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Multi-polarized four-mode wideband vortex electromagnetic beams generation through reflective metasurface in Ka-band 通过 Ka 波段反射元面产生多极化四模宽带涡旋电磁波束
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-18 DOI: 10.1088/1402-4896/ad7649
Lu Tian, Rui Zhang, Yong Wang, Bingchuan Xie, Haixuan Li and Yueyan Ren
Orbital angular momentum (OAM) is a new dimension for improving channel capacity and has been widely studied by scientists. In recent years, there has been an increasing amount of research on antennas and electromagnetic (EM) beams containing OAM, demonstrating its excellent ability in communication. This article proposes a Ka-band multi-mode orbital angular momentum reflectarray antenna (RA) capable of generating four vortex EM beams with four modes (l = −1, 0, +1, +2). The proposed unit cell can cover a 360-degree reflection phase range with a magnitude above 0.88, achieved through a combination of variable-sized and delay-line units. Furthermore, the unit cell’s mirror configuration allows for cross-polarization rejection. Based on these unit cells, a square reflectarray antenna (25 × 25 elements) is designed, fabricated, and measured. The measured results demonstrate that the 1 dB bandwidths for four modes are 25.81% (27–35 GHz, l = −1), 31.25% (27–37 GHz, l = 0), 28.57% (27–36 GHz, l = +1), and 20.69% (26–32 GHz, l = +2), respectively. Notably, the 3 dB gain bandwidths of all modes exceed 40%, with the maximum 3 dB bandwidth reaching 47.62% at mode l = +1. Furthermore, all vortex EM beams of this proposed RA maintain mode purities exceeding 70% within 3 dB bandwidths.
轨道角动量(OAM)是提高信道容量的一个新维度,已被科学家广泛研究。近年来,对含有轨道角动量的天线和电磁(EM)波束的研究日益增多,显示了其在通信中的卓越能力。本文提出了一种 Ka 波段多模轨道角动量反射阵列天线(RA),能够产生四种模式(l = -1、0、+1、+2)的涡旋电磁波束。通过可变尺寸单元和延迟线单元的组合,拟议的单元可覆盖 360 度的反射相位范围,幅度超过 0.88。此外,该单元的镜面配置还可实现跨偏振抑制。基于这些单元,设计、制造并测量了一个方形反射阵列天线(25 × 25 个元件)。测量结果表明,四种模式的 1 dB 带宽分别为 25.81% (27-35 GHz, l = -1), 31.25% (27-37 GHz, l = 0), 28.57% (27-36 GHz, l = +1) 和 20.69% (26-32 GHz, l = +2)。值得注意的是,所有模式的 3 dB 增益带宽都超过了 40%,模式 l = +1 时的最大 3 dB 带宽达到了 47.62%。此外,该拟议 RA 的所有涡旋电磁波束都能在 3 dB 带宽内保持超过 70% 的模式纯度。
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引用次数: 0
Polarization-dependent near-field coupling and far-field harmonic modulation in a graphene-based plasmonic nanostructure 石墨烯基等离子纳米结构中的偏振相关近场耦合和远场谐波调制
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad78ca
Ye Ming Qing, Zhaoyan Yang, Yunxia Wang, Yongze Ren and Jun Wu
The interplay between light and matter has fostered innovative research in surface plasmons, specifically in graphene, due to its tunable Fermi energy and reduced losses in the infrared and terahertz spectra. This study explores the anisotropic coupling of nonlocalized surface plasmons in graphene with localized magnetic polaritons (MP) in a silicon carbide (SiC) array. By adjusting graphene’s Fermi energy and polarization angle, we successfully achieved hybrid coupling, giving rise to three clearly distinguishable hybridized states. Using the coupled oscillator model as a framework, we conducted an analysis of the intricate multimode coupling and accurately ascertained the weighting efficiencies of the individual modes comprising the hybrids. By integrating the design principles of space-time coding metasurfaces, we successfully broadened the scope of the application, extending its reach from the near-field to the far-field. These novel discoveries pave new paths for advancements in thermal emitters, photonic systems, energy conversion technologies, and the creation of cutting-edge plasmonic devices.
