Catálogo de publicaciones - revistas

<jats:p>Employing the Pekeris-type approximation to deal with the pseudo-centrifugal term, we analytically study the pseudospin symmetry of a Dirac nucleon subjected to equal scalar and vector modified Rosen–Morse potential including the spin–orbit coupling term by using the Nikiforov–Uvarov method and supersymmetric quantum mechanics approach. The complex eigenvalue equation and the total normalized wave functions expressed in terms of Jacobi polynomial with arbitrary spin–orbit coupling quantum number <jats:italic>k</jats:italic> are presented under the condition of pseudospin symmetry. The eigenvalue equations for both methods reproduce the same result to affirm the mathematical accuracy of analytical calculations. The numerical solutions obtained for different adjustable parameters produce degeneracies for some quantum number.</jats:p>

<jats:p>Eigenspectra that fill regions in the complex plane have been intriguing to many, inspiring research from random matrix theory to esoteric semi-infinite bounded non-Hermitian lattices. In this work, we propose a simple and robust ansatz for constructing models whose eigenspectra fill up generic prescribed regions. Our approach utilizes specially designed non-Hermitian random couplings that allow the co-existence of eigenstates with a continuum of localization lengths, mathematically emulating the effects of semi-infinite boundaries. While some of these couplings are necessarily long-ranged, they are still far more local than what is possible with known random matrix ensembles. Our ansatz can be feasibly implemented in physical platforms such as classical and quantum circuits, and harbors very high tolerance to imperfections due to its stochastic nature.</jats:p>

<jats:p>We propose an efficient quantum private comparison protocol firstly based on one direction quantum walks. With the help of one direction quantum walk, we develop a novel method that allows the semi-honest third party to set a flag to judge the comparing result, which improves the qubit efficiency and the maximum quantity of the participants’ secret messages. Besides, our protocol can judge the size of the secret messages, not only equality. Furthermore, the quantum walks particle is disentangled in the initial state. It only requires a quantum walks operator to move, making our proposed protocol easy to implement and reducing the quantum resources. Through security analysis, we prove that our protocol can withstand well-known attacks and brute-force attacks. Analyses also reveal that our protocol is correct and practical.</jats:p>

<jats:p>Utilizing the geometric phase (GP) acquired in a quantum evolution, we manifest the thermality and quantum nature of the Unruh effect of an accelerating detector. We consider an UDW detector coupling to a conformal field in Minkowski spacetime, whose response spectrum exhibits an intermediate statistics of (1 + 1) anyon field. We find that comparing to an inertial moving detector, the GP in accelerating frame is modified after the nonunitary evolution of the detector due to the Unruh effect. We show that such modification can distinguish the different thermalizing ways of the detector, which depends on the scaling dimension of the conformal primary field. Finally, we estimate the difference between the GP under the Unruh radiation and that in a thermal bath for a static observer, which reveals the quantum origin of the Unruh effect rather than a conventional thermal noise.</jats:p>

<jats:p>The fringe noises disrupt the precise measurement of the atom distribution in the process of the absorption images. The fringe removal algorithms have been proposed to reconstruct the ideal reference images of the absorption images to remove the fringe noises. However, the focus of these fringe removal algorithms is the association of the fringe removal performance with the physical systems, leaving the gap to analyze the workflows of different fringe removal algorithms. This survey reviews the fringe removal algorithms and classifies them into two categories: the image-decomposition based methods and the deep-learning based methods. Then this survey draws the workflow details of two classical fringe removal algorithms, and conducts experiments on the absDL ultracold image dataset. Experiments show that the singular value decomposition (SVD) method achieves outstanding performance, and the U-net method succeeds in implying the image inpainting idea. The main contribution of this survey is the interpretation of the fringe removal algorithms, which may help readers have a better understanding of the research status. Codes in this survey are available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://github.com/leigaoyi/Atomic_Fringe_Denoise" xlink:type="simple">https://github.com/leigaoyi/Atomic_Fringe_Denoise</jats:ext-link>.</jats:p>

<jats:p>As a model molecule of actinide chemistry, UO molecule plays an important role in understanding the electronic structure and chemical bonding of actinide-containing species. We report a study of the laser-induced fluorescence spectra of the U<jats:sup>16</jats:sup>O and U<jats:sup>18</jats:sup>O using two-dimensional spectroscopy. Several rotationally resolved excitation spectra were investigated. Accurate molecular rotational constants and equilibrium internuclear distances were reported. Low-lying electronic states information was extracted from high resolution dispersed fluorescence spectra and analyzed by the ligand field theory model. The configuration of the ground state was determined as U<jats:sup>2+</jats:sup>(5f<jats:sup>3</jats:sup>7s)O<jats:sup>2−</jats:sup>. The branching ratios, and the vibrational harmonic and anharmonic parameters were also obtained. Radiative lifetimes were determined by recording the time-resolved fluorescence spectroscopy. Transition dipole moments were calculated using the branching ratios and the radiative lifetimes. These findings were elucidated by using quantum-chemical calculations, and the chemical bonding was also analyzed. The findings presented in this work will enrich our understanding of actinide-containing molecules.</jats:p>

