Physics Letters A最新文献

{"title":"Influence of the channel width on hall thruster instabilities by 2D radial-azimuthal particle-in-cell simulations","authors":"Xin Luo ,&nbsp;Zhijun Zhou ,&nbsp;Lihuan Xie ,&nbsp;Yixiang Peng ,&nbsp;Fengkui Zhang ,&nbsp;Yinjian Zhao","doi":"10.1016/j.physleta.2026.131366","DOIUrl":"10.1016/j.physleta.2026.131366","url":null,"abstract":"<div><div>The discharge channel width is a critical design parameter for Hall effect thrusters, yet its influence on the cross-field electron transport governed by plasma instabilities remains inadequately understood, especially when wall absorption is included. The influence of the discharge channel width is investigated using 2D radial-azimuthal particle-in-cell (PIC) simulations with absorbing wall boundaries and an analytic ionization model. The channel width <span><math><msub><mi>L</mi><mtext>r</mtext></msub></math></span> is varied from 3.2 mm to 25.6 mm. We find a non-monotonic dependence of linear instability growth rate on <span><math><msub><mi>L</mi><mtext>r</mtext></msub></math></span>. The ECDI-1st linear growth rate increases, then decreases (notably at <span><math><mrow><msub><mi>L</mi><mtext>r</mtext></msub><mo>=</mo><mn>12.8</mn></mrow></math></span> and 19.2 mm), and rises again at 25.6 mm. The MTSI exhibits a similar <span><math><msub><mi>L</mi><mtext>r</mtext></msub></math></span>-dependence with a pronounced reduction at <span><math><mrow><msub><mi>L</mi><mtext>r</mtext></msub><mo>=</mo><mn>19.2</mn><mspace></mspace><mtext>mm</mtext></mrow></math></span>. Wider channels enhance nonlinear activity, inducing spectrum broadening and a transition from discrete ECDI-dominated oscillations to a broadband state where MTSI becomes dominant. Consequently, the radial electron temperature <span><math><mrow><msub><mi>T</mi><mtext>e</mtext></msub><mspace></mspace><mtext>r</mtext></mrow></math></span> increases from  ∼ 10 eV (<span><math><mrow><msub><mi>L</mi><mtext>r</mtext></msub><mo>=</mo><mn>3.2</mn><mspace></mspace><mtext>mm</mtext></mrow></math></span>) to  ∼ 47 eV (<span><math><mrow><msub><mi>L</mi><mtext>r</mtext></msub><mo>=</mo><mn>25.6</mn><mspace></mspace><mtext>mm</mtext></mrow></math></span>), reversing the temperature anisotropy (from <em>T_eθ</em> &gt; <em>T</em>_er in narrow channels to <em>T_eθ</em> &lt; <em>T</em>_er in wide channels). The time-averaged electron mobility in the plasma bulk is suppressed as <span><math><msub><mi>L</mi><mtext>r</mtext></msub></math></span> increases (reduction  &gt; 25% in the present parameter set). These results suggest that, with the plasma source fixed, the increase of <span><math><msub><mi>L</mi><mtext>r</mtext></msub></math></span> due to the wall-induced particle losses and enhanced nonlinear coupling substantially modifies instability development and anomalous transport.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"573 ","pages":"Article 131366"},"PeriodicalIF":2.6,"publicationDate":"2026-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Realization of high-figure-of-merit sensing on tetrameric all-dielectric metasurfaces: Excitation of quasi-BIC through symmetry breaking","authors":"Ying Chen,&nbsp;Zhongyao Wang,&nbsp;Haoliang Zhou,&nbsp;Zhe Han,&nbsp;Xin Luo,&nbsp;Liyong Niu,&nbsp;Dandan Zhu","doi":"10.1016/j.physleta.2026.131378","DOIUrl":"10.1016/j.physleta.2026.131378","url":null,"abstract":"<div><div>High figure of merit (FoM) sensing relies on the field localization effects created by metasurface designs. The Bound State in the Continuum (BIC) must be broken into a quasi-BIC to leverage its ability to enhance light-matter interaction. This paper proposes a tetramer-based all-dielectric metasurface operating in the near-infrared band, which achieves the transition from a BIC to a quasi-BIC mode by breaking specific structural symmetries. We employ multipolar decomposition theory to reveal the nature of its resonance mode. Through numerical calculations, we analyze in detail the coupling relationship between the discrete eigenmode and the external continuum during the symmetry-breaking process. Furthermore, the optical properties of the excited high-<em>Q</em> quasi-BIC are analyzed using the time-domain coupled-mode theory. Structural parameters are optimized to obtain superior sensing characteristics. The metasurface structure proposed herein can be utilized for designing high-FoM sensors and holds significant application prospects in fields such as biomedical health monitoring.