Catálogo de publicaciones - revistas

<jats:p>The statistical model for community detection is a promising research area in network analysis. Most existing statistical models of community detection are designed for networks with a known type of community structure, but in many practical situations, the types of community structures are unknown. To cope with unknown community structures, diverse types should be considered in one model. We propose a model that incorporates the latent interaction pattern, which is regarded as the basis of constructions of diverse community structures by us. The interaction pattern can parameterize various types of community structures in one model. A collapsed Gibbs sampling inference is proposed to estimate the community assignments and other hyper-parameters. With the Pitman–Yor process as a prior, our model can automatically detect the numbers and sizes of communities without a known type of community structure beforehand. Via Bayesian inference, our model can detect some hidden interaction patterns that offer extra information for network analysis. Experiments on networks with diverse community structures demonstrate that our model outperforms four state-of-the-art models.</jats:p>

<jats:p>Multi-path (or multi-mode) entanglement has been proved to be a useful resource for sub-shot-noise sensitivity of phase estimation, which has aroused much research interest inquantum metrology recently. Various schemes of multi-path interferometers based on optical systems have been put forward. Here, we study a multi-state interferometer with multi-level atoms by projective measurements. Specifically, we investigate its ultimate sensitivity described by quantum Fisher information theory and find that the Cramer–Rao bound can be achieved. In particular, we investigate a specific scheme to improve the sensitivityof magnetometery with a three-state interferometry delivered by a single nitrogen-vacancy (NV) center of diamond with tailor pulses. The impacts of imperfections of the atomic beam-splitter, described by the three-level quantum Fourier transform, on the sensitivity of phase estimation is also discussed.</jats:p>

<jats:p>This article presents the design and performance of a terahertz on-chip coupled-grounded coplanar waveguide (GCPW) power combiner using a 50μm-thick InP process. The proposed topology uses two coupled-GCPW lines at the end of the input port to substitute two quarter-wavelength GCPW lines,which is different from the conventional Wilkinson power combiner and canavailably minimize the coverage area. According to the results obtained, forthe frequency range of 210–250z, the insertion losses for each two-waycombiner and four-way combiner were lower than 1.05 dB and 1.35 dB,respectively, and the in-band return losses were better than 11 dB. Moreover,the proposed on-chip GCPW-based combiners achieved a compromise in low-loss, broadband, and small-size, which can find wide applications in terahertz bands, such as power amplifiers and signal distribution networks.</jats:p>

<jats:p>A novel instrument that integrates reflection high energy electron diffraction (RHEED), electron energy loss spectroscopy (EELS), and imaging is designed and simulated. Since it can correlate the structural, elemental, and spatial information of the same surface region via the simultaneously acquired patterns of RHEED, EELS, and energy-filtered electron microscopy, it is named correlative reflection electron microscopy (c-REM). Our simulation demonstrates that the spatial resolution of this c-REM is lower than 50 nm, which meets the requirements for <jats:italic>in-situ</jats:italic> monitoring the structural and chemical evolution of surface in advanced material.</jats:p>

<jats:p>A 32-channel wavelength division multiplexer with 100 GHz spacing is designed and fabricated by interleaving two silicon arrayed waveguide gratings (AWGs). It has a parallel structure consisting of two silicon 16-channel AWGs with 200 GHz spacing and a Mach–Zehnder interferometer (MZI) with 200 GHz free spectral range. The 16 channels of one silicon AWG are interleaved with those of the other AWG in spectrum, but with an identical spacing of 200 GHz. For the composed wavelength division multiplexer, the experiment results reveal 32 wavelength channels in C-band, a wavelength spacing of 100 GHz, and a channel crosstalk lower than –15 dB.</jats:p>

