This study integrates pedestrian flow characteristics to formulate a mesoscopic cellular automata model tailored for simulating evacuations in large-scale scenarios. Departing from the conventional planar grid cell division, the model employs road cell segmentation, thereby physically enlarging the dimensions of individual cells. This augmentation accommodates an increased occupancy of individuals per cell, representing pedestrian flow parameters within each cell through state variables. The source loading cell facilitates the simulation of pedestrian behavior transitioning from buildings to roads during an actual evacuation event, while the unloading cell situated at the exit removes evacuees from the system. The continuity equation for state transitions comprehensively encapsulates the dynamics of pedestrians throughout the evacuation process. Potential challenges in actual evacuation processes are identified through the simulation, offering valuable insights for improvement. This research aims to contribute to a more effective and informed approach to evacuation planning and management.
{"title":"Simulation method of urban evacuation based on mesoscopic cellular automata","authors":"Lu Wei, Wang Jing-Hui, Fang Zhi-ming, Mao Dun","doi":"10.7498/APS.70.20210018","DOIUrl":"https://doi.org/10.7498/APS.70.20210018","url":null,"abstract":"This study integrates pedestrian flow characteristics to formulate a mesoscopic cellular automata model tailored for simulating evacuations in large-scale scenarios. Departing from the conventional planar grid cell division, the model employs road cell segmentation, thereby physically enlarging the dimensions of individual cells. This augmentation accommodates an increased occupancy of individuals per cell, representing pedestrian flow parameters within each cell through state variables. The source loading cell facilitates the simulation of pedestrian behavior transitioning from buildings to roads during an actual evacuation event, while the unloading cell situated at the exit removes evacuees from the system. The continuity equation for state transitions comprehensively encapsulates the dynamics of pedestrians throughout the evacuation process. Potential challenges in actual evacuation processes are identified through the simulation, offering valuable insights for improvement. This research aims to contribute to a more effective and informed approach to evacuation planning and management.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"110 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76105482","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}
We generalize the gravitational form factor for chiral fermion in vacuum, which reproduces the well-known spin-vorticity coupling. We also calculate radiative correction to the gravitational form factors in quantum electrodynamics plasma. We find two structures in the form factors contributing to the scattering amplitude of fermion in vorticity field, one is from the fermon self-energy correction, pointing to suppression of spin-vorticity coupling in medium; the other strucutre comes from graviton-fermion vertex correction, which does not adopt potential interpretation, but corresponds to transition matrix element between initial and final states. Both structures contribute to chiral vortical effect. The net effect is that radiative correction enhances the chiral vortical effect. Our results claify the relation and difference between spin-vorticity coupling and chiral vortical effect from the perspective of form factors. We also discuss the application of the results in QCD plasma, indicating radiative correction might have an appreciable effect in spin polarization effect in heavy ion collisions.
{"title":"Medium Correction to Gravitational Form Factors","authors":"Shu Lin, Jiayuan Tian","doi":"10.7498/aps.72.20222473","DOIUrl":"https://doi.org/10.7498/aps.72.20222473","url":null,"abstract":"We generalize the gravitational form factor for chiral fermion in vacuum, which reproduces the well-known spin-vorticity coupling. We also calculate radiative correction to the gravitational form factors in quantum electrodynamics plasma. We find two structures in the form factors contributing to the scattering amplitude of fermion in vorticity field, one is from the fermon self-energy correction, pointing to suppression of spin-vorticity coupling in medium; the other strucutre comes from graviton-fermion vertex correction, which does not adopt potential interpretation, but corresponds to transition matrix element between initial and final states. Both structures contribute to chiral vortical effect. The net effect is that radiative correction enhances the chiral vortical effect. Our results claify the relation and difference between spin-vorticity coupling and chiral vortical effect from the perspective of form factors. We also discuss the application of the results in QCD plasma, indicating radiative correction might have an appreciable effect in spin polarization effect in heavy ion collisions.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88599214","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}
High-entropy alloys have broad application prospects in aviation,aerospace,military and other fields due to their excellent mechanical properties.Temperature is an important external factor affecting the shock response of high-entropy alloys.Molecular dynamics methods are used to investigate the effect of temperature on the shock response and plastic deformation mechanisms of CoCrFeMnNi high-entropy alloys.The effects of temperature on the atomic volume and the radial distribution function of CoCrFeMnNi high-entropy alloys are studied.Then,the piston method is used to generate shock waves in the sample to research the shock response of CoCrFeMnNi high-entropy alloys.The polyhedral template matching method is used to observe the evolution of atomic-scale defects during the shock compression.The results show that the shock pressure,the shock wave propagation velocity,and the shock-induced temperature rise decrease with the increase of the initial temperature.For example,when piston velocity Up=1.5 km/s,the shock pressure at an initial temperature of 1000 K decreased by 6.7% compared to that at 1 K.Moreover,the shock Hugoniot elastic limit decrease linearly with the increase of temperature.The Hugoniot Up- Us curve of CoCrFeMnNi HEA in the plastic stage can be linearly fitted by the formula Us=c0+sUp.c0 decreases with increasing temperature.With increasing shock intensities,CoCrFeMnNi high-entropy alloys undergo complex plastic deformation,including dislocation slip,phase transformation,deformation twinning,and shock-induced amorphization.At relatively high initial temperature,disordered clusters appear inside CoCrFeMnNi HEA,which together with the BCC structure transformed from FCC and disordered structure are significant dislocation nucleation sources.Compared with other elements,Mn element has the largest proportion (25.4%) in disordered clusters.Due to the large atomic volume and potential energy,large lattice distortion and local stress occur around the Mn-rich element,which provides dominant contribution to shock-induced plastic deformation.At high temperatures,the contribution of Fe element to plastic deformation is as important as that of Mn element.The research results contribute to a deep understanding of the shock-induced plasticity and deformation mechanisms of CoCrFeMnNi high-entropy alloys.
