物理学报最新文献

{"title":"Dissipation-Induced Recurrence of Non-Hermitian Edge Burst","authors":"Ren Cui-Cui, Yin Xiang-Guo","doi":"10.7498/aps.72.20230338","DOIUrl":"https://doi.org/10.7498/aps.72.20230338","url":null,"abstract":"In quantum mechanics, the Hermitian Hamiltonian is generally used to describe the ideal closed quantum system, but in reality, the physical system is closely related to the environment, and the open quantum system coupled to the environment can be described by the equivalent non-Hermitian Hamiltonian to a certain extent. Among them, the dissipation intensity is closely related to the dynamic properties of non-Hermitian quantum systems. Therefore, it is of great practical significance to study how dissipation affects particle loss. In this paper, the dynamic law related to dissipation intensity in one-dimensional non-Hermitian systems under open boundary conditions is studied, and it is found that dissipation can induce the recurrence of edge burst. After the time-dependent evolution of the particles in the one-dimensional non-Hermitian dissipative lattice system with open boundary conditions, there is an edge burst in the system, that is, there is a large probability of particle loss at the edge, and the edge burst disappears after increasing the intensity of intracellular transition. It is found that if the dissipation intensity is increased or decreased, the edge burst will reappear. This kind of reappearance is different from the original edge burst, which is mainly manifested in the loss probability distribution of particles from the edge distribution to the volume distribution, which is due to the different probability of particle motion direction in the two cases. Under the re-induced edge burst, the particles move from the initial position to the left and right directions, and the left side rebounds after reaching the boundary, forming a more obvious loss probability at the edge and gradually decreasing to the body area. In the original edge burst, the probability of particles only moving to the left is larger, and the 'trapped' is completely dissipated at the edge, forming a distribution with an independent loss peak at the edge, the movement to the left is due to due to the non-Hermitian skin effect. The deeper reason for different movement directions is related to the defect of non-Hermitian system far from parity-time symmetry breaking. Under the parameter near the parity-time symmetry breaking defect, the loss probability of the particle is unilateral distribution, and the loss probability of the particle moving to both sides is bilateral distribution when it is far away. This is the description of the dissipation-induced edge burst recurrence phenomenon and its characteristics. In addition, this paper also studies the influence of impurity barrier on the probability distribution of particle loss in non-Hermitian dynamics. The results show that placing a small barrier on the non-dissipative A-site can obviously hinder the particle motion, and when the barrier increases to a certain height, its influence on the particle motion tends to be unchanged. And the barrier at the dissipative B lattice has little effect on the dynamics.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"16 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90132965","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}

{"title":"Soliton Solutions of the Spin-Orbit Coupled Binary Bose-Einstein Condensate System","authors":"Li Xin-Yue, Qi Juan-Juan, Zhao Dun, Liu Wu-ming","doi":"10.7498/aps.72.20222319","DOIUrl":"https://doi.org/10.7498/aps.72.20222319","url":null,"abstract":"In a quantum system with spin, spin-orbit coupling is manifested by linking the spin angular momentum of a particle with its orbital angular momentum, which leads to many exotic phenomena. The experimental realization of synthetic spin-orbit coupling effects in ultra-cold atomic systems provides a completely new platform for exploring quantum simulations. In a spinor Bose-Einstein condensate, the spin-orbit coupling can change the properties of the system significantly, which offers a great opportunity to investigate the influence of spin-orbit coupling to the quantum state at the macroscopic level. As typical states of macroscopic quantum effects, solitons in spin-orbit coupled Bose-Einstein condensates can be manipulated by spin-orbit coupling directly, this makes the study on spin-orbit coupled Bose-Einstein condensates become one of the hottest topics in the research of ultracold atomic physics in recent years. This paper investigates exact vector soliton solutions of the Gross-Pitaevskii equation for the one-dimensional spin-orbit coupled binary Bose-Einstein condensates, which has four parameters μ,δ,α and β, where μ denotes the strength of the spin-orbit coupling, δ is the detuning parameter,α and β are the parameters of the self-and cross-interaction, respectively. For the case β=α, by a direct ansatz, two kinds of stripe solitons, namely, the oscillating dark-dark solitons are obtained; meanwhile, a transformation is presented such that from the solutions of the integrable Manakov system, one can get soliton solutions for the spin-orbit coupled Gross-Pitaevskii equation. For the case β=3α, a bright-W type soliton for α>0 and a kink-antikink type soliton for α<0 are presented. It is found that the relation between μ and δ can affect the states of the solitons. Based on these solutions, the corresponding dynamics and the impact of the spin-orbit coupling effects on the quantum magnetization and spin-polarized domains are discussed. Our results show that spin-orbit coupling can result in rich kinds of soliton states in the two-component Bose gases, including the stripe solitons as well as the classical non-stripe solitons, and various kinds of multi-solitons. Furthermore, spin-orbit coupling has remarkable influence on the behaviors of quantum magnetization. In the experiments of Bose-Einstein condensates, there have been many different methods to observe the soliton states of the population distribution, the magnetic solitons, and the spin domains, so our results provide some possible options for the related experiments.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"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":"90188703","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}