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"573 ","pages":"Article 131378"},"PeriodicalIF":2.6,"publicationDate":"2026-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Optimization of Pauli operations for numerical analysis of quantum state’s relative phase in spin-1/2 quantum system","authors":"Jin-Fang Li ,&nbsp;Yilou Liu ,&nbsp;Dong-Shan He ,&nbsp;Zuo-Yuan Zhang ,&nbsp;Xiao-Tao Xie","doi":"10.1016/j.physleta.2026.131371","DOIUrl":"10.1016/j.physleta.2026.131371","url":null,"abstract":"<div><div>Quantum optimal control is essential for realizing quantum computing, and the task is constructing high-fidelity quantum logic gates. Among the fundamental operations for qubit manipulation, Pauli gates play a pivotal role. In this study, we employ a multi-constrained quantum control method to investigate the phase modulation in spin-1/2 system for Pauli gates. Our results demonstrate that Pauli gates achieve target state preparation with fidelities above 0.9999 for selected initial states, where final population closely match theoretical predictions. Furthermore, we analyze phase control in specific quantum states. Theoretically, the Pauli-X gate induces a phase sign inversion, whereas Pauli-Y and Pauli-Z gates produce relative phases. Our optimized results show phase deviations within 0.0164<em>π</em> of theoretical values. Moreover, high fidelity can be maintained even when population is effected by initial phases. These phase evolution characteristics provide valuable guidance for optimizing quantum operations and improving computational accuracy.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"573 ","pages":"Article 131371"},"PeriodicalIF":2.6,"publicationDate":"2026-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Dynamics informed nonlinear vibration analysis with adaptive location point framework for fish tail tapered beam","authors":"Jing-Yan Niu","doi":"10.1016/j.physleta.2026.131340","DOIUrl":"10.1016/j.physleta.2026.131340","url":null,"abstract":"<div><div>This study is inspired by the efficient oscillation mechanism of fish tails and investigates the nonlinear frequency-amplitude relationship of tapered beams. A dimensionless nonlinear differential equation governing large-amplitude vibrations is derived, incorporating geometric nonlinearities inherent to variable cross-sections. The limitations of traditional analytical methods in handling strong nonlinearities are first clarified. To address this fundamental challenge, two novel analytical approaches are proposed. One is an adaptive location point framework based on He's frequency-amplitude formulation, which dynamically optimizes the linearized position to improve accuracy under strong nonlinearity. The second is He's transform-based variational iteration method, which transforms the problem into a functional form that is easy to iteratively solve. Both methods converge to a unified, closed-form expression for the nonlinear frequency. Validation against exact solutions and numerical simulations demonstrates high accuracy and computational efficiency. Specifically, for an amplitude reaching 30% of the beam length, the frequency prediction error of the adaptive positioning point method is still less than 2%. The He’s transform-based variational iteration method significantly reduces the number of iterations required for convergence compared to traditional methods under the same nonlinear intensity. Further analysis reveals that the taper parameter critically influences the system's nonlinear characteristics. These methods provide a robust and efficient tool for the rapid design analysis of bio-inspired structures, such as robotic swimmers and lightweight aerospace components.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131340"},"PeriodicalIF":2.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Local group velocity distribution inside superradiant condensates","authors":"Yin-Da Guo ,&nbsp;Kai-Dong Zhou ,&nbsp;Shou-Shan Bao ,&nbsp;Hong Zhang","doi":"10.1016/j.physleta.2025.131316","DOIUrl":"10.1016/j.physleta.2025.131316","url":null,"abstract":"<div><div>Superradiance enables scalar fields to extract energy and angular momentum from a rotating black hole (BH), leading to the formation of a BH-condensate system. Previous studies mainly focus on the phase velocity, which propagates in the azimuthal direction. In this work, we show that the superradiant scalar condensate presents a nontrivial group velocity distribution. In the region sufficiently far from the BH, the condensate exhibits a radial velocity magnitude that approaches <span><math><mrow><mrow><mo>(</mo><msub><mi>r</mi><mi>g</mi></msub><mi>μ</mi><mo>/</mo><mn>2</mn><mo>)</mo></mrow><mi>sin</mi><mrow><mo>(</mo><mn>2</mn><mi>ω</mi><mi>t</mi><mo>−</mo><mn>2</mn><mi>φ</mi><mo>)</mo></mrow></mrow></math></span>, while the polar and azimuthal velocity magnitudes asymptotically decline as ∝1/<em>r</em>.