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25 May 2024, Volume 2024 Issue 3 Previous Issue    Next Issue

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Relativity and Gravitation Field

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Dirac and Majorana neutrino scattering by cosmic torsion in spatial-flat FRW spacetime background Wei LIN, Xun XUE 2024, 2024 (3):  1-11.  doi: 10.3969/j.issn.1000-5641.2024.03.001 Abstract ( 150 )   HTML ( 18 )   PDF (671KB) ( 152 )   Save The possibility of detecting cosmic torsion originated from large scale Lorentz violation of cosmology at cosmic scale by the shift of energy distribution for massive cosmic neutrinos in spatial-flat FRW (Friedmann-Robertson-Walker) spacetime background is discussed. Massive cosmic neutrino scattering owing to cosmic torsion leads to a shift in the peak position of their final state energy distribution at the order of $m^2/E^2$. Moreover, the Dirac and Majorana neutrino shift values differ by the vector part of the torsion in the non-minimal vector torsion coupling case. References | Related Articles | Metrics

Nuclear and High-Energy Physics

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Study of baryon magnetic moments in covariant chiral effective theory Haifeng ZHOU, Jifeng YANG 2024, 2024 (3):  12-26.  doi: 10.3969/j.issn.1000-5641.2024.03.002 Abstract ( 92 )   HTML ( 6 )   PDF (1586KB) ( 77 )   Save In this paper, we calculate the next-to-leading order (NLO) corrections to the baryon mass and magnetic moment using the covariant chiral perturbation theory within the extended minimal subtraction$({\text{E}}\overline {{\text{MS}}})$scheme under SU(3). We also present a comparative analysis of the experimental data and lattice quantum chromodynamics data with the $ {\text{E}}\overline {{\text{MS}}} $ results, and extrapolate it into physical value. We show that $ {\text{E}}\overline {{\text{MS}}} $ provides a reasonable theoretical and numerical result at the NLO, better than those obtained from the heavy-baryon approach and infrared regularization, and close to that obtained by the extended-on-mass-shell (EOMS) scheme. Figures and Tables | References | Related Articles | Metrics

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Research on the muon excess in ultrahigh-energy cosmic ray of extensive air-showers Zhiyi CUI, Jintao WU, Jianhong RUAN 2024, 2024 (3):  27-35.  doi: 10.3969/j.issn.1000-5641.2024.03.003 Abstract ( 116 )   HTML ( 4 )   PDF (948KB) ( 31 )   Save Recently, several air shower observatories established that the number of muons produced in ultrahigh-energy cosmic rays from extensive air-showers is significantly larger than that predicted by models. This study confirms that when ultrahigh-energy cosmic rays scatter on air particles, gluon condensation may occur. At this point, the production of strange quarks is significantly enhanced, such that more kaon will be generated in fragmentation products, and the air shower energy will be further distributed to the hadron cascade, which may explain the muon puzzle. Figures and Tables | References | Related Articles | Metrics

First-Principle Calculations

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Structural phase transitions of Th2N2S under high pressure: A first-principles calculation study Runrun DU, Shan WANG, Xuezhi KE 2024, 2024 (3):  36-44.  doi: 10.3969/j.issn.1000-5641.2024.03.004 Abstract ( 116 )   HTML ( 6 )   PDF (2190KB) ( 131 )   Save Based on the first-principles calculations and particle swarm optimization algorithm, the crystal structures and physical properties of Th2N2S are examined in the pressure range of 0~200 GPa. Our results successfully reproduce the experimental phase$P\bar {{3}}m1$ at ambient pressure and predicted two new structures at high pressure: the I4/mmm and Cmmm phases. A series of pressure-induced structural phase transitions were determined, namely from the$P\bar {{3}}m1$ phase to the I4/mmm phase, and then to the Cmmm phase, with corresponding phase transition pressures of 48.2 GPa and 156.2 GPa. The phonon dispersion curves and elastic constants of Th2N2S indicate that these three phases are dynamically and mechanically stable. The obtained mechanical properties demonstrate the natural ductility of the $P\bar {{3}}m1$, I4/mmm and Cmmm phases. Among them, the anisotropy degree of the Cmmm phase is the largest. Further, our electronic structure calculations show that the phase transition from the$P\bar {{3}}m1$ to I4/mmm is a semiconductor-metal phase transition. Figures and Tables | References | Related Articles | Metrics