{"title":"Molecular dynamics study of the effect of temperature on the shock response and plastic deformation mechanism of CoCrFeMnNi high-entropy alloys","authors":"Wen Peng, Tao Gang","doi":"10.7498/aps.72.20221621","DOIUrl":"https://doi.org/10.7498/aps.72.20221621","url":null,"abstract":"High-entropy alloys have broad application prospects in aviation,aerospace,military and other fields due to their excellent mechanical properties.Temperature is an important external factor affecting the shock response of high-entropy alloys.Molecular dynamics methods are used to investigate the effect of temperature on the shock response and plastic deformation mechanisms of CoCrFeMnNi high-entropy alloys.The effects of temperature on the atomic volume and the radial distribution function of CoCrFeMnNi high-entropy alloys are studied.Then,the piston method is used to generate shock waves in the sample to research the shock response of CoCrFeMnNi high-entropy alloys.The polyhedral template matching method is used to observe the evolution of atomic-scale defects during the shock compression.The results show that the shock pressure,the shock wave propagation velocity,and the shock-induced temperature rise decrease with the increase of the initial temperature.For example,when piston velocity Up=1.5 km/s,the shock pressure at an initial temperature of 1000 K decreased by 6.7% compared to that at 1 K.Moreover,the shock Hugoniot elastic limit decrease linearly with the increase of temperature.The Hugoniot Up- Us curve of CoCrFeMnNi HEA in the plastic stage can be linearly fitted by the formula Us=c0+sUp.c0 decreases with increasing temperature.With increasing shock intensities,CoCrFeMnNi high-entropy alloys undergo complex plastic deformation,including dislocation slip,phase transformation,deformation twinning,and shock-induced amorphization.At relatively high initial temperature,disordered clusters appear inside CoCrFeMnNi HEA,which together with the BCC structure transformed from FCC and disordered structure are significant dislocation nucleation sources.Compared with other elements,Mn element has the largest proportion (25.4%) in disordered clusters.Due to the large atomic volume and potential energy,large lattice distortion and local stress occur around the Mn-rich element,which provides dominant contribution to shock-induced plastic deformation.At high temperatures,the contribution of Fe element to plastic deformation is as important as that of Mn element.The research results contribute to a deep understanding of the shock-induced plasticity and deformation mechanisms of CoCrFeMnNi high-entropy alloys.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"56 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73253429","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}
Fan Wen-Xin, Wang Min-Jie, Jiao Hao-Le, Lu Jia-Jin, Liu Hai-Long, Yang Zhi-Fang, Xi Meng-Qi, Li Shu-Jing, Wang Hai
Quantum communication holds promise for absolutely secure information transmission. However, the direct transmission distance of quantum states is limited by the no-cloning theorem and transmission loss. To overcome these problems, Duan et al. proposed a promising quantum repeater scheme, DLCZ protocol (for Duan, Lukin, Cirac, and Zoller, in 2001), in which linear optics and atomic ensembles are used to combine entanglement generation and quantum memory into a single node. A quantum memory with highly retrieval efficiency is beneficial to increase the rate of entanglement swapping, achieving high-speed entanglement distribution. Up to now, high-efficiency quantum memories have been realized using high-optical-depth atomic ensembles or by coupling atomic ensembles with a medium-finesse optical cavity. However, the effect of the waist ratio of read beam and anti-Stokes photon modes on intrinsic retrieval efficiency has not been studied in detail. Here, we study the dependence of intrinsic retrieval efficiency on the waist ratio of read beam and anti-Stokes photon