Catálogo de publicaciones - revistas

<jats:p>The effect of collision energy on the magnetically tuned <jats:sup>6</jats:sup>Li–<jats:sup>6</jats:sup>Li Feshbach resonance (FR) is investigated theoretically by using the coupled-channel (CC) method for the collision energy ranging from 1 μK ⋅ <jats:italic>k</jats:italic> <jats:sub>B</jats:sub> to 100 μK ⋅ <jats:italic>k</jats:italic> <jats:sub>B</jats:sub>. At the collision energy of 1 μK ⋅ <jats:italic>k</jats:italic> <jats:sub>B</jats:sub>, the resonance positions calculated are 543.152 Gs (s wave, the unit 1 Gs = 10<jats:sup>−4</jats:sup> T), 185.109 Gs (p wave |<jats:italic>m<jats:sub>l</jats:sub> </jats:italic>| = 0), and 185.113 Gs (p wave |<jats:italic>m<jats:sub>l</jats:sub> </jats:italic>| = 1), respectively. The p-wave FR near 185 Gs exibits a doublet structure of 4 mGs, associated with dipole–dipole interaction. With the increase of the collision energy, it is found that the splitting width remains the same (4 mGs), and that the resonance positions of s and p waves are shifted to higher magnetic fields with the increase of collision energy. The variations of the other quantities including the resonance width and the amplitude of the total scattering section are also discussed in detail. The thermally averaged elastic rate coefficients at <jats:italic>T</jats:italic> = 10, 15, 20, 25 K are calculated and compared.</jats:p>

<jats:p>Maximal multi-photon entangled states, known as NOON states, play an essential role in quantum metrology. With the number of photons growing, NOON states are becoming increasingly powerful and advantageous for obtaining supersensitive and super-resolved measurements. In this paper, we propose a universal scheme for generating three- and four-photon path-entangled NOON states on a reconfigurable photonic chip via photons subtracted from pairs and detected by heralding counters. Our method is postselection free, enabling phase supersensitive measurements and sensing at the Heisenberg limit. Our NOON-state generator allows for integration of quantum light sources as well as practical and portable precision phase-related measurements.</jats:p>

<jats:p>Laser paint removal in a water environment does not diffuse ablation pollution products into air. Characteristics of water, such as high specific heat and heat flux, generate different effects of the laser paint removal than in an air environment. In this study, the effects of air and water environments on the mechanism and effect of laser paint removal are analyzed and compared experimentally and theoretically. In air, thermodynamic ablation causes removal of paint, whereas in water, stress coupled with plasma shock waves cause tear and splash removal of paint layers after fracture and damage. Fracture and pressure thresholds of the paint and substrate, respectively, indicate the optimum energy density range for laser paint removal in water, providing a reference for engineering applications.</jats:p>

<jats:p>We theoretically investigate the effect of symmetry breaking on the ultrafast plasmon responses of Au nanodisk (ND) dimers by varying the diameter of one of the constituent nanodisks. In the case of a single ultrafast laser pulse, we demonstrate that the ultrafast responses of Au ND homodimer can be significantly modified due to the effect of symmetry breaking. The symmetric dimer shows a single broad spectral peak, whereas the size-asymmetric dimer shows three spectral peaks. The first system displays at most one temporal maximum and no beats in ultrafast temporal, whereas the second system may have three temporal maxima and two beats due to a combination of broken symmetry and the coherent superposition between various plasmon modes induced by the ultra-short laser pulse. Moreover, the shape of temporal dynamics of the size-asymmetric dimer is significantly deformed due to the excitation of local plasmon modes with different wavelength components. Furthermore, the decay time of the amplitude of the local field is longer and oscillates with a high frequency due to the narrower linewidth and red-shifted spectral peaks. We show that the ultrafast plasmon responses of both dimers can be controlled by varying the relative phase and time delays between a pair of two pulses. Our results will open new paths to understanding ultrafast plasmon responses in asymmetric heterodimers with suitable properties for different applications.</jats:p>

<jats:p>A switchable terahertz (THz) polarization converter based on vanadium dioxide (VO<jats:sub>2</jats:sub>) metamaterial is proposed. It is a 5-layer structure which containing metal split-ring-resonator (SRR), the first polyimide (PI) spacer, VO<jats:sub>2</jats:sub> film, the second PI spacer, and metal grating. It is an array structure and the period in <jats:italic>x</jats:italic> and <jats:italic>y</jats:italic> directions is 100 μm. The performance is simulated by using finite integration technology. The simulation results show that, when the VO<jats:sub>2</jats:sub> is in insulating state, the device is a transmission polarization converter. The cross-linear polarization conversion can be realized in a broadband of 0.70 THz, and the polarization conversion rate (PCR) is higher than 99%. Under thermal stimulus, the VO<jats:sub>2</jats:sub> changes from insulating state to metallic state, and the device is a reflective polarization converter. The linear-to-circular polarization conversion can be successfully realized in a broadband of 0.50 THz, and the PCR is higher than 88%.</jats:p>