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Research on calculation of two-dimensional transition metal chalcogenides compounds MX2-MX-MX2 (M = V, Cr, Mn, and Fe; X = S, Se, and Te) Wenjie DING, Wenhui XIE 2024, 2024 (3):  45-53.  doi: 10.3969/j.issn.1000-5641.2024.03.005 Abstract ( 236 )   HTML ( 6 )   PDF (1969KB) ( 186 )   Save The crystal structure, stability, electronic structure, and magnetism of two-dimensional transition metal chalcogenides compounds, MX2-MX-MX2 (M = V, Cr, Mn, and Fe; X = S, Se, and Te), were systematically investigated using first-principles calculations based on the density functional theory (DFT). Furthermore, the magnetic coupling mechanisms of these materials were analyzed. The results show that the formation energies of these compounds are negative, indicating that the compounds can be fabricated experimentally. MnS2-MnS-MnS2 and MnSe2-MnSe-MnSe2 exhibit ferromagnetic half-metal properties, whereas CrS2-CrS-CrS2 transforms into a ferromagnetic half-metal under applied stress. Figures and Tables | References | Related Articles | Metrics

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Research on atomistic simulation of the coexistence of multiple interfacial states at heterogeneous solid-liquid interface Jiaojiao LIU, Hongtao LIANG, Yang YANG 2024, 2024 (3):  54-63.  doi: 10.3969/j.issn.1000-5641.2024.03.006 Abstract ( 142 )   HTML ( 8 )   PDF (5107KB) ( 134 )   Save Engineering interfacial complexion (or phase) transitions has been a growing trend in grain boundary and solid surface systems. In addition, little attention has been paid to chemically heterogeneous solid-liquid interfaces. In this study, atomistic simulations are conducted to reveal the coexistence of novel in-plane multi-interfacial states in a Cu(111)/Pb(L) interface at a temperature just above the Pb freezing point. Four monolayer interfacial states, that is, two CuPb alloy liquids and two pre freezing Pb solids, are observed to coexist within two interfacial layers sandwiched between the bulk solid Cu and bulk liquid Pb. Computation of the spatial variations of various properties along the direction normal to the in-plane solid-liquid boundary lines for both interfacial layers presents a rich and varied picture of inhomogeneity and anisotropy in the mechanical, thermodynamical, and dynamical properties. The “bulk” values extracted from the in-plane profiles suggest that each interfacial state examined has distinct equilibrium values and significantly deviates from those of the bulk solid and liquid phases. It also indicates that the “complexion (or phase) diagrams” for the Cu(111)/Pb(L) interface bear a resemblance to those of the eutectic binary alloy systems as opposed to the monotectic phase diagram for the bulk CuPb alloy. The reported data supports the development of interfacial complexion (or phase) diagrams and interfacial phase rules and provides new guidelines for regulating heterogeneous nucleation and wetting processes. Figures and Tables | References | Related Articles | Metrics

Atomic，Molecular, and Optical Physics

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Bose-Einstein condensates in spin-twisted optical lattices Meiling WANG, Chengyi ZUO, Yan LI 2024, 2024 (3):  64-72.  doi: 10.3969/j.issn.1000-5641.2024.03.007 Abstract ( 155 )   HTML ( 6 )   PDF (1854KB) ( 205 )   Save The characteristics of the ground states of Bose-Einstein condensates (BEC) in spin-dependent bilayer square optical lattices are investigated in this paper. The relative twist angle between the two lattices and the interlayer coupling strength are the main tunable parameters that affect the density distribution of the ultracold atoms. When the lowest band of the lattices exhibits a single-well dispersion, the localization of the ultracold atoms in the Moiré lattice can be determined from the twist angle, interlayer coupling strength, number of atoms, and lattice depth. When the lowest band of the lattices exhibits a double-well dispersion, the twist between the lattices leads to the twist of the two spin states. With an increase in interlayer coupling strength, the two twisted spin states will overlap. The results of this work will stimulate further exploration of novel quantum effect with ultracold atoms in twisted optical lattices. Figures and Tables | References | Related Articles | Metrics