光与物质之间的相互作用促进了对表面质子的创新研究,特别是石墨烯,因为石墨烯具有可调费米能并能减少红外和太赫兹光谱中的损耗。本研究探讨了石墨烯中的非局域表面质子与碳化硅(SiC)阵列中的局域磁极子(MP)的各向异性耦合。通过调整石墨烯的费米能和极化角,我们成功地实现了混合耦合,产生了三种明显不同的混合态。我们以耦合振荡器模型为框架,对错综复杂的多模耦合进行了分析,并准确地确定了构成混合态的各个模式的加权效率。通过整合时空编码元表面的设计原理,我们成功地拓宽了应用范围,将其覆盖范围从近场扩展到远场。这些新发现为热发射器、光子系统、能量转换技术以及尖端等离子体设备的开发铺平了新的道路。
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引用次数: 0
A Mathematical Aspect of Bloch’s Theorem 布洛赫定理的数学方面
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad7767
Yan Li, Bin Yang and Aihui Zhou
In this paper, by studying a class of 1-D Sturm-Liouville problems with periodic coefficients, we show and classify the solutions of periodic Schrödinger equations in a multidimensional case, which tells that not all the solutions are Bloch solutions. In addition, we also provide several properties of the solutions and quasimomenta and illustrate the relationship between bounded solutions and Bloch solutions.
本文通过研究一类具有周期性系数的一维 Sturm-Liouville 问题,展示了周期性薛定谔方程在多维情况下的解并对其进行了分类,告诉人们并非所有的解都是布洛赫解。此外,我们还提供了解和准量子的若干性质,并说明了有界解和布洛赫解之间的关系。
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引用次数: 0
Dual-channel photonic crystal fiber dual-parameter sensor exploiting surface plasmon resonance 利用表面等离子体共振的双通道光子晶体光纤双参数传感器
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad7893
Tengfei Xu, Shengli Pu, Siyang Huang and Yu Ji
A surface plasmon resonance (SPR) based sensor using a negative curvature circular side-polished photonic crystal fiber was proposed. The sensor’s sensitivity was analyzed using the finite element method. The impact of structural parameters was investigated. The sensor exhibits an average wavelength sensitivity (WS) of 7846 nm/RIU in the refractive index range of 1.370–1.396 and 2350 nm/RIU in the range of 1.330–1.370, with maximum WS of 46000 nm/RIU. For refractive index and magnetic field dual-parameter sensing, the simultaneously obtained magnetic field sensitivity is 0.84 nm/mT. The proposed SPR sensor demonstrates remarkable sensitivity, making it suitable for refractive index and magnetic field sensing applications.
研究人员提出了一种基于表面等离子体共振(SPR)的传感器,该传感器使用负曲率圆形侧抛光光子晶体光纤。使用有限元法分析了传感器的灵敏度。研究了结构参数的影响。该传感器在折射率 1.370-1.396 范围内的平均波长灵敏度 (WS) 为 7846 nm/RIU,在 1.330-1.370 范围内的平均波长灵敏度 (WS) 为 2350 nm/RIU,最大波长灵敏度 (WS) 为 46000 nm/RIU。在折射率和磁场双参数传感方面,同时获得的磁场灵敏度为 0.84 nm/mT。所提出的 SPR 传感器具有出色的灵敏度,适合折射率和磁场传感应用。
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引用次数: 0
A novel numerical method to solve fractional ordinary differential equations with proportional Caputo derivatives 解决带比例卡普托导数的分数常微分方程的新型数值方法
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad7897
Yogita M Mahatekar and Pushpendra Kumar
In this paper, we develop a novel numerical scheme, namely ‘NPCM-PCDE,’ to integrate fractional ordinary differential equations with proportional Caputo derivatives of the type pcDαu(t) = f1(t, u(t)), t ≥ 0, 0 < α < 1 involving a non-linear operator f1. A new method is developed using a natural discretization of the proportional Caputo derivative and the decomposition method to decompose the non-linear operator f1. The error and stability analyses for the proposed method are provided. Some illustrated examples are given to compare the solution curves graphically with the exact solution and to prove the utility and efficiency of the method. The proposed NPCM-PCDE is found to be efficient, easy to implement, convergent, and stable.