modes in cavity-enhanced quantum memory.In this work, a 87Rb atomic ensemble, that is placed at the center of a passively stabilized polarization interferometer (BD1,2), is used as quantum memory. Firstly, the ensemble is captured through magneto-optical trapping (MOT) and prepared to the Zeeman sub-level of ground state $|5{S_{1/2}},F = 1,m = 0rangle$. Then, a weak write pulse, with frequency red-detuned from the $|5{S_{1/2}},F = 1,m = 0rangle$$ to |5{P_{1/2}},F' = 1,m = 1rangle $ transition by 110 MHz, illuminates the atoms and induces spontaneous Raman scattering out a Stokes photon. In this regime of weak excitation, the detection of a Stokes photon heralds the storage of a single spin wave $|5{S_{1/2}},F = 1,m = 0rangle$$ leftrightarrow |5{S_{1/2}},F = 2,m = 0rangle $ ($|5{S_{1/2}},F = 1,m = 0rangle$$leftrightarrow |5{S_{1/2}},F = 2,m = 2rangle $) distributed among the whole ensemble. After a programmable delay, a read pulse, red-detuned from the $|5{S_{1/2}},F = 2,m = 0rangle to |5{P_{1/2}},F' = 2,m = - 1rangle $ transition by 110MHz, transfer this spin wave into an anti-Stokes photon. We detect the Stokes photons and anti-Stokes photons with polarization ${sigma ^ + }$, which means all the spin-wave are stored in a magnetic-field-insensitive state to reduce the decoherence caused by the stray magnetic fields. In order to increase the intrinsic retrieval efficiency, the atomic ensemble is placed in a ring cavity. The cavity length is 4 m, the finesse is measured to be ~15, and the escape efficiency of ring cavity is 52.9%. Both Stokes and anti-Stokes photon qubits are required to resonate with the ring cavity. To meet this requirement, a cavity-locking beam is injected into the cavity to stabilize the cavity length using a Pound-Drever-Hall locking scheme. Finally, we fixed the Stokes (anti-Stokes) photon modes waist and changed the waist ratio by changing the write beam (read beam)
量子通信有望实现绝对安全的信息传输。然而，量子态的直接传输距离受到不可克隆定理和传输损耗的限制。为了克服这些问题，Duan等人提出了一种很有前途的量子中继器方案，DLCZ协议(为Duan、Lukin、Cirac和Zoller于2001年提出)，其中使用线性光学和原子系综将纠缠产生和量子存储结合到单个节点中。具有高检索效率的量子存储器有利于提高纠缠交换速率，实现高速纠缠分配。到目前为止，高效量子存储主要是利用高光深原子系综或将原子系综与中等精细度的光腔耦合实现的。然而，读光束和反斯托克斯光子模式腰比对本征检索效率的影响尚未得到详细的研究。本文研究了腔增强量子存储中读光束和反stokes光子模式腰比对本征检索效率的影响。在这项工作中，放置在被动稳定偏振干涉仪(BD1,2)中心的87Rb原子系综被用作量子存储器。首先，通过磁光捕获(MOT)捕获该系综，并将其制备到基态的塞曼亚能级$|5{S_{1/2}},F = 1,m = 0rangle$。然后，一个频率从$|5{S_{1/2}},F = 1,m = 0rangle$$ to |5{P_{1/2}},F' = 1,m = 1rangle $跃迁红失调谐110兆赫兹的弱写入脉冲，照亮原子并诱导自发拉曼散射出一个斯托克斯光子。在这种弱激发状态下，斯托克斯光子的探测预示着单个自旋波$|5{S_{1/2}},F = 1,m = 0rangle$$ leftrightarrow |5{S_{1/2}},F = 2,m = 0rangle $ ($|5{S_{1/2}},F = 1,m = 0rangle$$leftrightarrow |5{S_{1/2}},F = 2,m = 2rangle $)分布在整个系综中的存储。经过可编程延迟后，读取脉冲，从$|5{S_{1/2}},F = 2,m = 0rangle to |5{P_{1/2}},F' = 2,m = - 1rangle $跃迁红失调谐110MHz，将该自旋波转换为反斯托克斯光子。我们检测到Stokes光子和反Stokes光子的极化${sigma ^ + }$，这意味着所有的自旋波都以磁场不敏感的状态存储，以减少杂散磁场引起的退相干。为了提高本征检索效率，原子系综被放置在环形腔中。环形腔长度为4 m，精密度为15，环形腔的逃逸效率为52.9%. Both Stokes and anti-Stokes photon qubits are required to resonate with the ring cavity. To meet this requirement, a cavity-locking beam is injected into the cavity to stabilize the cavity length using a Pound-Drever-Hall locking scheme. Finally, we fixed the Stokes (anti-Stokes) photon modes waist and changed the waist ratio by changing the write beam (read beam) waist.The experiment result show that when the waist ratio of read beam and anti-Stokes photon modes is 3, the intrinsic retrieval efficiency is up to 68.9±1.6% and normalized cross-correlation function g(2) reaches 26.5±1.9. We built a theoretical model, the intrinsic retrieval efficiency increases with the rise of the waist ratio, which show that the intrinsic retrieval efficiency is up to the peak when the waist ratio is 3, and the intrinsic retrieval efficiency tends to be stable when the waist ratio continues to increase. The experiment agrees with the theory. In the future, we will improve the intrinsic retrieval efficiency by enhance the fineness of the optical cavity with optimizing the cavity parameters.