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Floquet two-body problem in a harmonic trap Dongfan YAN 2024, 2024 (3):  73-83.  doi: 10.3969/j.issn.1000-5641.2024.03.008 Abstract ( 149 )   HTML ( 5 )   PDF (1251KB) ( 129 )   Save The dynamics of quantum gases with time-varying interactions have attracted research interests owing to recent advances in experimental techniques such as optical Feshbach resonance. A range of novel dynamic behaviors including the Farady pattern and Bose fireworks have been observed in these systems. In this research, the dynamic problem of two harmonically trapped atoms with periodically modulating interaction strength is investigated. Because of the Hamiltonian time dependence, the system energy is an unconserved quantity. However, we may continue to utilize the Floquet theory for the time-periodic Hamiltonian and define its quasi-energy. The exact equations for the quasi-energies of the two-body problem are derived. Upon numerically solving these equations, we identify that the two-body quasi-energy spectrum exhibits various novel behaviors for different driven parameters or frequencies. Figures and Tables | References | Related Articles | Metrics

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An efficient algorithm for solving time-dependent Gross-Pitaevskii equation Lisha SHU, Guangjiong DONG 2024, 2024 (3):  84-90.  doi: 10.3969/j.issn.1000-5641.2024.03.009 Abstract ( 192 )   HTML ( 7 )   PDF (747KB) ( 313 )   Save The Gross-Pitaevskii equation is widely applied in Bose-Einstein condensate research, yet is rarely analytically determined; thus, it is important to develop a numerical method with high precision to resolve this. Accordingly, a numerical method was developed in this work, considering the splitting step method, Crank-Nicolson algorithm, and Numerov algorithm with four-order accuracy. The corresponding test shows that compared with the finite difference method using five points, the proposed algorithm is more efficient and costs less memory. Figures and Tables | References | Related Articles | Metrics

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Research on the overestimation of sensitivity in lossy SU(2) and SU(1,1) interferometers Jie ZENG, Chunhua YUAN 2024, 2024 (3):  91-100.  doi: 10.3969/j.issn.1000-5641.2024.03.010 Abstract ( 105 )   HTML ( 3 )   PDF (1258KB) ( 38 )   Save In this study, based on the lossy SU(2) and SU(1,1) interferometer models, phase estimation in interferometers was investigated. The general expression for the overestimated quantum Fisher information (QFI), which exists when performing single-parameter phase estimation compared to two-parameter phase estimation, was theoretically studied. In addition, the variation in the overestimated QFI with the loss factor or beam splitting ratio was numerically analyzed with the input of coherent and squeezed vacuum states, and the disappearance and recovery of the overestimated QFI was related to the beam splitting ratio, gain factor, and squeeze amplitude. By adjusting the beam splitting ratio and loss factor, the best sensitivity was obtained, which is beneficial for quantum precision measurements in lossy environments. Figures and Tables | References | Related Articles | Metrics

