- 标题
- 摘要
- 关键词
- 实验方案
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Concurrence of two identical atoms in a rectangular waveguide: linear approximation with single excitation
摘要： Waveguide electrodynamics has been attracted much attention; however, a waveguide with a cross section has seldom considered. We study two two-level systems (TLSs) interacting with a reservoir of guided modes con?ned in a rectangular waveguide of a cross section. For the energy separation of the identical TLSs far away from the cutoff frequencies of transverse modes, the delay differential equations are obtained with single-excitation initial in the TLSs. We accurately solved the delay differential equations for the TLSs interacting with either single transverse mode or double transverse modes of the waveguide. The retarded character of multiple reemissions and reabsorptions of photons between the TLSs is revealed, and the effects of the inter-TLS distance on the time evolution of the concurrence of the TLSs is examined.
关键词： Dipolar approximation,Entanglement,One-dimensional waveguide,Two two-level atoms,Rotating wave approximation,Concurrence
更新于2025-09-16 10:30:52
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Compact Equal-Width Equal-Length Phase Shifter With Slow-Wave Half-Mode Substrate Integrated Waveguide for 5G Applications
摘要： The emerging fifth-generation (5G) wireless and mobile communications demand high-performance phase shifters to enable the multi-channel transmit/receive systems with phase control ability. In this work, a size-miniaturized wideband phase shifter based on slow-wave half-mode substrate integrated waveguide (SW-HMSIW) is presented. The proposed SW-HMSIW is consisting of conventional HMSIW section and periodically-patterned non-uniform microtrip polyline unit cells. Patterning polyline unit cells in HMSIW can effectively enhance the product of the equivalent permittivity and permeability of SW-HMSIW, so that the slow-wave effect can be exhibited and its associated size reduction will be further achieved. Moreover, lengths and widths of segments of the proposed polyline unit cell can influence the equivalent permittivity and permeability of the SW-HMSIW, and consequently change its phase constant and cutoff frequency. Hence, for a SW-HMSIW with a fixed physical length, an electrical length variation, i.e, phase shift, can be achieved as segments of the polyline employ various lengths or widths. Based on this principle, a wideband equal-width equal-length SW-HMSIW phase shifter is implemented. Measured results are in good agreement with simulated ones, with a phase shift of 90.5 ± 3 degree and a fractional bandwidth of 43.0% achieved. Compared with some similar reported works, the proposed one shows a size reduction more than 80% as well as good magnitude and phase deviations performance. Moreover, its miniaturized size and equal-width equal-length structure make it suitable for the complex multi-channel modules and networks of the 5G applications.
关键词： slow-wave structure,phase shifter,Effective medium approximation,size miniaturization,half-mode substrate integrated waveguide (HMSIW)
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Including the Effects of Covering Layers in the Determination of Graphene Conductivity from THz-TDS Measurements
摘要： We investigate the effects of covering layers on the determination of graphene conductivity from THz-TDS measurements. Especially the errors arising from the common approach to neglect those layers in the determination process are addressed. To counteract those errors an expanded determination method, based on the classical thin-film approach is introduced.
关键词： thin-film approximation,graphene conductivity,THz-TDS measurements,covering layers
更新于2025-09-16 10:30:52
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Robust and automatic modeling of tunnel structures based on terrestrial laser scanning measurement
摘要： The terrestrial laser scanning technology is increasingly applied in the deformation monitoring of tunnel structures. However, outliers and data gaps in the terrestrial laser scanning point cloud data have a deteriorating effect on the model reconstruction. A traditional remedy is to delete the outliers in advance of the approximation, which could be time- and labor-consuming for large-scale structures. This research focuses on an outlier-resistant and intelligent method for B-spline approximation with a rank (R)-based estimator, and applies to tunnel measurements. The control points of the B-spline model are estimated specifically by means of the R-estimator based on Wilcoxon scores. A comparative study is carried out on rank-based and ordinary least squares methods, where the Hausdorff distance is adopted to analyze quantitatively for the different settings of control point number of B-spline approximation. It is concluded that the proposed method for tunnel profile modeling is robust against outliers and data gaps, computationally convenient, and it does not need to determine extra tuning constants.
关键词： Terrestrial laser scanning,health monitoring,rank-based estimator,B-spline approximation,robust modeling
更新于2025-09-16 10:30:52
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Detection of a mixed bipartite entangled state in arbitrary dimension via a structural physical approximation of partial transposition
摘要： It is crucial to know whether the quantum state generated in the experiment is entangled. In the literature, this topic was studied extensively and researchers proposed different approaches for the detection of a mixed bipartite entangled state in arbitrary dimension. Proceeding in this line of research, we propose three different criteria for the detection of mixed bipartite negative partial transpose (NPT) entangled state in arbitrary dimension. Our criteria are based on the method of structural physical approximation (SPA) of partial transposition (PT). We show that the proposed criteria for the detection of a NPT entangled state can be realized experimentally. Two of the proposed criteria are given in terms of the concurrence of the given state in arbitrary dimension so it is essential to ?nd out the concurrence. Thus, we provide lower and upper bounds of concurrence of the quantum state under investigation in terms of average ?delity of two quantum states, and hence these bounds can be realized experimentally. Moreover, we show how to perform a SPA map on a qutrit-qubit system and then explicitly calculate the matrix elements of the density matrix describing the SPA-PT of the qutrit-qubit system. We then illustrate our criteria for the detection of entanglement by considering a class of qubit-qubit system and a class of qutrit-qubit system.
