Catálogo de publicaciones - revistas

<jats:p> <jats:italic>To measure the parameters of fiber and to visualize the reshaping process of fiber in air tunnel, an experimental approach is developed in the present work. The tunnel is designed with gradient flow velocity, and the fiber reshaping images as well as the fiber length value are obtained experimentally. An analytical expression of velocity distribution in the tunnel is theoretically derived and the simulated results are obtained. Automatic fiber reshaping including stretch and rotation is verified using the dynamical equation and the multi-spherical chain model. It is shown that pull force by air flow makes a chain of balls become straight and Stokes moment makes the ball chain rotate. Finally, reshaping criterion related with flow velocity is formulated.</jats:italic> </jats:p>

<jats:p>We propose and demonstrate a high efficiency broadband near infrared single-photon upconversion and detection with a broadband pump laser based on sum frequency conversion in the PPLN crystal. By using a pump laser centered at 1040 nm with a spectral bandwidth of 10 nm, the signal single-photons centered at 1562 nm with a broadband bandwidth up to 7.2 nm are frequency-converted from the near infrared to the visible regime. A maximum conversion efficiency of 18.8% is achieved, while the background noise is measured to be only 1.2 × 10<jats:sup>−3</jats:sup> counts/pulse. The corresponding spectral linewidth of the upconverted photons is 0.2 nm. This scheme of broadband infrared single-photon upconversion and detection provides potential solutions in infrared laser ranging, broadband infrared imaging and quantum key distribution.</jats:p>

<jats:p> <jats:italic>We demonstrate that the etalon effects of alkali cells can be used as the output coupler of an alkali laser. Based on a rubidium cell with highly parallelized windows, a 2.7 W rubidium laser with optical efficiency of 20.9% and slope efficiency of 31.8% is obtained by adopting unconventional output couplers. Since it has compact configuration and the inner surface of the rubidium cell is uncoated, this may be used in high power laser systems with long lifetimes.</jats:italic> </jats:p>

<jats:p> <jats:italic>High-dimensional (HD) entanglement provides a very promising way of transcending the limitations of the two-dimensional entanglement between qubits for increasing channel capacity in many quantum protocols. In the pursuit of capitalizing on the HD entangled states, one of the central issues is to unambiguously and comprehensively quantify and reconstruct them. The full quantum state tomography is a unique solution, but it is undesirable and even impractical because the measurements increase rapidly in <jats:italic>d</jats:italic> <jats:sup>4</jats:sup> for a bipartite <jats:italic>d</jats:italic>-dimensional quantum state. Here we present a very efficient and practical tomography method—asymptotical locking tomography (ALT), which can harvest full information of bipartite <jats:italic>d</jats:italic>-dimensional entangled states by very few measurements less than 2<jats:italic>d</jats:italic> <jats:sup>2</jats:sup> only. To showcase the validity and reasonableness of our ALT, we carry out the test with the two-photon spin-orbital angular momentum hyperentangled states in a four-dimensional subspace. Besides high-efficiency and practicality, our ALT is also universal and can be generalized into multipartite HD entanglement and other quantum systems.</jats:italic> </jats:p>

<jats:p> <jats:italic>Sound propagation properties of a duct system with Helmholtz resonators (HRs) are affected by mean flow. Previous studies have tended to focus on the effects of mean flows on acoustic response of a duct system with a finite number of HRs. Employing an empirical impedance model, we present a modified transfer matrix method for studying the effect of mean flow on the complex band structure of an air duct system with an infinite periodic array of HRs. The efficiency of the modified transfer matrix is demonstrated by comparison between an example of transmission response calculation for a finite single HR loaded duct and the finite element simulation result calculated using the COMSOL software. Numerical results are presented to analyze the effect of mean flow on the band structure and transmission loss of the sound wave in the duct system. It is hoped that this study will provide theoretical guidance for acoustic wave propagation of HR silencer in the presence of mean flow.</jats:italic> </jats:p>