{"title":"Dependence of retrieval efficiency on the waist ratio of read beam and anti-Stokes photon modes in cavity-enhanced quantum memory","authors":"Fan Wen-Xin, Wang Min-Jie, Jiao Hao-Le, Lu Jia-Jin, Liu Hai-Long, Yang Zhi-Fang, Xi Meng-Qi, Li Shu-Jing, Wang Hai","doi":"10.7498/aps.72.20230966","DOIUrl":"https://doi.org/10.7498/aps.72.20230966","url":null,"abstract":"Quantum communication holds promise for absolutely secure information transmission. However, the direct transmission distance of quantum states is limited by the no-cloning theorem and transmission loss. To overcome these problems, Duan et al. proposed a promising quantum repeater scheme, DLCZ protocol (for Duan, Lukin, Cirac, and Zoller, in 2001), in which linear optics and atomic ensembles are used to combine entanglement generation and quantum memory into a single node. A quantum memory with highly retrieval efficiency is beneficial to increase the rate of entanglement swapping, achieving high-speed entanglement distribution. Up to now, high-efficiency quantum memories have been realized using high-optical-depth atomic ensembles or by coupling atomic ensembles with a medium-finesse optical cavity. However, the effect of the waist ratio of read beam and anti-Stokes photon modes on intrinsic retrieval efficiency has not been studied in detail. Here, we study the dependence of intrinsic retrieval efficiency on the waist ratio of read beam and anti-Stokes photon modes in cavity-enhanced quantum memory.In this work, a 87Rb atomic ensemble, that is placed at the center of a passively stabilized polarization interferometer (BD1,2), is used as quantum memory. Firstly, the ensemble is captured through magneto-optical trapping (MOT) and prepared to the Zeeman sub-level of ground state $|5{S_{1/2}},F = 1,m = 0rangle$. Then, a weak write pulse, with frequency red-detuned from the $|5{S_{1/2}},F = 1,m = 0rangle$$ to |5{P_{1/2}},F' = 1,m = 1rangle $ transition by 110 MHz, illuminates the atoms and induces spontaneous Raman scattering out a Stokes photon. In this regime of weak excitation, the detection of a Stokes photon heralds the storage of a single spin wave $|5{S_{1/2}},F = 1,m = 0rangle$$ leftrightarrow |5{S_{1/2}},F = 2,m = 0rangle $ ($|5{S_{1/2}},F = 1,m = 0rangle$$leftrightarrow |5{S_{1/2}},F = 2,m = 2rangle $) distributed among the whole ensemble. After a programmable delay, a read pulse, red-detuned from the $|5{S_{1/2}},F = 2,m = 0rangle to |5{P_{1/2}},F' = 2,m = - 1rangle $ transition by 110MHz, transfer this spin wave into an anti-Stokes photon. We detect the Stokes photons and anti-Stokes photons with polarization ${sigma ^ + }$, which means all the spin-wave are stored in a magnetic-field-insensitive state to reduce the decoherence caused by the stray magnetic fields. In order to increase the intrinsic retrieval efficiency, the atomic ensemble is placed in a ring cavity. The cavity length is 4 m, the finesse is measured to be ~15, and the escape efficiency of ring cavity is 52.9%. Both Stokes and anti-Stokes photon qubits are required to resonate with the ring cavity. To meet this requirement, a cavity-locking beam is injected into the cavity to stabilize the cavity length using a Pound-Drever-Hall locking scheme. Finally, we fixed the Stokes (anti-Stokes) photon modes waist and changed the waist ratio by changing the write beam (read beam) ","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"29 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72702810","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}
Di Shu-Hong, Zhang Yang, Yang Hui-Jing, Cui Nai-Zhong, Li Yan-Kun, Liu Hui-Yuan, Li Ling-Li, Shi Feng-Liang, Jia Yu-Xuan
Because of the difficulty in measuring the cluster isotope displacement and identifying its causes, the resonance dissociation spectra, the moment shift and Zeeman energy shift of isotope cluster 87,85Rbn(n=1,2, 3,..., 13) are obtained by the combination of optical magnetic resonance and thermal dissociation techniques in this study. The quantitative calculation is carried out based on the conceptual model of the giant atom, and the results are in strict agreement with the measured results, which shows that rubidium clusters can be analyzed as giant-like atoms. Furthermore, 5s electron shell level structure of the rubidium cluster 87,85Rbn(n=1,2, 3,..., 92) is calculated using Zeeman level interval model. It is found that the main order and step distance of the 5s electron shell structure are similar to those of 3s single electron shell structure of sodium cluster in spherical symmetric. It is confirmed that the structure of the 5s electron shell of the rubidium cluster is determined by the largest energy gap of total Zeeman levels and the characteristic peaks of odd and even alternating and anomalous magnetic moments of special numbers such as n=2 are caused by the intrinsic properties of electrons and molecular structures. It is also found that 87Rbn and 85Rbn level shell structure is strictly consistent with the ratio of 3/2 magnitude relationship, and there are abnormal differences in spectral center frequency and broadening, which may be directly related to the 85,87Rb nuclide on the closed surface of the core-shell.