关键词： partial transposition,concurrence,average fidelity,mixed bipartite entangled state,entanglement detection,structural physical approximation
更新于2025-09-16 10:30:52
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Light Pressure on an Inhomogeneous Spherical Particle in the Field of Laser Tweezers
摘要： The light pressure on an inhomogeneous spherical dielectric particle consisting of a shell and a core with different refractive indices is considered. The forces acting on this particle in a laser beam with a Gaussian intensity profile have been found in the geometrical optics approximation. The radiation propagation is analyzed by taking into account the different refractive indices of the core, the shell, and the medium surrounding the particle. The light pressure is shown to depend significantly on the core radius, which allows the core size to be estimated from the spatial dynamics of the particle in the field of optical tweezers.
关键词： laser tweezers,refractive indices,inhomogeneous spherical particle,geometrical optics approximation,light pressure
更新于2025-09-16 10:30:52
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Photoelectron holography from multiple-return backscattering electron orbits
摘要： We theoretically investigate the photoelectron momentum distributions of a diatomic molecule in a linearly polarized two-color laser ?eld by solving the time-dependent Schr?dinger equation. An upward curvature interference pattern is found in the two-dimensional photoelectron momentum spectra. Resorting to a simple semiclassical analysis and the strong-?eld approximation theory, we show that the interference pattern corresponds to a holographic pattern from the second-return backscattering electron orbits and, furthermore, the underlying physics of the distinct observation of such interference pattern is revealed. The holographic patterns from the backscattering electron orbits with the different return times may encode the information of the target structure at different times after ionization.
关键词： strong-?eld approximation theory,backscattering electron orbits,time-dependent Schr?dinger equation,photoelectron holography
更新于2025-09-16 10:30:52
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[IEEE 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - Barcelona, Spain (2019.9.2-2019.9.6)] 2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE - Evaluation of Electromagnetic Noise Radiated from Tube-type LED Lamps and Its Effect on Wireless Medical Telemetry Systems
摘要： Light-emitting diode (LED) lamps have been widely introduced in the healthcare field. On the other hand, electromagnetic interference with wireless medical telemetry systems by switched-mode power supplies built in LED lamps has been a serious problem. We have investigated electromagnetic noise radiated from bulb-type LED lamps and its effect on wireless medical telemetry systems. In this study, we focus on tube-type LED lamps and investigated the statistical characteristics of electromagnetic noise radiated from them. Additionally, the critical reception of wireless medical telemetry systems subjected to interference by tube-type LED lamp installation was investigated.
关键词： light-emitting diode (LED),Gaussian approximation,receiver sensitivity,switched-mode power supply,wireless medical telemetry system,impulsive noise,electromagnetic interference (EMI)
更新于2025-09-16 10:30:52
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Wulff-Based Approach to Modeling the Plasmonic Response of Single Crystal, Twinned, and Core–Shell Nanoparticles
摘要： The growing interest in plasmonic nanoparticles and their increasingly diverse applications is fuelled by the ability to tune properties via shape control, promoting intense experimental and theoretical research. Such shapes are dominated by geometries that can be described by the kinetic Wulff construction such as octahedra, thin triangular platelets, bipyramids, and decahedra, to name a few. Shape is critical in dictating the optical properties of these nanoparticles, in particular their localized surface plasmon resonance behavior, which can be modeled numerically. One challenge of the various available computational techniques is the representation of the nanoparticle shape. Specifically, in the discrete dipole approximation, a particle is represented by discretizing space via an array of uniformly distributed points-dipoles; this can be difficult to construct for complex shapes including those with multiple crystallographic facets, twins, and core?shell particles. Here, we describe a standalone user-friendly graphical user interface (GUI) that uses both kinetic and thermodynamic Wulff constructions to generate a dipole array for complex shapes, as well as the necessary input files for DDSCAT-based numerical approaches. Examples of the use of this GUI are described through three case studies spanning different shapes, compositions, and shell thicknesses. Key advances offered by this approach, in addition to simplicity, are the ability to create crystallographically correct structures and the addition of a conformal shell on complex shapes.
关键词： localized surface plasmon resonance,Wulff construction,plasmonic nanoparticles,shape control,graphical user interface,DDSCAT,discrete dipole approximation
更新于2025-09-16 10:30:52
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Significant OSNR Improvement in Intensity Modulation and Coherent Detection Metro Links Enabled by Advanced Nonlinear DSP
摘要： In recent years, low-rank based tensor completion, which is a higher order extension of matrix completion, has received considerable attention. However, the low-rank assumption is not sufficient for the recovery of visual data, such as color and 3D images, when the ratio of missing data is extremely high. In this paper, we consider “smoothness” constraints as well as low-rank approximations and propose an efficient algorithm for performing tensor completion that is particularly powerful regarding visual data. The proposed method admits significant advantages, owing to the integration of smooth PARAFAC decomposition for incomplete tensors and the efficient selection of models in order to minimize the tensor rank. Thus, our proposed method is termed as “smooth PARAFAC tensor completion (SPC).” In order to impose the smoothness constraints, we employ two strategies, total variation (SPC-TV) and quadratic variation (SPC-QV), and invoke the corresponding algorithms for model learning. Extensive experimental evaluations on both synthetic and real-world visual data illustrate the significant improvements of our method, in terms of both prediction performance and efficiency, compared with many state-of-the-art tensor completion methods.
关键词： low-rank tensor approximation,PARAFAC model,CP model,smoothness,quadratic variation,total variation (TV),Tensor completion for images
更新于2025-09-16 10:30:52