{"title":"Design and fabrication of the superconducting single-photon detector operating at the 5 - 10 micrometer wavelength band","authors":"Chen Qi, Dai Yue, Li Fei-Yan, Zhang Biao, Li Hao-Chen, Tan Jing-Rou, Wang Xiao-Han, He Guang-Long, Fei Yue, Wang Hao, Zhang La-Bao, Kang Lin, Chen Jian, Wu Pei-heng","doi":"10.7498/aps.72.20221594","DOIUrl":"https://doi.org/10.7498/aps.72.20221594","url":null,"abstract":"High-performance mid-wave and long-wave infrared single-photon detectors not only have significant research value in the fields of infrared astronomy and defense technology, but are also challenging to be realized in the field of single-photon detection technology. Superconducting nanowire single-photon detectors (SNSPDs) have shown excellent performance in the near-infrared band. However, how to further improve the cutoff wavelength λc is a topic of widespread concern. In this paper, the method for improving λc by applying the regulation of the superconducting disorder is discussed, and a detector with an operating wavelength band of 5 - 10 μm is designed and fabricated. Studies have shown that the multiplication and diffusion behaviors of the quasiparticles always occur during the photon detection events, although the microscopic photodetection mechanism of SNSPD still lacks a perfect theoretical explanation. Therefore, the theoretical analysis mainly considers the influence of the quasiparticles in this paper, and the mathematical formula of the detection cutoff wavelength λc can be obtained based on the phenomenological quasiparticle diffusion model. Furthermore, the disorder-dependent superconducting phase transition temperature Tc, superconducting energy gap D, and electron thermalization time τth are also considered, in order to get more precise results.Theoretical analysis suggests that the increase in the sheet resistance Rs, which evaluates the disorder strength, will help to increase λc. For example, when the nanowire width is kept at 30 nm and Rs &gt; 380 Ω/□, it can be deduced that λc is larger than 10 μm.Experimentally, the active area of the device consists of a straight superconducting nanowire with a length of 10 μm and a width of 30 nm, so that it can effectively reduce the probability of the defects on the nanowire and avoid the current crowding effect. We have fabricated a 30 nm-wide Mo0.8Si0.2 mid infrared SNSPD, which has a cutoff wavelength λc no more than 5 μm, the effective strength of the disorder - the film sheet resistance Rs = 248.6 Ω/□. As a comparison, the sheet resistance, which is controlled by the film thickness, is increased to about 320 Ω/□ in this experiment.It is demonstrated that the Mo0.8Si0.2 detector with Rs ~320 Ω/□ can achieve saturated quantum efficiency at a wavelength of 6 μm. Furthermore, 53% quantum efficiency at the wavelength of 10.2 μm can be obtained when the detector works at a bias current of 0.9 ISW (ISW is the superconducting transition current), and it can theoretically reach a maximum value of 92% if the compression of switching current is excluded. Therefore, it can be predicted that the disorder regulation may become another efficient approach for designing high-performance mid-wave and long-wave infrared SNSPDs, in addition to the optimization of the superconducting energy gap and the cross section of superconducting nanowire.However, the continuous increase in the disorder will cause a d","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"85 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90589201","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}