{"title":"Quantitative study on isotope effect of rubidium clusters","authors":"Di Shu-Hong, Zhang Yang, Yang Hui-Jing, Cui Nai-Zhong, Li Yan-Kun, Liu Hui-Yuan, Li Ling-Li, Shi Feng-Liang, Jia Yu-Xuan","doi":"10.7498/aps.72.20230778","DOIUrl":"https://doi.org/10.7498/aps.72.20230778","url":null,"abstract":"Because of the difficulty in measuring the cluster isotope displacement and identifying its causes, the resonance dissociation spectra, the moment shift and Zeeman energy shift of isotope cluster 87,85Rbn(n=1,2, 3,..., 13) are obtained by the combination of optical magnetic resonance and thermal dissociation techniques in this study. The quantitative calculation is carried out based on the conceptual model of the giant atom, and the results are in strict agreement with the measured results, which shows that rubidium clusters can be analyzed as giant-like atoms. Furthermore, 5s electron shell level structure of the rubidium cluster 87,85Rbn(n=1,2, 3,..., 92) is calculated using Zeeman level interval model. It is found that the main order and step distance of the 5s electron shell structure are similar to those of 3s single electron shell structure of sodium cluster in spherical symmetric. It is confirmed that the structure of the 5s electron shell of the rubidium cluster is determined by the largest energy gap of total Zeeman levels and the characteristic peaks of odd and even alternating and anomalous magnetic moments of special numbers such as n=2 are caused by the intrinsic properties of electrons and molecular structures. It is also found that 87Rbn and 85Rbn level shell structure is strictly consistent with the ratio of 3/2 magnitude relationship, and there are abnormal differences in spectral center frequency and broadening, which may be directly related to the 85,87Rb nuclide on the closed surface of the core-shell.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"26 9","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72409684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wang Li-na, Zhao Xing-Yu, Shang Jie-Ying, Zhou Heng-Wei
Monohydroxy alcohol has a Debye relaxation process that other liquids usually do not have, and with the development of research, some new phenomena and new problems related to the process have been gradually discovered, deepening the understanding of material structure and dynamics. In order to further investigate the dynamics of Debye relaxation processes and the influence of molecular constitutions on them, the Debye processes of three primary alcohols without branched chains or side groups are studied by dielectric spectroscopy method, and some important information of the processes are revealed. A number of dynamic parameters of Debye relaxation in n-propanol, n-butanol and n-octanol almost all increase linearly with the rising number of carbon atoms in the molecules, which include the characteristic temperature, the reciprocal of Vogel-Fulcher-Tammann (VFT) temperature and the strength parameter of Debye processes as well as the activation energy and the logarithm of the intrinsic vibration frequency of relaxation units under high temperature limit. However, the values of VFT temperatures change little and have consistency, illustrating that the relaxation units of Debye processes in these three monohydroxy alcohols should be the same and further verifying the view that the Debye relaxation originates from the hydroxyl groups in hydrogen bonded molecular chains. Comparing Boiling temperatures and melting temperatures of those samples with the evolution of the above activation energy, it is shown that there is a positive correlation between the interaction among hydrogen bonds and the whole one among molecules. In addition, combined the information of the strength parameter with relevant theories, a possible perspective is gained for further investigation of liquid fragility. The comparison of those three samples with ethanol displays that the degree of separation of Debye relaxation and α relaxation is influenced by the molecular chain length, which could provide a breakthrough point to explore Debye relaxation. These results in this paper will promote further understanding and research of Debye relaxation in monohydroxy alcohols, and also provide experimental information for relevant theories.