<jats:p>The oscillator strengths of the valence–shell excitations of C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub> are extremely important for testing theoretical models and studying interstellar gases. In this study, the high-resolution inelastic x-ray scattering (IXS) method is adopted to determine the generalized oscillator strengths (GOSs) of the valence–shell excitations of C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub> at a photon energy of 10 keV. The GOSs are extrapolated to their zero limit to obtain the corresponding optical oscillator strengths (OOSs). Through taking a completely different experimental method of the IXS, the present results offer the high energy limit for electron collision to satisfy the first Born approximation (FBA) and cross-check the previous experimental and theoretical results independently. The comparisons indicate that an electron collision energy of 1500 eV is not enough for C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub> to satisfy the FBA for the large squared momentum transfer, and the line saturation effect limits the accuracy of the OOSs measured by the photoabsorption method.</jats:p>

<jats:p>For both the longitudinal binding force and the lateral binding force, a generic way of controlling the mutual attraction and repulsion (usually referred to as reversal of optical binding force) between chiral and plasmonic hybrid dimers or tetramers has not been reported so far. In this paper, by using a simple plane wave and an onchip configuration, we propose a possible generic way to control the binding force for such hybrid objects in both the near-field region and the far-field region. We also investigate different inter-particle distances while varying the wavelengths of light for each inter-particle distance throughout the investigations. First of all, for the case of longitudinal binding force, we find that chiral-plasmonic hybrid dimer pairs do not exhibit any reversal of optical binding force in the near-field region nor in the far-field region when the wavelength of light is varied in an air medium. However, when the same hybrid system of nanoparticles is placed over a plasmonic substrate, a possible chip, it is possible to achieve a reversal of the longitudinal optical binding force. Later, for the case of lateral optical binding force, we investigate a setup where we place the chiral and plasmonic tetramers on a plasmonic substrate by using two chiral nanoparticles and two plasmonic nanoparticles, with the setup illuminated by a circularly polarized plane wave. By applying the left-handed and the right-handed circular polarization state of light, we also observe the near-field and the far-field reversal of lateral optical binding force for both cases. As far as we know, so far, no work has been reported in the literature on the generic way of reversing the longitudinal optical binding force and the lateral optical binding force of such hybrid objects. Such a generic way of controlling optical binding forces can have important applications in different fields of science and technology in the near future.</jats:p>

<jats:p>We demonstrate an optical frequency comb (OFC) based on a turnkey mode-locked laser with a figure-9-shape structure and polarization-maintaining fibers, for the comparison of frequency among optical clocks with wavelengths of 698 nm, 729 nm, 1068 nm, and 1156 nm. We adopt a multi-branch approach in order to produce high power OFC signals at these specific wavelengths, enabling the signal-to-noise ratio of the beatnotes between the OFC and the clock lasers to exceed 30 dB at a resolution bandwidth of 300 kHz. This approach makes the supercontinuum spectra much easier to be generated than a single branch OFC. However, more out-of-loop fibers degrade the long-term frequency instability due to thermal drift. To minimize the thermal drift effect, we set the fiber lengths of different branches to be similar, and we stabilize the temperature as well. The out-of-loop frequency instability of the OFC due to the incoherence of the multi-branch is about 5.5 × 10<jats:sup>−19</jats:sup> for 4000 s, while the in-loop frequency instability of <jats:italic>f</jats:italic> <jats:sub>ceo</jats:sub> and that of <jats:italic>f</jats:italic> <jats:sub>beat</jats:sub> are 7.5 × 10<jats:sup>−18</jats:sup> for 1 s and 8.5 × 10<jats:sup>−18</jats:sup> for 1 s, respectively. The turnkey OFC meets the requirement for the comparison of frequency between the best optical clocks.</jats:p>

<jats:p>Oxygen ions (O<jats:sup>+</jats:sup>) were implanted into fused silica at a fixed fluence of 1 × 10<jats:sup>17</jats:sup> ions/cm<jats:sup>2</jats:sup> with different ion energies ranging from 10 keV to 60 keV. The surface roughness, optical properties, mechanical properties and laser damage performance of fused silica were investigated to understand the effect of oxygen ion implantation on laser damage resistance of fused silica. The ion implantation accompanied with sputtering effect can passivate the sub-/surface defects to reduce the surface roughness and improve the surface quality slightly. The implanted oxygen ions can combine with the structural defects (ODCs and E′ centers) to reduce the defect densities and compensate the loss of oxygen in fused silica surface under laser irradiation. Furthermore, oxygen ion implantation can reduce the Si–O–Si bond angle and densify the surface structure, thus introducing compressive stress in the surface to strengthen the surface of fused silica. Therefore, the laser induced damage threshold of fused silica increases and the damage growth coefficient decreases when ion energy up to 30 keV. However, at higher ion energy, the sputtering effect is weakened and implantation becomes dominant, which leads to the surface roughness increase slightly. In addition, excessive energy aggravates the breaking of Si–O bonds. At the same time, the density of structural defects increases and the compressive stress decreases. These will degrade the laser laser-damage resistance of fused silica. The results indicate that oxygen ion implantation with appropriate ion energy is helpful to improve the damage resistance capability of fused silica components.</jats:p>