<jats:p> <jats:italic>Bulk Cu/V multilayers simultaneously possess high strength and excellent radiation resistance thanks to their high density of interfaces. Irradiation-induced atomic mixing of Cu/V multilayers has been less investigated. Here, we investigate the ion irradiation of bulk Cu/V multilayers exposed to <jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{H}}}_{2}^{+}$?></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>2</mml:mn> <mml:mo>+</mml:mo> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_37_3_036101_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> or He<jats:sup>+</jats:sup> ions at 350°C. The microstructure and elemental distribution are investigated by transmission electron microscopy and energy dispersive x-ray spectroscopy. Facetted bubbles and atomic mixing are observed after ion irradiation. The possible mechanisms of irradiation-induced atomic mixing are discussed.</jats:italic> </jats:p>

<jats:p> <jats:italic>We systematically investigate the internal friction properties of a Fe–(43 at.%)Al powder mixture compact during the heating process with the expectation to understand the phase formation and transition process. Three internal friction peaks are successively observed during the heating process from room temperature to 750°C, but almost completely disappear in the subsequent cooling process. Three internal friction peaks exhibit obvious measuring frequency dependence, which increases with decreasing the frequency. The first internal friction peak originates from the micro-sliding of weak bonding interface between Al particles corresponding to a recrystallization process of deformed Al particles. The second internal friction peak is attributed to a phase formation process associated with the formation of the intermediate phase Fe<jats:sub>2</jats:sub>Al<jats:sub>5</jats:sub>. The third internal friction peak is considered to result from the formation of the FeAl intermetallic compound owing to the reaction of Fe<jats:sub>2</jats:sub>Al<jats:sub>5</jats:sub> and residual Fe initiated by a dramatic thermal explosion reaction</jats:italic>.</jats:p>

<jats:p> <jats:italic>A Bose–Einstein condensate with a large atom number is an important experimental platform for quantum simulation and quantum information research. An optical dipole trap is the a conventional way to hold the ultracold atoms, where an atomic cloud is evaporatively cooled down before reaching the Bose–Einstein condensate. A carefully designed trap depth controlling curve is typically required to realize the optimal evaporation cooling. We present and demonstrate a simple way to optimize the evaporation cooling in a crossed optical dipole trap. A polyline shape optical power control profile is easily obtained with our method, by which a pure Bose–Einstein condensate with atom number 1.73 × 10<jats:sup>5</jats:sup> is produced. Theoretically, we numerically simulate the optimal evaporation cooling using the parameters of our apparatus based on a kinetic theory. Compared to the simulation results, our evaporation cooling shows a good performance. We believe that our simple method can be used to quickly realize evaporation cooling in optical dipole traps</jats:italic>.</jats:p>

<jats:p> <jats:italic>We propose a coupling model to describe the interaction between the bright and dark modes of the plasmons of a dimer composed of two orthogonal gold nano-rods (GNRs), referred to as the BDMC model. This model shows that the eigen-frequencies of the coupled plasmons are governed by Coulomb potential and electrostatic potential. With the BDMC model, the behaviors of the coupling coefficient and the frequency offset, which is a new parameter introduced here, are revealed. Meanwhile, the asymmetric behavior of two eigen-frequencies related to gap of two GNRs is explained. Using the harmonic oscillator model and the coupled parameters obtained by the BDMC model, the bright mode absorption spectra of the dimer are calculated and the results agree with the numerical simulation</jats:italic>.</jats:p>

<jats:p> <jats:italic>We try to use Ho doping combined with band modulation to adjust the thermoelectric properties for BiCuSeO. The results show that Ho doping can increase the carrier concentration and increase the electrical conductivity in the whole temperature range. Although Seebeck coefficient decreases due to the increase of carrier concentration, it still keeps relatively high values, especially in the middle and high temperature range. On this basis, the band-modulation sample can maintain relatively higher carrier concentration while maintaining relatively higher mobility, and further improve the electrical transporting performance. In addition, due to the introduction of a large number of interfaces in the band-modulation samples, the phonon scattering is enhanced effectively and the lattice thermal conductivity is reduced. Finally, the maximal power factor (PF) of 5.18 μW⋅cm<jats:sup>−1</jats:sup>K<jats:sup>−2</jats:sup> and the dimensionless thermoelectric figure of merits (ZT) of 0.81 are obtained from the 10% Ho modulation doped sample at 873 K.</jats:italic> </jats:p>