本文开发了一种新的数值方案,即 "NPCM-PCDE",用于积分带有比例卡普托导数的分式常微分方程,其类型为 pcDαu(t) = f1(t, u(t)), t ≥ 0, 0 < α < 1,涉及非线性算子 f1。还给出了一些示例来比较图形解曲线和精确解,以证明该方法的实用性和效率。研究发现,所提出的 NPCM-PCDE 方法高效、易于实现、收敛且稳定。
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引用次数: 0
Investigation into geometric configurations and electronic properties of CeO2-supported gold clusters 研究 CeO2 支持的金簇的几何构型和电子特性
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad77f9
Pengli Shu, Xin Tian, Qiang Guo, Xiaosen Ren, Bohui Zhao, Huanfei Wen, Jun Tang, Yanjun Li, Sugawara Yasuhiro, Zongmin Ma and Jun Liu
A detailed understanding of the geometric structure and electronic properties of gold nanoparticles on the ceria surface is crucial for comprehending their unique catalytic activity. Using the first-principles method based on density functional theory, the adsorption of Aux (x = 1–4) clusters on the CeO2(111) surface was studied. It was discovered that the standing configurations of Au2 and Au3, as well as the tetrahedral structure of Au4, are the most stable adsorption structures. The stability of these configurations is jointly determined by the number and strength of Au-Au bonds, the Au-O bonding energy, and the interaction dynamics between the clusters and the substrate. The analysis of Bader charge, difference charge density and density of states suggested that lattice relaxation and electronic localization occur in the reduced Ce3+. The reduced amount and location of Ce3+ are significantly influenced by the position and charge transfer amount of Aux cluster. The adsorption of CO on Au4/CeO2(111) indicated that stronger Au-C bonding energy due to the hybridization of Au-5d and C-2p, thereby enhancing the catalytic activity for CO oxidation reactions.
详细了解铈表面金纳米粒子的几何结构和电子特性对于理解其独特的催化活性至关重要。利用基于密度泛函理论的第一原理方法,研究了 Aux(x = 1-4)团簇在 CeO2(111)表面的吸附。研究发现,Au2 和 Au3 的站立构型以及 Au4 的四面体结构是最稳定的吸附结构。这些构型的稳定性是由 Au-Au 键的数量和强度、Au-O 键能以及团簇与基底之间的相互作用动力学共同决定的。对 Bader 电荷、差电荷密度和态密度的分析表明,还原 Ce3+ 中存在晶格弛豫和电子局域化。Ce3+ 的还原量和位置受 Aux 簇的位置和电荷转移量的显著影响。CO 在 Au4/CeO2(111)上的吸附表明,由于 Au-5d 和 C-2p 的杂化,Au-C 键的能量更强,从而提高了 CO 氧化反应的催化活性。
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引用次数: 0
A novel image encryption method based on the cycle replacement 基于循环替换的新型图像加密方法
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad7898
Pu Wang, Xiaojun Liu, Jing Xu and Chenhao Lu
For the bit-level image encryption algorithms, pixel values and positions can be changed simultaneously. The operation can enhance the security of image encryption but will require the complicated calculations. Therefore, high security and suitable computation for a new algorithm are needed to be considered. In this paper, a novel image encryption algorithm, which combines the bit-level encryption and the pixel-level encryption methods, is proposed based on the cycle replacement. Firstly, a new 2-dimensional (2D) map with a hyperbolic cosine function (2D-Cosh map) is introduced, which has rich and complex dynamics. Based on the chaotic characteristic of the map, an image encryption algorithm is introduced via the substitution of bit of pixels which can scramble the pixels, and change the image pixel positions effectively. Numerical simulation and security analysis are used to demonstrate the effectiveness and feasibility of the algorithm. From which we can see that the correlation coefficients are almost 0, average entropy = 7.9973, average NPCR = 99.6104%, and average UACI = 33.4664%. It is clear that the algorithm is resistant to differential attacks, interference attacks, and can reduce the correlation of adjacent pixels of the encrypted image greatly. Meanwhile, the algorithm has no limit for the size of a color image in the process of the encryption.