<jats:p>A series of Sr<jats:sub>2</jats:sub>MgSi<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>:Tb<jats:sup>3+</jats:sup> nanophosphors is prepared using a high-temperature solid-state reaction. The x-ray diffraction patterns show that the crystal structure of the sample is not significantly affected by Tb<jats:sup>3+</jats:sup> ions. However, the images of the scanning electron microscope illustrate that the average size of nanoparticles becomes larger with the increase of Tb<jats:sup>3+</jats:sup> concentration. Unlike earlier investigations on down-conversion emission of Tb<jats:sup>3+</jats:sup> ion excited by deep ultraviolet light, in this work, the photoluminescence characteristics of Sr<jats:sub>2</jats:sub>MgSi<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub> nanophosphors doped with different Tb<jats:sup>3+</jats:sup> concentrations are analyzed under 374-nm excitations. The intense green emission at 545 nm is observed at an optimal doping concentration of 1.6 mol%. The main reason for the concentration quenching is due to the electric dipole–electric dipole interaction among Tb<jats:sup>3+</jats:sup> ions.</jats:p>

<jats:p>Coherent superposition of electronic states induces attosecond electron motion in molecules. We theoretically investigate the strong-field ionization of this superposition state by numerically solving the time-dependent Schrödinger equation. In the obtained photoelectron momentum distribution, an intriguing bifurcation structure appears in the strong-field holographic interference pattern. We demonstrate that this bifurcation structure directly provides complete information about the status of the transient wave function of the superposition state: the horizontal location of the bifurcation in the momentum distribution reveals the relative phase of the involved components of the superposition state and the vertical position indicates the relative coefficient. Thus, this bifurcation structure takes a snapshot of the transient electron wave packet of the superposition state and provides an intuitive way to monitor electron motion in molecules.</jats:p>

<jats:p>Coherent electronic dynamics are of great significance in photo-induced processes and molecular magnetism. We theoretically investigate electronic dynamics of triatomic molecule <jats:inline-formula> <jats:tex-math> <?CDATA ${\rm{H}}_{3}^{2+}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">H</mml:mi> <mml:mn>3</mml:mn> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_30_12_123203_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> by circularly polarized pulses, including electron density distributions, induced electronic currents, and ultrafast magnetic field generation. By comparing the results of the coherent resonant excitation and direct ionization, we found that for the coherent resonant excitation, the electron is localized and the coherent electron wave packet moves periodically between three protons, which can be attributed to the coherent superposition of the ground A′ state and excited E<jats:sup>+</jats:sup> state. Whereas, for the direct single-photon ionization, the induced electronic currents mainly come from the free electron in the continuum state. It is found that there are differences in the intensity, phase, and frequency of the induced current and the generated magnetic field. The scheme allows one to control the induced electronic current and the ultrafast magnetic field generation.</jats:p>

<jats:p>Based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) method, similar models are employed to simultaneously calculate the first-order and second-order Zeeman coefficients as well as the hyperfine interaction constants of the related energy levels of <jats:sup>27</jats:sup>Al<jats:sup>+</jats:sup> and its logical ions <jats:sup>9</jats:sup>Be<jats:sup>+</jats:sup> and <jats:sup>25</jats:sup>Mg<jats:sup>+</jats:sup> in the <jats:sup>27</jats:sup>AI<jats:sup>+</jats:sup> optical clock. With less than 0.34% deviations from experimental values in Zeeman coefficients of <jats:sup>27</jats:sup>Al<jats:sup>+</jats:sup>, these calculated parameters will be of great help for better evaluation of the systematic uncertainty. We also calculate the isotope shift parameters of the related energy levels, which could extend our knowledge and understanding of nuclear properties of these ions.</jats:p>

<jats:p>Based on the model- and data-driven strategy, a spectroscopy learning method that can extract the novel and hidden information from the line list databases has been applied to the R branch emission spectra of 3–0 band of the ground electronic state of <jats:sup>12</jats:sup>C<jats:sup>16</jats:sup>O. The labeled line lists such as line intensities and Einstein <jats:italic>A</jats:italic> coefficients quoted in HITRAN2020 are collected to enhance the dataset. The quantified spectroscopy-learned spectroscopic constants is beneficial for improving the extrapolative accuracy beyond the measurements. Explicit comparisons are made for line positions, line intensities, Einstein <jats:italic>A</jats:italic> coefficients, which demonstrate that the model- and data-driven spectroscopy learning approach is a promising and an easy-to-implement strategy.</jats:p>