{"title":"Measurement and Analysis of Debye Relaxation dynamics of n-propanol, n-butanol and n-octanol","authors":"Wang Li-na, Zhao Xing-Yu, Shang Jie-Ying, Zhou Heng-Wei","doi":"10.7498/aps.72.20221856","DOIUrl":"https://doi.org/10.7498/aps.72.20221856","url":null,"abstract":"Monohydroxy alcohol has a Debye relaxation process that other liquids usually do not have, and with the development of research, some new phenomena and new problems related to the process have been gradually discovered, deepening the understanding of material structure and dynamics. In order to further investigate the dynamics of Debye relaxation processes and the influence of molecular constitutions on them, the Debye processes of three primary alcohols without branched chains or side groups are studied by dielectric spectroscopy method, and some important information of the processes are revealed. A number of dynamic parameters of Debye relaxation in n-propanol, n-butanol and n-octanol almost all increase linearly with the rising number of carbon atoms in the molecules, which include the characteristic temperature, the reciprocal of Vogel-Fulcher-Tammann (VFT) temperature and the strength parameter of Debye processes as well as the activation energy and the logarithm of the intrinsic vibration frequency of relaxation units under high temperature limit. However, the values of VFT temperatures change little and have consistency, illustrating that the relaxation units of Debye processes in these three monohydroxy alcohols should be the same and further verifying the view that the Debye relaxation originates from the hydroxyl groups in hydrogen bonded molecular chains. Comparing Boiling temperatures and melting temperatures of those samples with the evolution of the above activation energy, it is shown that there is a positive correlation between the interaction among hydrogen bonds and the whole one among molecules. In addition, combined the information of the strength parameter with relevant theories, a possible perspective is gained for further investigation of liquid fragility. The comparison of those three samples with ethanol displays that the degree of separation of Debye relaxation and α relaxation is influenced by the molecular chain length, which could provide a breakthrough point to explore Debye relaxation. These results in this paper will promote further understanding and research of Debye relaxation in monohydroxy alcohols, and also provide experimental information for relevant theories.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"50 6 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72830832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the continuous development of CMOS technology, the feature size of MOSFETs is continuously shrunk, the short channel effects become more and more serious, which makes the static power consumption increase and now the static power consumption becomes the main source of the power consumption of the integrated circuits. At present, the performance of CMOS binary logic processors is nearly reaching the bottleneck; therefore the study of ternary logic becomes a research hotspot to promote the development of high performance and low power integrated circuits. Compared with binary logic, ternary logic possesses stronger data expression ability, which can not only improve the data density, but also reduce the circuit power consumption and the system complexity. However, using binary devices to build ternary logic circuits requires a large number of components, and even requires the passive components, which cannot exploit the advantages of ternary logic. The other method of implementing ternary logic is through the utilization of innovative two-dimensional materials. This method requires a small number of components and obviates the need for passive components, but it faces the problem that the fabrication process is not mature and can’t be mass-produced. To solve these issues, this paper combines the tunneling and the drift diffusion mechanism, proposed tunneling metal-oxide-semiconductor field-effect transistor (TMOSFET) which three-state characteristics make it highly suitable for ternary logic design. Compared with other ternary logic schemes, the ternary inverter based on TMOSFET has the same circuit structure with binary inverter, which can simplify the circuit design. In this paper, the operational mechanism of this ternary inverter is studied, and the condition of three-state output of inverter is analyzed. It is found that when the operating voltage VDD and the device turning voltage Vturn satisfy VDD/Vturn≈1.4, the input voltage ranges of the three output states are equivalent. In addition, the impact of TMOSFET transfer characteristic on this ternary inverter is also analyzed. This has certain reference significance for the future design and research of ternary logic circuits.