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Theoretical study of laser parameter-dependent properties of high-order harmonic generation in solids based on different physical mechanisms Xiance XIE, Zijian HU, Zhihong YANG, Yunhui WANG, Shicheng JIANG 2024, 2024 (3):  101-112.  doi: 10.3969/j.issn.1000-5641.2024.03.011 Abstract ( 159 )   HTML ( 3 )   PDF (4427KB) ( 139 )   Save In the study of high-order harmonic generation mechanisms, the main focus has been on interband polarization and intraband currents, as well as anomalous current mechanisms caused by Berry curvature. The long-neglected mixture term currents have been obtained by decomposing the strong laser-induced intact currents into contributions from different mechanisms. In this study, the peak amplitude and laser wavelength dependence of the high harmonics generated by different mechanisms were investigated by numerically solving the semiconductor Bloch equations (SBE). The interference between the current mechanisms was explored. It was found that the high-order harmonic spectra induced by the mixture term currents and the interband polarization currents have extremely similar variation patterns and extremely close harmonic intensities, both with the change in wavelength and the change in peak amplitude. Additionally, the anomalous harmonics were found to produce only even harmonics perpendicular to the polarization direction of the laser field. The anomalous harmonics are unique in that they have a minimum during wavelength and peak intensity variations. Analyzing the interference effects between the different mechanisms revealed that the interband polarization harmonics and intraband harmonics (including anomalous harmonics) interfere significantly with each other in the vertical polarization direction, while the interference of mixture term harmonics with intraband harmonics is negligible. Figures and Tables | References | Related Articles | Metrics

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Research on optimization of the coupling efficiency of near-infrared lithium niobate grating coupler Siqi LIU, Minni QU, Wei XIE 2024, 2024 (3):  113-120.  doi: 10.3969/j.issn.1000-5641.2024.03.012 Abstract ( 157 )   HTML ( 7 )   PDF (2397KB) ( 124 )   Save We propose an efficient grating coupler design scheme based on a lithium niobate guided mode structure and its optimized optical excitation configuration. The coupling effect of the grating coupler is numerically analysed using the finite time domain difference algorithm. We study the effects of the grating period, grating duty ratio, silica isolation layer thickness, polarization and angle of incident light on the coupling efficiency of the grating. The spatial light propagation electric field images are simulated for resonant and non-resonant wavelengths. The results show that with a grating period of 650 nm, a grating duty cycle of 0.3 and an etching depth of 130 nm, an optimised grating coupling efficiency of ~38% can be obtained using TM(transverse magnetic) polarised light incident along the grating normal angle of 17°, thus effectively coupling spatial light into the lithium niobate subwavelength waveguide film. This is of great reference value for the design and application performance of LiNbO3 micro-nano grating couplers. Figures and Tables | References | Related Articles | Metrics

Quantum Physics and Quantum Information Processing

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An algorithm for keeping unitary evolution of a wave function in time-dependent potential field Jiaying SONG, Guangjiong DONG 2024, 2024 (3):  121-127.  doi: 10.3969/j.issn.1000-5641.2024.03.013 Abstract ( 84 )   HTML ( 2 )   PDF (1012KB) ( 23 )   Save The numerical solution for wave function evolution plays an important role in quantum mechanics research. Many numerical algorithms have been developed for time-independent potential fields. However, multiple physical problems exist with the time-dependent potential. In this case, previously developed algorithms cannot guarantee the unitary evolution of wave function. In this study, the Crank-Nicolson algorithm to maintain unitary evolution in time-dependent potential fields is developed with a fourth-order accurate Numerov algorithm used to achieve high-precision spatial discretization. A numerical test demonstrates that the new algorithm maintains the unitarity and stability of wavefunction evolution. Figures and Tables | References | Related Articles | Metrics

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Quantum parameter estimation and initial state optimization based on the Jaynes-Cummings model Liwen QIAO, Jiaxin PENG, Baiqiang ZHU, Keye ZHANG 2024, 2024 (3):  128-135.  doi: 10.3969/j.issn.1000-5641.2024.03.014 Abstract ( 139 )   HTML ( 2 )   PDF (903KB) ( 75 )   Save Quantum parameter estimation is a powerful theoretical tool for inferring unknown parameters in physical models from experimental data. The Jaynes-Cummings model is widely used in quantum optics, and describes the interaction between a two-level atom and a single-mode quantum optical field. Systematic research was performed on the estimation precision of atom-light coupling strength “g” in this model and the initial state was identified by which the estimation can achieve the best precision. Our results can improve the precision of quantum measurement with the Jaynes-Cummings model, and can be used for quantum metrology with other hybrid quantum systems. Figures and Tables | References | Related Articles | Metrics

