Catálogo de publicaciones - revistas

<jats:p>Realization of a flexible and tunable coupling scheme among qubits is critical for scalable quantum information processing. Here, we design and characterize a tunable coupling element based on Josephson junction, which can be adapted to an all-to-all connected circuit architecture where multiple Xmon qubits couple to a common coplanar waveguide resonator. The coupling strength is experimentally verified to be adjustable from 0 MHz to about 40 MHz, and the qubit lifetime can still be up to <jats:inline-formula> <jats:tex-math><?CDATA $12\,{\rm{\mu }}{\rm{s}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>12</mml:mn> <mml:mspace width="0.50em" /> <mml:mi mathvariant="normal">μ</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_8_080305_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> in the presence of the coupling element.</jats:p>

<jats:p>We present a parallel numerical method of simulating the interaction of atoms with a strong laser field by solving the time-depending Schrödinger equation (TDSE) in spherical coordinates. This method is realized by combining constructing block diagonal matrices through using the real space product formula (RSPF) with splitting out diagonal sub-matrices for short iterative Lanczos (SIL) propagator. The numerical implementation of the solver guarantees efficient parallel computing for the simulation of real physical problems such as high harmonic generation (HHG) in these interaction systems.</jats:p>

<jats:p>The photoionization in the frame of the Ammosov–Delone–Krainov theory has been theoretically examined for noble gases, argon, krypton, and xenon, in an elliptically polarized laser field. We consider the intermediate range of the Keldysh parameter, <jats:inline-formula> <jats:tex-math> <?CDATA $\gamma \sim 1$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>γ</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>1</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_8_083201_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, and analyze the influence of shifted ionization potential and temporal profile to eliminate disagreement between theoretical and experimental findings. By including these effects in the ionization rates, we solve rate equations in order to determine an expression for the ionization yield. The use of modified ionization potential shows that the ionization yields will actually decrease below the values predicted by original (uncorrected) formulas. This paper will discuss the causes of this discrepancy.</jats:p>

<jats:p>We perform a theoretical investigation on the control over the atomic excitation of Rydberg states with shaped intense ultrashort laser pulses. By numerically solving the time-dependent Schrödinger equation (TDSE), we systematically study the dependence of the population of the Rydberg states on the <jats:italic>π</jats:italic> phase step position in the frequency spectra of the laser pulse for different intensities, central wavelengths and pulse durations. Our results show that the Rydberg excitation process can be effectively modulated using shaped intense laser pulses with the laser intensity as high as 1×10<jats:sup>14</jats:sup> W/cm<jats:sup>2</jats:sup>. Our work also have benefit to the future investigation to find out the dominant mechanism behind the excitation of Rydberg states in strong laser fields.</jats:p>

<jats:p>Metal–semiconductor Janus nanostructures with asymmetry and directionality have recently aroused significant interest, both in fundamental light–matter interactions mechanism and in technological applications. Here we report the synthesis of different Au–ZnO Janus nanostructures via a facile one-pot colloid method. The growth mechanism is revealed by a series of designed synthesis experiments. The light absorption properties are determined by both the decrease of dipole oscillations of the free electrons and the plasmon-induced hot-electron transfer. Moreover, the finite-difference time-domain (FDTD) simulation method is used to elucidate the electric field distributions of these Janus nanostructures.</jats:p>

<jats:p>Controlling the phase of light in magnetoplasmonic structures is receiving increasing attention because of its already shown capability in ultrasensitive and label-free molecular-level detection. Magneto–optical Kerr reversal has been achieved and well explained in nanodisks by using the phase of localized plasmons. In this paper, we report that the Kerr reversal can also be produced by surface plasmon polaritons independently. We experimentally confirm this in Co and Ag/Co/Ag metal nanogratings, and can give a qualitative explanation that it is the charge accumulation at the interface between the grating surface and air that acts as the electromagnetic restoring force to contribute necessary additional phase for Kerr reversal. Our finding can enrich the means of designing and fabricating magneto–optical-based biochemical sensors.</jats:p>