<jats:p>A quantum key distribution transmitter chip based on hybrid-integration of silica planar light-wave circuit (PLC) and lithium niobates (LN) modulator PLC is presented. The silica part consists of a tunable directional coupler and 400-ps delay line, and the LN part is made up of a Y-branch, with electro-optic modulators on both arms. The two parts are facet-coupled to form an asymmetric Mach–Zehnder interferometer. We successfully encode and decode four BB84 states at 156.25-MHz repetition rate. Fast phase-encoding of 0 or <jats:italic>π</jats:italic> is achieved, with interference fringe visibilities 78.53% and 82.68% for states |+〉 and |–〉, respectively. With the aid of an extra off-chip LN intensity modulator, two time-bin states are prepared and the extinction ratios are 18.65 dB and 15.46 dB for states |0〉 and |1〉, respectively.</jats:p>

<jats:p>Hollow-core negative curvature fibers (HC-NCFs) have become one of the research hotspots in the field of optical fiber because of their potential applications in the data and energy transmissions. In this work, a new kind of single-polarization single-mode HC-NCF with nested U-type cladding elements is proposed. To achieve the single-polarization single-mode transmission, we use two different silica tubes in thickness, which satisfy the resonance and anti-resonance conditions on the U-type cladding elements and the cladding tubes, respectively. Besides, the elliptical elements are introduced to achieve good single-mode performance. By studying the influences of the structure parameters on the propagation characteristics, the optimized structure parameters are obtained. The simulation results show that when the wavelength is fixed at 1550 nm, the single-polarization single-mode transmission is achieved, with the polarization extinction ratio of 25749 and minimum high-order mode extinction ratio of 174. Furthermore, the confinement loss is only 0.0015 dB/m.</jats:p>

<jats:p>Optical nanofiber (ONF) is a special tool to achieve the interaction between light and matter with ultralow power. In this paper, we demonstrate V-type electromagnetically induced transparency (EIT) in cold atoms trapped by an ONF-based two-color optical lattice. At an optical depth of 7.35, 90% transmission can be achieved by only 7.7 pW coupling power. The EIT peak and linewidth are investigated as a function of the coupling optical power. By modulating the pW-level control beam of the ONF-EIT system in sequence, we further achieve efficient and high contrast control of the probe transmission, as well as its potential application in the field of quantum communication and quantum information science by using one-dimensional atomic chains.</jats:p>

<jats:p>Broadband absorption of low-frequency sound waves via a deep subwavelength structure is of great and ongoing interest in research and engineering. Here, we numerically and experimentally present a design of a broadband low-frequency absorber based on an acoustic metaporous composite (AMC). The AMC absorber is constructed by embedding a single metamaterial resonator into a porous layer. The finite element simulations show that a high absorption (absorptance <jats:italic>A</jats:italic> &gt; 0.8) can be achieved within a broad frequency range (from 290 Hz to 1074 Hz), while the thickness of AMC is 1/13 of the corresponding wavelength at 290 Hz. The broadband and high-efficiency performances of the absorber are attributed to the coupling between the two resonant absorptions and the trapped mode. The numerical simulations and experimental results are obtained to be in good agreement with each other. Moreover, the high broadband absorption can be maintained under random incident acoustic waves. The proposed absorber provides potential applications in low-frequency noise reduction especially when limited space is demanded.</jats:p>

<jats:p>Accurate and fast prediction of aerodynamic noise has always been a research hotspot in fluid mechanics and aeroacoustics. The conventional prediction methods based on numerical simulation often demand huge computational resources, which are difficult to balance between accuracy and efficiency. Here, we present a data-driven deep neural network (DNN) method to realize fast aerodynamic noise prediction while maintaining accuracy. The proposed deep learning method can predict the spatial distributions of aerodynamic noise information under different working conditions. Based on the large eddy simulation turbulence model and the Ffowcs Williams–Hawkings acoustic analogy theory, a dataset composed of 1216 samples is established. With reference to the deep learning method, a DNN framework is proposed to map the relationship between spatial coordinates, inlet velocity and overall sound pressure level. The root-mean-square-errors of prediction are below 0.82 dB in the test dataset, and the directivity of aerodynamic noise predicted by the DNN framework are basically consistent with the numerical simulation. This work paves a novel way for fast prediction of aerodynamic noise with high accuracy and has application potential in acoustic field prediction.</jats:p>