对于位级图像加密算法,像素值和位置可以同时改变。这种操作可以提高图像加密的安全性,但需要进行复杂的计算。因此,需要考虑一种安全性高、计算量合适的新算法。本文提出了一种基于循环置换的新型图像加密算法,它结合了比特级加密和像素级加密方法。首先,本文引入了一种新的具有双曲余弦函数的二维(2D)图(2D-Cosh 图),它具有丰富而复杂的动态特性。基于该图的混沌特性,引入了一种图像加密算法,通过像素位的置换可以扰乱像素,并有效地改变图像像素的位置。通过数值模拟和安全性分析,证明了算法的有效性和可行性。从中可以看出,相关系数几乎为 0,平均熵 = 7.9973,平均 NPCR = 99.6104%,平均 UACI = 33.4664%。由此可见,该算法具有抗差分攻击、抗干扰攻击的能力,可以大大降低加密图像相邻像素的相关性。同时,该算法在加密过程中对彩色图像的大小没有限制。
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引用次数: 0
A novel asymmetric extension of power XLindley distribution: properties, inference and applications to engineering data 幂 XLindley 分布的新型非对称扩展:特性、推理及工程数据应用
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad77fa
Najwan Alsadat, Amal S Hassan, Mohammed Elgarhy, Vasili B V Nagarjuna, Sid Ahmed Benchiha and Ahmed M Gemeay
It is impossible to overstate the importance of using trigonometric functions appropriately in distribution theory. The main contribution of the research is to construct a flexible trigonometric extension of the power XLindley distribution. More specifically, we build an innovative two-parameter lifetime distribution known as the sine power XLindley distribution (SPXLD) using characteristics from the sine-generated family of distributions. As the main motivational fact, it provides an attractive alternative to the power Lindley, power XLindley, weighted Lindley, and extended power Lindley distributions; it may be better able to model lifetime phenomena presenting data of leptokurtic and platkurtic nature. In contrast to the increasing, decreasing, and reversed-j-shaped hazard rate function, the density exhibits asymmetric shapes with varying peakedness levels. Several significant characteristics are illustrated, including moments, the quantile function, the probability density function in series representation, the stress-strength reliability, and incomplete moments. To analyze the behavior of the suggested distribution, sixteen estimation techniques are applied, such as the maximum likelihood, percentiles, some methods of minimum distances, some methods based on minimum and maximum spacing distances, and the Kolmogorov method. After that, an extensive simulation study and the examination of two survival real datasets are used to show the viability, usefulness, and adaptability of the SPXLD. Relevant goodness of fit criteria demonstrates that the SPXLD fits several current distributions.