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E-payment protocol scheme based on quantum entanglement measurement theory Minhao ZHU, Lei MA 2024, 2024 (3):  136-146.  doi: 10.3969/j.issn.1000-5641.2024.03.015 Abstract ( 82 )   HTML ( 3 )   PDF (761KB) ( 37 )   Save An electronic payment protocol based on basic quantum mechanics is proposed. Some current loopholes in the classic payment systems pose security risks. The proposed scheme utilizes the correlations existing between entangled particles at the quantum level to implement the steps of signing, purchasing, and paying, whereby the validity of a signature is verified via quantum one-way functions and quantum SWAP test circuits. Payment information is transmitted through redundant particles in channel detection, thereby saving costs. Experimental results show that the proposed scheme has unconditional security as guaranteed by the basic principles of quantum mechanics and meets the basic requirements of payment systems. Figures and Tables | References | Related Articles | Metrics

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Linear entropy uncertainty relation of Ising model under Dzyaloshinskii-Moriya interaction Yu ZHAO, Jinming LIU 2024, 2024 (3):  147-155.  doi: 10.3969/j.issn.1000-5641.2024.03.016 Abstract ( 81 )   HTML ( 2 )   PDF (945KB) ( 19 )   Save In this research, by considering the two-qubit Ising model under Dzyaloshinskii-Moriya(DM) interaction as the research object, we investigate the effects of coupling strength, DM interaction and ambient temperature on the linear entropy uncertainty relation(EUR) in the system. Meanwhile, the variation of thermal entanglement with environment with ambient temperature is also discussed, and the relationship between thermal entanglement and linear EUR is compared. The results demonstrate that the systemic linear entropy uncertainty and thermal entanglement variance trend depends on the selection of environmental parameters, and their overall evolution behavior is roughly anti-related. Additionally, for a complete set of mutually unbiased bases, when different measurement base combinations are selected, the uncertainty relation lower bound will vary with the change in the number of measurement bases; moreover, the linear EUR can be transformed into an equation in special cases and its lower bound does not depend on the selection of a specific observation quantity. Compared with the previous quantum memory-assisted EUR, it provides a useful reference for precise measurement. Figures and Tables | References | Related Articles | Metrics

Complex Network Dynamics

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The impact of relative time scale on the coupling propagation dynamics of information diffusion and opinion formation Yiwen LIU, Ming TANG 2024, 2024 (3):  156-170.  doi: 10.3969/j.issn.1000-5641.2024.03.017 Abstract ( 93 )   HTML ( 9 )   PDF (3139KB) ( 28 )   Save In general, the evolutionary time scale of group opinion formation can be considered significantly larger than the message propagation time scale on social media. However, this assumption does not hold for some extreme scenarios. Based on this, we established a noise threshold voter-UAU (unaware-aware-unaware) coupled model with an adjustable relative time scale between message propagation and opinion formation, and studied the collaborative interaction between two dynamics under different relative evolutionary rates and its effects on each other’s dynamical evolution . Both analyses based on mean field theory and Monte Carlo simulations demonstrate that a smaller time scale for message propagation relative to opinion formation is more favorable for the formation of a bistable phase, which is caused by the inherent differences between the two dynamics and their synergistic interaction. This study identified that the relative time scale between both dynamics not only affects the proportion of “positive” opinions in the final state, but also the critical basic reproduction number for message propagation that leads to a phase transition in the model. In particular, when the proportion of “positive” opinion is at different levels, their behaviors with respect to changes in the relative time scale between the two dynamics differ. When the proportion of “positive” opinions is high, a smaller time scale for message propagation leads to a higher proportion of “positive” opinions, and vice versa. This study addresses a gap in this field regarding the relative time scale’s impact on the dynamics of collaborative interaction coupling. Furthermore, it facilitates a more in-depth understanding of the profound influence of the relative time scale on the evolution dynamics of coupling dynamics. Figures and Tables | References | Related Articles | Metrics