{"title":"Deep Learning-Based Hole-Boring Radiation Pressure Ion Acceleration Modeling","authors":"Zhang Pu-Du, Wang Wei-Quan, Li Zhe-Min, Zhang Zi-Xuan, Wang Ye-Chen, Zhou Hong-Yu, Yin Yan","doi":"10.7498/aps.72.20230702","DOIUrl":"https://doi.org/10.7498/aps.72.20230702","url":null,"abstract":"Laser-driven ion acceleration has potential applications in high energy density matter, ion beam-driven fast ignition, beam target neutron source and warm dense matter heating and etc. Ultrashort relativistic lasers interacting with solid targets can generate ion beams with energies up to several hundreds of MeV, and the quality of the ion beams strongly depends on the interaction parameters of the laser and the targets. Developments in deep learning can provide new methods in the analysis of relationship between parameters in physics systems, which can significantly reduce the computational and experimental cost. In this paper, a continuous mapping model of ion peak and cutoff energies is developed based on a fully connected neural network(FCNN). In the model, the dataset is composed of nearly 400 sets of particle simulations of laser-driven solid targets, and the input parameters are laser intensity, target density, target thickness and ion mass. The model obtains the parameter analysis results in a large range of values with sparser parameter taking values, which greatly reduces the computational effort of sweeping the parameters in a large range of multi-dimensional parameters. Based on the results of this model mapping, the correction formula for the ion peak energy over ion mass is obtained. Furthermore, the ratio of ion cutoff energy and peak energy of each set of particle simulation is calculated. Repeating the same training process of ion peak energy and cutoff energy, the continuous mapping model of energy ratio is developed. According to the energy ratio model mapping results, the quantitative description of the relationship between ion cutoff energy and peak energy is realized, and the fitting formula for the cutoff energy of the Hole-Boring Radiation Pressure Acceleration (HB-RPA) mechanism is obtained, which can provide an important reference for the laser-driven ion acceleration experiments design.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"26 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90636821","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}

{"title":"Synthesis and luminescent properties of rare earths doped Gd2Te4O11 tellurite phosphors","authors":"Luo Jie, Zhang Zi-Qiu, Xu Jun-Hao, Qin Zhao-Ting, Zhao Yuan-Shuai, He Hong, Li Guan-Nan, Tang Jian-Feng","doi":"10.7498/aps.72.20221341","DOIUrl":"https://doi.org/10.7498/aps.72.20221341","url":null,"abstract":"A series of rare earth Dy³⁺, Tb³⁺, Eu³⁺ singly doped Gd₂Te₄O₁₁ (GTO) tellurite phosphors with intrinsic polarity were prepared by hydrothermal method. The phase structure, morphology and thermal stability of the phosphors were characterized. Their luminescence properties were tested in detail. The results show all those phosphors were crystalized into single phase of digadolinium tellurite with short rod-like shape. The maximum size achieved microns in axial direction. The phosphors have good thermal stability. For the GTO:Dy³⁺, the fluorescence emission under UV excitation is mainly located in the yellow-green region. The optimal doping concentration corresponding to the strongest excitation and emission is 2.5%, and the CIE color coordinates are (0.39, 0.43). The fluorescence decay curves show that the lifetime of the GTO:Dy³⁺ on ⁴F_9/2 energy level decreases gradually with increasing doping concentration of Dy³⁺, which may be related to the cross relaxation (CR) between Dy³⁺ ions. For the GTO:Eu³⁺, the fluorescence emission under UV excitation is mainly located in the red and orange-red regions. The emission intensity was enhanced with increasing doping concentration of Eu³⁺. When the doping concentration is 10%, the CIE color coordinates are (0.62, 0.38), which located in the orange-red region with high color purity. The fluorescence lifetime of Eu³⁺ on ⁵D₀ energy level is hardly affected by the change of Eu³⁺ doping concentration. For the GTO:Tb³⁺, with increasing the Tb³⁺ concentration, the fluorescence emission under UV excitation changes from blue-violet region to yellow-green region, which can be ascribed to the influence of CR between Tb³⁺ ions. The fluorescence decay behavior revealed that the Tb³⁺ ions on ⁵D₄ excited state may undergo energy transfer and reabsorption, which deviated fluorescence decay from the single exponential model. When the concentration of Tb³⁺ is 0.5%, the sample exhibits white light emission, having the CIE color coordinates of (0.33, 0.35) and color rendering index of 86. The measurements of temperature-dependent emission spectra show that the above-mentioned phosphors have good luminescent thermal stability. The internal quantum efficiencies (IQE) of those three types of phosphors were tested, and the IQE of GTO:Eu³⁺ are better than those of GTO:Dy³⁺ and GTO:Tb³⁺. All those phosphors still have much room for improvement in the luminescent performance. These phosphors have potential for the use of UV-excited white LED.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"10 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90822671","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}