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131316"},"PeriodicalIF":2.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145904020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The universal violation of the Leggett-Garg macro-realism inequalities by all dynamical systems","authors":"C.S. Unnikrishnan","doi":"10.1016/j.physleta.2026.131346","DOIUrl":"10.1016/j.physleta.2026.131346","url":null,"abstract":"<div><div>The Leggett-Garg inequalities involving multi-time correlation functions are widely considered as the touchstone for what is defined as Macro-Realism of the physical world, which constitutes two main criteria: a) a macro-real system is in one of the possible definite discrete physical states at any given time, and b) measurements do not alter a physical state. There are continuing experimental investigations supposedly testing for macro-realism, reflected in the Leggett-Garg inequalities. I prove the surprising universal result that the Leggett-Garg inequalities are violated <em>by all dynamical physical systems that respect fundamental conservation laws</em>, and not merely by microscopic and macroscopic quantum systems. Hence, the inequalities are guaranteed to be violated by any realisable dynamical physical system, irrespective of the covering theory. The Leggett-Garg inequalities have no discriminatory role in the real world where ensemble-averaged correlation functions bridge the information content and the probabilities of microscopic quantum mechanics with the conservation constraints of the macroscopic world. The close connection to the violation of Bell’s inequalities is briefly discussed.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131346"},"PeriodicalIF":2.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Canonical pairs in finite-dimensional Hilbert space","authors":"Ralph Adrian E. Farrales,&nbsp;Eric A. Galapon","doi":"10.1016/j.physleta.2026.131344","DOIUrl":"10.1016/j.physleta.2026.131344","url":null,"abstract":"<div><div>A pair of Hermitian operators <span><math><mrow><mo>(</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo>)</mo></mrow></math></span> is canonical if they satisfy the commutator relation <span><math><mrow><mo>[</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo>]</mo><mo>=</mo><mi>i</mi><mi>ℏ</mi><mi>I</mi></mrow></math></span>, where <span><math><mi>I</mi></math></span> is the identity operator. However, the relation holds only in a proper subspace of the Hilbert space, referred to as the canonical domain. In infinite-dimensional Hilbert space, it was previously shown that canonical pairs exist in a canonical domain that is not necessarily dense. In finite-dimensional Hilbert space, we show in this work that canonical pairs exist in a closed proper subspace of the Hilbert space. We study the many possible canonical pairs and look into the uncertainty relation they satisfy. We apply our results by constructing time operators in finite-dimensional quantum mechanics. We show that the canonical domain determines the states in which measurement of these time operators yield parametric time.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131344"},"PeriodicalIF":2.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Regulation of strain and twist on electronic properties of VSe2/WSe2 van der Waals heterostructure","authors":"Ziyang Zhu ,&nbsp;Dan Jin ,&nbsp;Rui Xiong","doi":"10.1016/j.physleta.2025.131322","DOIUrl":"10.1016/j.physleta.2025.131322","url":null,"abstract":"<div><div>Using first-principles calculations, this study investigates the stability and electronic properties of VSe₂ and WSe₂ monolayers, as well as VSe₂/WSe₂ heterostructures. VSe₂ and WSe₂ monolayers are characterized as ferromagnetic and non-magnetic semiconductor, respectively. The dynamic and thermodynamic stability of VSe₂/WSe₂ heterostructure is confirmed through phonon spectra and molecular dynamics simulations. Energy comparisons across different magnetic states - including nonmagnetic, ferromagnetic, and antiferromagnetic - reveal that the heterostructure possesses a ferromagnetic ground state. Furthermore, based on the band structure and work function of the VSe₂/WSe₂ heterostructure, we found that the VSe₂/WSe₂ heterostructure exhibits type-II band alignment. Under the biaxial tensile strains (1-5%), the system transforms into half-metallic state, achieving 100% spin polarization at the Fermi level. Additionally, we find that the effect of twist angle on the electronic property of VSe₂/WSe₂ heterostructure can be ignored. Our research is of great significance for the development of the fields of optoelectronics and spintronics.