在分布理论中适当使用三角函数的重要性怎么强调都不为过。本研究的主要贡献在于构建了幂 XLindley 分布的灵活三角扩展。更具体地说,我们利用正弦产生的分布系列的特征,建立了一种创新的双参数寿命分布,即正弦幂 XLindley 分布 (SPXLD)。作为主要的动机事实,它为幂林德雷分布、幂 XLindley 分布、加权林德雷分布和扩展幂林德雷分布提供了一个有吸引力的替代方案;它可能能更好地模拟呈现畸变和铂钝性质数据的寿命现象。与递增、递减和反向 j 型危险率函数相反,密度呈现出峰度水平不同的非对称形状。说明了几个重要特征,包括矩、量子函数、序列表示的概率密度函数、应力-强度可靠性和不完全矩。为了分析建议分布的行为,应用了十六种估计技术,如最大似然法、百分位数法、一些最小距离法、一些基于最小和最大间隔距离的方法以及 Kolmogorov 法。随后,通过广泛的模拟研究和对两个生存真实数据集的检验,展示了 SPXLD 的可行性、实用性和适应性。相关的拟合优度标准表明,SPXLD 适合当前的几种分布。
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引用次数: 0
Contraction of ZX diagrams with triangles via stabiliser decompositions 通过稳定器分解收缩带三角形的 ZX 图
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad6fd8
Mark Koch, Richie Yeung and Quanlong Wang
Recent advances in classical simulation of Clifford+T circuits make use of the ZX calculus to iteratively decompose and simplify magic states into stabiliser terms We improve on this method by studying stabiliser decompositions of ZX diagrams involving the triangle operation. We show that this technique greatly speeds up the simulation of quantum circuits involving multi-controlled gates which can be naturally represented using triangles. We implement our approach in the QuiZX library (2022 A. Kissinger amd J. van de Wetering Quantum Science and Technology7, 044001), (2022 A. Kissinger et al F. Le Gall and T. Morimae, ed. 17th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2022), Leibniz International Proceedings in Informatics (LIPIcs) 232, Schloss Dagstuhl—Leibniz-Zentrum für Informatik, Dagstuhl, Germany, pp 5:1–5:13) and demonstrate a significant simulation speed-up (up to multiple orders of magnitude) for random circuits and a variation of previously used benchmarking circuits. Furthermore, we use our software to contract diagrams representing the gradient variance of parametrised quantum circuits, which yields a tool for the automatic numerical detection of the barren plateau phenomenon in ansätze used for quantum machine learning. Compared to traditional statistical approaches, our method yields exact values for gradient variances and only requires contracting a single diagram. The performance of this tool is competitive with tensor network approaches, as demonstrated with benchmarks against the quimb library (2018 J. Gray Journal of Open Source Software3, 819).
我们通过研究涉及三角形运算的 ZX 图的稳定器分解,改进了这种方法。我们的研究表明,这种技术大大加快了涉及多控制门的量子电路仿真速度,而多控制门可以自然地使用三角形来表示。我们在 QuiZX 库中实现了我们的方法(2022 A. Kissinger amd J. van de Wetering Quantum Science and Technology7, 044001),(2022 A. Kissinger et al F. Le Gall and T. Morimae, eds.17th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2022), Leibniz International Proceedings in Informatics (LIPIcs) 232, Schloss Dagstuhl-Leibniz-Zentrum für Informatik, Dagstuhl, Germany, pp 5:1-5:13),并展示了随机电路和以前使用的基准电路变体的显著模拟速度提升(高达多个数量级)。此外,我们还利用我们的软件收缩了代表参数化量子电路梯度方差的图表,从而产生了一种用于量子机器学习的自动数值检测荒芜高原现象的工具。与传统的统计方法相比,我们的方法能得到梯度方差的精确值,而且只需要收缩一张图。该工具的性能可与张量网络方法相媲美,与 quimb 库(2018 J. Gray Journal of Open Source Software3, 819)的基准测试也证明了这一点。
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引用次数: 0
Quantum transport of topological surface states in presence of circular n-p junctions 存在圆形 n-p 结时拓扑表面态的量子输运
IF 2.9 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1088/1402-4896/ad78c7
Neetu Agrawal
The surface states of topological insulators are characterized by spin-momentum locking, where the electron spin is locked perpendicular to its momentum. This property is preserved under gate potentials which can be used to manipulate spin currents without an external magnetic field enhancing the prospects for spintronic applications. Here, we investigate the scattering of the wave functions of topological surface states within the circular n-p junction positioned on the upper surface of the quintuple-layered three-dimensional topological insulator. With the analytical calculations we explain the scattering of these surface states in such systems.
拓扑绝缘体表面态的特点是自旋-动量锁定,即电子自旋与其动量垂直锁定。这一特性在栅极电势下得以保留,可用于在没有外部磁场的情况下操纵自旋电流,从而增强了自旋电子应用的前景。在这里,我们研究了位于五层三维拓扑绝缘体上表面的圆形 n-p 结内拓扑表面态波函数的散射。通过分析计算,我们解释了这些表面态在此类系统中的散射。
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引用次数: 0
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Physica Scripta
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