{"title":"Phase separation in mixed systems of active particles with low and high inertia","authors":"Wang Jing Jiao Yang Tian Wen-De Chen Kang, 焦阳, 田文得, 陈康","doi":"10.7498/aps.72.20230792","DOIUrl":"https://doi.org/10.7498/aps.72.20230792","url":null,"abstract":"Active matter refers to a class of substances capable of autonomously moving by harnessing energy from their surrounding environment. These substances exhibit unique non-equilibrium phenomena, and hence have attracted great attention in the scientific community. Many active matters, such as bacteria, cells, micro-swimmers, and self-propelled colloidal particles, operate in viscous environment and their motions are usually described using overdamped models. Examples include overdamped active Brownian particle (ABP) model for self-propelled colloidal particles in solution and run-and-tumble (RTP) model for swimming bacteria. In recent years, increasing research studies have focused on the impact of inertia on the behavior of active matter. Vibrating robots, runners, flying insects, and micro-fliers are example active systems in the underdamped condition. The motion of these active matters can be modelled by underdamped Langevin equation, known as the active inertial particle (AIP) model. Previous studies have demonstrated that, similar to ABP systems, motility-induced phase separation (MIPS) phenomena also happen in AIP systems under certain density conditions. However, due to the strong collision-and-rebound effect, aggregation of AIP particles and hence the MIPS are impeded. In complex living/application environments, mixture of different active agents is often seen. Some studies on mixed systems of active matter show that the composition is an important quantity, influencing the phase separation phenomena. In this paper, we study the phase separation phenomena in mixed systems composed of low- and high-inertia active particles by underdamped Langevin dynamics simulations. We find that, compared to single-component system, the mixed systems are unexpectedly more favorable for the occurrence of phase separation at moderate overall concentration and certain range of component fraction, while more unfavorable for phase separation at high overall concentration. The underlying mechanism is that the presence of a small amount of the high-inertia particles could accelerate the motion of the low-inertia particles, and hence facilitate their aggregation and promote the phase separation. However, when the fraction of the high-inertia particles is large, frequent elastic collisions would disturb the aggregation of the low-inertia particles and suppress the occurrence of phase separation. Our results provide new sights into the collective behavior of active materials and also a reference for their design and applications.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"26 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86842477","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}