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131322"},"PeriodicalIF":2.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"On fully entangled fraction of arbitrary d⊗d quantum states","authors":"Xue-Na Zhu ,&nbsp;Gui Bao ,&nbsp;Ming Li ,&nbsp;Ming-Jing Zhao ,&nbsp;Shao-Ming Fei","doi":"10.1016/j.physleta.2026.131324","DOIUrl":"10.1016/j.physleta.2026.131324","url":null,"abstract":"<div><div>We study the fully entangled fraction of quantum states based on the Bloch representation of density matrices. Analytical upper bounds on the fully entangled fraction are obtained for arbitrary <em>d</em>⊗<em>d</em> bipartite systems. The fully entangled fractions for classes of <em>d</em>⊗<em>d</em> quantum states are analytically derived. Detailed examples are given to illustrate the advantages of our results.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131324"},"PeriodicalIF":2.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Quantized resonant tunneling effect in Josephson junctions with ferromagnetic bilayers","authors":"Hao Meng ,&nbsp;Lei Cai ,&nbsp;Xianghe Zhao ,&nbsp;Xiuqiang Wu ,&nbsp;Jia Xu ,&nbsp;Guanqi Wang","doi":"10.1016/j.physleta.2025.131317","DOIUrl":"10.1016/j.physleta.2025.131317","url":null,"abstract":"<div><div>We study the Josephson effect in one-dimensional SF₁F₂S junctions, which consist of conventional s-wave superconductors (S) connected by two ferromagnetic layers (F₁ and F₂). At low temperatures, the potential barrier at the F₁/F₂ interface can induce a quantized resonant tunneling effect. This effect not only modifies the amplitude of the critical current but also affects the phase of the Josephson current. As the exchange fields (<em>h</em>₁, <em>h</em>₂) and thicknesses (<em>d</em>₁, <em>d</em>₂) of the F₁ and F₂ layers vary, the critical current displays periodic resonance peaks. These peaks occur under the quantization conditions <span><math><mrow><msub><mi>Q</mi><mrow><mn>1</mn><mo>(</mo><mn>2</mn><mo>)</mo></mrow></msub><msub><mi>d</mi><mrow><mn>1</mn><mo>(</mo><mn>2</mn><mo>)</mo></mrow></msub><mo>=</mo><mrow><mo>(</mo><msub><mi>n</mi><mrow><mn>1</mn><mo>(</mo><mn>2</mn><mo>)</mo></mrow></msub><mo>+</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>)</mo></mrow><mi>π</mi></mrow></math></span>, where <span><math><mrow><msub><mi>Q</mi><mrow><mn>1</mn><mo>(</mo><mn>2</mn><mo>)</mo></mrow></msub><mo>=</mo><mn>2</mn><msub><mi>h</mi><mrow><mn>1</mn><mo>(</mo><mn>2</mn><mo>)</mo></mrow></msub><mo>/</mo><mrow><mo>(</mo><mi>ℏ</mi><msub><mi>v</mi><mi>F</mi></msub><mo>)</mo></mrow></mrow></math></span> is the center-of-mass momentum carried by Cooper pairs, with <em>v_F</em> being the Fermi velocity, and <span><math><mrow><msub><mi>n</mi><mrow><mn>1</mn><mo>(</mo><mn>2</mn><mo>)</mo></mrow></msub><mo>=</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>⋯</mo></mrow></math></span>. It can be inferred that the potential barrier suppresses the transport of spin-singlet pairs while allowing spin-triplet pairs with zero spin projection along the magnetization axis to pass through. As these spin-triplet pairs traverse the F₁ and F₂ layers, the total phase they acquire determines the ground state of the Josephson junction. At the resonance peaks, the Josephson current primarily arises from the first harmonic in both the parallel and antiparallel magnetization configurations. However, in perpendicular configurations, the second harmonic becomes more significant. In scenarios where both ferromagnetic layers have identical exchange fields and thicknesses, the potential barrier selectively suppresses the current in the 0-state while allowing it to persist in the <em>π</em>-state for parallel configurations. Conversely, in antiparallel configurations, the current in the 0-state is consistently preserved.</div></div>","PeriodicalId":20172,"journal":{"name":"Physics Letters A","volume":"572 ","pages":"Article 131317"},"PeriodicalIF":2.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145904018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}