{"title":"A Novel TMOSFET Ternary Inverter Based on Hybrid Conduction Mechanism","authors":"Ma Xin, Lu Bin, Dong Linpeng, MiaoYuanhao","doi":"10.7498/aps.72.20230819","DOIUrl":"https://doi.org/10.7498/aps.72.20230819","url":null,"abstract":"With the continuous development of CMOS technology, the feature size of MOSFETs is continuously shrunk, the short channel effects become more and more serious, which makes the static power consumption increase and now the static power consumption becomes the main source of the power consumption of the integrated circuits. At present, the performance of CMOS binary logic processors is nearly reaching the bottleneck; therefore the study of ternary logic becomes a research hotspot to promote the development of high performance and low power integrated circuits. Compared with binary logic, ternary logic possesses stronger data expression ability, which can not only improve the data density, but also reduce the circuit power consumption and the system complexity. However, using binary devices to build ternary logic circuits requires a large number of components, and even requires the passive components, which cannot exploit the advantages of ternary logic. The other method of implementing ternary logic is through the utilization of innovative two-dimensional materials. This method requires a small number of components and obviates the need for passive components, but it faces the problem that the fabrication process is not mature and can’t be mass-produced. To solve these issues, this paper combines the tunneling and the drift diffusion mechanism, proposed tunneling metal-oxide-semiconductor field-effect transistor (TMOSFET) which three-state characteristics make it highly suitable for ternary logic design. Compared with other ternary logic schemes, the ternary inverter based on TMOSFET has the same circuit structure with binary inverter, which can simplify the circuit design. In this paper, the operational mechanism of this ternary inverter is studied, and the condition of three-state output of inverter is analyzed. It is found that when the operating voltage VDD and the device turning voltage Vturn satisfy VDD/Vturn≈1.4, the input voltage ranges of the three output states are equivalent. In addition, the impact of TMOSFET transfer characteristic on this ternary inverter is also analyzed. This has certain reference significance for the future design and research of ternary logic circuits.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"14 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72836894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The optimal selection of parameters in practical quantum key distribution can greatly improve the key generation rate and maximum transmission distance of the system. Due to the high cost of global search algorithm, local search algorithm is widely used. However, there are two vulnerabilities in local search algorithm, one is that the solution obtained is not always the global optimal solution, the other is that the effectiveness of the algorithm is greatly dependent on the choice of initial value. It is different from the previous article that this paper uses the Monte Carlo method to prove whether the key generation rate function is convex, and also simulates and analyzes the projection of key generation rate function on each dimension of the parameter. In order to eliminate the effect of the initial value, this paper proposes the particle swarm local search optimization algorithm which is combining particle swarm optimization algorithm and local search algorithm. The first step is using the particle swarm optimization to find a valid parameter which leads to nonzero key generation rate, the second step is using the parameter as the initial value of local search algorithm to derive the global optimal solution. Then, the two algorithms are simulated and compared. The results show that the key generation rate function is non-convex because it does not satisfy the definition of a convex function, however, since the key generation rate function has only one non-zero stagnation point, the LSA algorithm can still obtain the global optimal solution with a proper initial value, when the transmission distance is relatively long, the local search algorithm is invalid because it is difficult to obtain an effective initial value by random value method. Particle swarm optimization algorithm can overcome this shortcoming and improve the maximum transmission distance of the system at the cost of slightly increasing the complexity of the algorithm.
{"title":"Improved parameter optimization method for measurement device independent protocol","authors":"Zhou Jiang-Ping, Zhou Yuan-Yuan, Zhou Xue-Jun","doi":"10.7498/aps.72.20230179","DOIUrl":"https://doi.org/10.7498/aps.72.20230179","url":null,"abstract":"The optimal selection of parameters in practical quantum key distribution can greatly improve the key generation rate and maximum transmission distance of the system. Due to the high cost of global search algorithm, local search algorithm is widely used. However, there are two vulnerabilities in local search algorithm, one is that the solution obtained is not always the global optimal solution, the other is that the effectiveness of the algorithm is greatly dependent on the choice of initial value. It is different from the previous article that this paper uses the Monte Carlo method to prove whether the key generation rate function is convex, and also simulates and analyzes the projection of key generation rate function on each dimension of the parameter. In order to eliminate the effect of the initial value, this paper proposes the particle swarm local search optimization algorithm which is combining particle swarm optimization algorithm and local search algorithm. The first step is using the particle swarm optimization to find a valid parameter which leads to nonzero key generation rate, the second step is using the parameter as the initial value of local search algorithm to derive the global optimal solution. Then, the two algorithms are simulated and compared. The results show that the key generation rate function is non-convex because it does not satisfy the definition of a convex function, however, since the key generation rate function has only one non-zero stagnation point, the LSA algorithm can still obtain the global optimal solution with a proper initial value, when the transmission distance is relatively long, the local search algorithm is invalid because it is difficult to obtain an effective initial value by random value method. Particle swarm optimization algorithm can overcome this shortcoming and improve the maximum transmission distance of the system at the cost of slightly increasing the complexity of the algorithm.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"91 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74644463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liu Zhong-Lei, Cao Jin-Ming, Wang Zhi, Zhao Yu-Hong
The perovskite crystal structure determines the appearance of ferroelectricity and the determination of the polarization direction of ferroelectric ceramics. When the polarization direction has a certain order, different domain structures will combine to form a multiparticle system with a specific morphology, the topological structures that exist in ferroelectrics. In this study, the domain structure of potassium sodium niobate (K0.5Na0.5NbO3) thin films under different hysteresis electric fields and thicknesses was observed by the phase field method. According to the different switching paths of the domain structure under the electric field, the domain is divided into fast and slow switching process. Based on this, a method is proposed to first determine the domain switching state of the desired experiment and then conduct directional observation. Through the analysis of the domain structures combined with the polarization vector, a clear multi-domain combined vortex-antivortex pair topological structure was observed for the first time in K0.5Na0.5NbO3 films. The vortex structure was further analyzed for its switching process, and it was observed that this vortex topological microstructure can make the domain more likely to switch, so that more small-scale polarization vectors can be ordered to form the desired multiparticle system topology. This polarization vector ordering is similar to the microscopic phase boundary formed by the specific polarization directions on both sides of the morphotropic phase boundary (MPB) for the improvement of the dielectric properties of ferroelectric materials.
