyanine molecules serve as building blocks for two-dimensional (2D) metal-organic frameworks with potential applications in optics, electronics, and spintronics. Previous theoretical studies predicted that a two-dimensional transition metal phthalocyanine framework with kagome lattice (kag-TMPc) has stable magnetically ordered properties, which are promising for spintronics and optoelectronics. However, there is a lack of studies on their heterojunctions, which can effectively tune the properties through interlayer coupling despite its weak nature. Here we use density functional theory (DFT) to calculate the electronic properties of eight representative 2D kag-TMPc vertical heterojunctions with two different stackings (AA and AB) and interlayer distances. We found that most of the kag-MnPc-based heterojunctions can maintain the electronic properties of monolayer materials with low bandgap. kag-MnPc/ZnPc are ferromagnetic semiconductors with magnetic exchange energy above 40 meV, regardless of stacking sequences; the electronic properties of kag-MnPc/MnPc heterojunctions change from magnetic half-metal to magnetic semiconductor during the transition from AA stacking to AB stacking. Interestingly, the AB stacked kag-CuPc/CoPc heterojunction is a ferromagnetic semiconductor, and the spin-polarized energy band arrangement changes with the layer spacing: when the layer spacing is at the equilibrium distance, the spin-up and spin-down energy bands are aligned as type II; when the layer spacing increases by 0.2 Å, the spin-up energy bands are aligned as type I, while the spin-down energy bands are aligned as type II energy bands. This distance-dependent spin properties can realize magnetic optoelectronic "switching" and has potential applications in new magnetic field modulated lectromagnetic and optoelectronic devices.
{"title":"Electronic Properties of Two-Dimensional Kagome Lattice Based on Transition Metal Phthalocyanine Heterojunctions","authors":"None Jiang Zhou, None Jiang Xue, None Zhao Ji-Jun","doi":"10.7498/aps.72.20230921","DOIUrl":"https://doi.org/10.7498/aps.72.20230921","url":null,"abstract":"Transition metal phthalocyanine molecules serve as building blocks for two-dimensional (2D) metal-organic frameworks with potential applications in optics, electronics, and spintronics. Previous theoretical studies predicted that a two-dimensional transition metal phthalocyanine framework with kagome lattice (kag-TMPc) has stable magnetically ordered properties, which are promising for spintronics and optoelectronics. However, there is a lack of studies on their heterojunctions, which can effectively tune the properties through interlayer coupling despite its weak nature. Here we use density functional theory (DFT) to calculate the electronic properties of eight representative 2D kag-TMPc vertical heterojunctions with two different stackings (AA and AB) and interlayer distances. We found that most of the kag-MnPc-based heterojunctions can maintain the electronic properties of monolayer materials with low bandgap. kag-MnPc/ZnPc are ferromagnetic semiconductors with magnetic exchange energy above 40 meV, regardless of stacking sequences; the electronic properties of kag-MnPc/MnPc heterojunctions change from magnetic half-metal to magnetic semiconductor during the transition from AA stacking to AB stacking. Interestingly, the AB stacked kag-CuPc/CoPc heterojunction is a ferromagnetic semiconductor, and the spin-polarized energy band arrangement changes with the layer spacing: when the layer spacing is at the equilibrium distance, the spin-up and spin-down energy bands are aligned as type II; when the layer spacing increases by 0.2 Å, the spin-up energy bands are aligned as type I, while the spin-down energy bands are aligned as type II energy bands. This distance-dependent spin properties can realize magnetic optoelectronic \"switching\" and has potential applications in new magnetic field modulated lectromagnetic and optoelectronic devices.","PeriodicalId":10252,"journal":{"name":"Chinese Physics","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135595469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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