{"title":"Composite Basis Set of Plane Wave and Gaussian Function or Spline Function","authors":"Zhang Guang-Di, Mao Li, Xu Hong-Xing","doi":"10.7498/aps.72.20230872","DOIUrl":"https://doi.org/10.7498/aps.72.20230872","url":null,"abstract":"By combining plane waves with Gaussian or spline functions, this paper constructs a new composite basis set. As a non local basis vector, the plane wave basis group needs a large number of plane waves to expand all parts of the physical space, including the intermediate regions that are not important to our problems. Our basis set uses the local characteristics of Gaussian function or spline function at the same time, and controls the energy interval by selecting different plane wave vectors, so as to realize the partition solution of Hamiltonian matrix. Orthogonal normalization of composite basis sets is performed using Gram-Schmidt's orthogonalization method or Löwdin's orthogonalization method. Considering the completeness of plane wave vector, a certain value of positive and negative should be selected at the same time. Here, by changing the absolute value of wave vector, we can select the eigenvalue interval to be solved. The plane wave with a specific wave vector value is equivalent to a trial solution in the region with gentle potential energy. The algorithm automatically combines local Gaussian or spline functions to match the wave vector value difference between the trial solution and the strict solution. By selecting the absolute value of the wave vector in the plane wave function, this paper turns the calculation of large Hamiltonian matrices into the calculation of multiple small matrices, together with reducing the basis numbers in the region where the electron potential changes smoothly, we can significantly reduce the computational time. As an example, we apply this basis set to a one-dimensional finite depth potential well, it can be found that our method significantly reduce the number of basis vectors used to expand the wave function while maintaining a suitable degree of computational accuracy. We also studied the impact of different parameters on calculation accuracy. Finally, the above calculation method can be directly applied to the DFT calculation of plasmons in silver nanoplates or other metal nanostructures. Given a reasonable tentative initial state, the ground state electron density distribution of the system can be solved by self consistent solution using DFT theory, and then the electromagnetic field distribution and optical properties of the system can be solved using time-dependent density functional theory theory (TDDFT).","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86919790","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}

{"title":"Channel processing-based time-reversal method for multi-target tunable focusing","authors":"Chen Chuan-Sheng, Ding Shuai, Han Xu, Wang Bing-Zhong","doi":"10.7498/aps.72.20230547","DOIUrl":"https://doi.org/10.7498/aps.72.20230547","url":null,"abstract":"Achieving tunable focus of electromagnetic field energy at multiple target points is a critical challenge in the wireless power transfer (WPT) domain. Although techniques such as optimal constrained power focusing (OCPF) and time reversal (TR) have been proposed. The former presents limited practical applicability while the latter is noteworthy for its adaptive spatio-temporal synchronous focusing characteristics. However, the time reversal mirror (TRM) method necessitates intricate pretesting and has highly complex systems. In this study, we introduce a novel channel processing method, named channel extraction, selection, weighting, and reconstruction (CESWR), to attain balanced power distribution for multiple users, characterized by low complexity, high computability, and rapid convergence. Diverging from the traditional TR approach, our proposed method, grounded in channel correlation considerations, filters the channel impulse response (CIR) for multiple targets, segregating them into distinct characteristic and similar components for each target. This method ensures focused generation at both receiving ends while facilitating high-precision regulation of the peak voltage of the received signal. Furthermore, this study embarks on a rigorous examination of the linearity intrinsic to the proposed methodology, explicating a singular correspondence between the tuning of theoretical weights and the resultant outcomes. In order to authenticate the efficacy of this methodology, we construct a single-input multiple-output time-reversal cavity (SIMO-TRC) system for the experimental section of this manuscript. Subsequent experimentation, conducted for both loosely and tightly correlated models, furnishes invaluable insights. Evidently, in the loosely correlated model, the CESWR method exhibits proficiency in attaining a peak voltage ratio (PVR) of nearly 1.00 at the two receivers, with a minuscule numerical discrepancy of merely 8×10-6 mV. In stark contrast, under the tightly correlated model, the CESWR method demonstrates an enhanced ability to differentiate between two targets, thus offering a noticeable improvement over the classic single-target TR method.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"18 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91294217","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}

{"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}

{"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}