{"title":"Exploring Ferroelectric Vortex Topology and morphotropic Phase Boundaries by Phase Field Method","authors":"Liu Zhong-Lei, Cao Jin-Ming, Wang Zhi, Zhao Yu-Hong","doi":"10.7498/aps.72.20221898","DOIUrl":"https://doi.org/10.7498/aps.72.20221898","url":null,"abstract":"The perovskite crystal structure determines the appearance of ferroelectricity and the determination of the polarization direction of ferroelectric ceramics. When the polarization direction has a certain order, different domain structures will combine to form a multiparticle system with a specific morphology, the topological structures that exist in ferroelectrics. In this study, the domain structure of potassium sodium niobate (K0.5Na0.5NbO3) thin films under different hysteresis electric fields and thicknesses was observed by the phase field method. According to the different switching paths of the domain structure under the electric field, the domain is divided into fast and slow switching process. Based on this, a method is proposed to first determine the domain switching state of the desired experiment and then conduct directional observation. Through the analysis of the domain structures combined with the polarization vector, a clear multi-domain combined vortex-antivortex pair topological structure was observed for the first time in K0.5Na0.5NbO3 films. The vortex structure was further analyzed for its switching process, and it was observed that this vortex topological microstructure can make the domain more likely to switch, so that more small-scale polarization vectors can be ordered to form the desired multiparticle system topology. This polarization vector ordering is similar to the microscopic phase boundary formed by the specific polarization directions on both sides of the morphotropic phase boundary (MPB) for the improvement of the dielectric properties of ferroelectric materials.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"25 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74000656","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}
Heng-Di Wen, Yue Liu, Liang Zhen, Yang Li, Cheng-Yan Xu
Two-dimensional material heterojunction device with unique photoelectric properties due to its nanoscale thickness and van der Waals contact surface. In this paper, a MoS2/MoTe2 vertical vdWs heterojunction device with Gate-tunable is constructed. The Kelvin probe force microscopy (KPFM) technology is combined with the electric transport measurement technology, which reveals the charge transport behavior of the MoS2/MoTe2 heterojunction under dark and light conditions, including the bipolarity characteristics of the transition from n-n+ junction to p-n junction. This paper comprehensively and systematically explains the charge transport mechanism of heterojunction, including the charge transmission process of n-n+ junction and p-n junction under positive and negative bias conditions, the transformation of nodule behavior with gate voltage, the influence of barriers on charge transmission, the different rectification characteristics between n-n+ junction and p-n junction, the major role of source and leakage bias voltage on band tunneling, and the influence of photogenerated carriers on electrical transmission. The method in this paper can be generalized to other two-dimensional heterojunction systems and provides an important reference and reference for improving the performance of two-dimensional semiconductor devices and their applications in the future.
{"title":"Charge transmission of MoS2/MoTe2 vertical heterojunction and it's modulation","authors":"Heng-Di Wen, Yue Liu, Liang Zhen, Yang Li, Cheng-Yan Xu","doi":"10.7498/aps.72.20221768","DOIUrl":"https://doi.org/10.7498/aps.72.20221768","url":null,"abstract":"Two-dimensional material heterojunction device with unique photoelectric properties due to its nanoscale thickness and van der Waals contact surface. In this paper, a MoS2/MoTe2 vertical vdWs heterojunction device with Gate-tunable is constructed. The Kelvin probe force microscopy (KPFM) technology is combined with the electric transport measurement technology, which reveals the charge transport behavior of the MoS2/MoTe2 heterojunction under dark and light conditions, including the bipolarity characteristics of the transition from n-n+ junction to p-n junction. This paper comprehensively and systematically explains the charge transport mechanism of heterojunction, including the charge transmission process of n-n+ junction and p-n junction under positive and negative bias conditions, the transformation of nodule behavior with gate voltage, the influence of barriers on charge transmission, the different rectification characteristics between n-n+ junction and p-n junction, the major role of source and leakage bias voltage on band tunneling, and the influence of photogenerated carriers on electrical transmission. The method in this paper can be generalized to other two-dimensional heterojunction systems and provides an important reference and reference for improving the performance of two-dimensional semiconductor devices and their applications in the future.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"59 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73092164","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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