<jats:p>To reveal the potential aging mechanism for self-irradiation in Pu–Ga alloy, we choose Au–Ag alloy as its substitutional material in terms of its mass density and lattice structure. As a first step for understanding the microscopic behavior of point defects in Au–Ag alloy, we perform a molecular dynamics (MD) simulation on energetics and diffusion of point defects in Au and Ag metal. Our results indicate that the octahedral self-interstitial atom (SIA) is more stable than the tetrahedral SIA. The stability sequence of point defects for He atom in Au/Ag is: substitutional site <jats:inline-formula> <jats:tex-math><?CDATA $\gt $?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>&gt;</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_8_083401_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> octahedral interstitial site <jats:inline-formula> <jats:tex-math><?CDATA $\gt $?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>&gt;</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_8_083401_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> tetrahedral interstitial site. The He–<jats:italic>V</jats:italic> cluster (<jats:inline-formula> <jats:tex-math><?CDATA ${\mathrm{He}}_{n}{V}_{m}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>He</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mrow> <mml:mi>V</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_8_083401_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>, <jats:italic>V</jats:italic> denotes vacancy) is the most stable at <jats:italic>n</jats:italic> = <jats:italic>m</jats:italic>. For the mono-vacancy diffusion, the MD calculation shows that the first nearest neighbour (1NN) site is the most favorable site on the basis of the nudged elastic band (NEB) calculation, which is in agreement with previous experimental data. There are two peaks for the second nearest neighbour (2NN) and the third nearest neighbour (3NN) diffusion curve in octahedral interstitial site for He atom, indicating that the 2NN and 3NN diffusion for octahedral SIA would undergo an intermediate defect structure similar to the 1NN site. The 3NN diffusion for the tetrahedral SIA and He atom would undergo an intermediate site in analogy to its initial structure. For diffusion of point defects, the vacancy, SIA, He atom and He–<jats:italic>V</jats:italic> cluster may have an analogous effect on the diffusion velocity in Ag.</jats:p>

<jats:p>Quasi-classical trajectory (QCT) calculations are reported for the H+LiH (<jats:italic>v</jats:italic> = 0–2, <jats:italic>j</jats:italic> = 0)<jats:inline-formula> <jats:tex-math><?CDATA $\to $?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>→</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_8_083402_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> Li+H<jats:sub>2</jats:sub> reaction on a new ground electronic state global potential energy surface (PES) of the LiH<jats:sub>2</jats:sub> system. Reaction probability and integral cross sections (ICSs) are calculated for collision energies in the range of 0 eV–0.5 eV. Reasonable agreement is found in the comparison between present results and previous available theoretical results. We carried out statistical analyses with all the trajectories and found two main distinct reaction mechanisms in the collision process, in which the stripping mechanism (<jats:italic>i.e.</jats:italic>, without roaming process) is dominated over the collision energy range. The polarization dependent differential cross sections (PDDCSs) indicate that forward scattering dominates the reaction due to the dominated mechanism. Furthermore, the reactant vibration leads to a reduction of the reactivity because of the barrierless and attractive features of PES and mass combination of the system.</jats:p>

<jats:p>The photoionization of a hydrogen atom from its ground state with ultra-fast chirped pulses is investigated by numerically solving the time-dependent Schrödinger equation within length, velocity, and Kramers–Henneberger gauges. Converged results for all gauges for chirp-free pulses agree with the prediction of dynamic interference for ground state hydrogen atoms predicted recently by Jiang and Burgdörfer [<jats:italic>Opt. Express</jats:italic> 26, 19921 (2018)]. In addition, we investigated photoelectron spectra of hydrogen atoms by chirped laser pulses, and showed that dynamic interference effect will be weaken for pulses with increasing linear chirp. Our numerical results can be understood and discussed in terms of an interplay of photoelectron wavepackets from first and second halves of laser enevelop, including the ac Stark energy level shift of the photoelectron final state and atomic stabilization effect at ultra-high intensities.</jats:p>

<jats:p>Multispectral and polarization cameras that can simultaneously acquire the spatial, spectral, and polarization characteristics of an object have considerable potential applications in target detection, biomedical imaging, and remote sensing. In this work, we develop a common-aperture optical system that can capture multispectral and polarization information. An off-axis three-mirror optical system is mounted on the front end of the proposed system and used as a common-aperture telescope in the visible light (400 nm–750 nm) and long-wave infrared (LWIR, <jats:inline-formula> <jats:tex-math><?CDATA $8\,{\rm{\mu }}{\rm{m}}\mbox{--}12\,{\rm{\mu }}{\rm{m}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>8</mml:mn> <mml:mspace width="0.25em" /> <mml:mi mathvariant="normal">μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> <mml:mo>−</mml:mo> <mml:mn>12</mml:mn> <mml:mspace width="0.25em" /> <mml:mi mathvariant="normal">μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_8_084201_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) waveband. The system can maintain a wide field of view (4.5°) and it can demonstrate an enhanced identification ability. The off-axis three-mirror system gets rid of central obscuration while further yielding stable system resolution and energy. Light that has passed through the front-end common-aperture reflection system is divided into the visible light and LWIR waveband by a beamsplitter. The two wavebands then converge on two detectors through two groups of lenses. Our simulation results indicate that the proposed system can obtain clear images in each waveband to meet the diverse imaging requirements.</jats:p>