Dual-frequency output of wireless power transfer system with single inverter using improved differential evolution algorithm

In wireless charging devices, a transmitter that applies a single inverter to output dual-frequency can effectively solve the charging incompatibility problem caused by different wireless charging standards and reduce the equipment volume. However, it is very difficult to solve the switching angle of the modulated dual-frequency waveform, which involves non-linear high-dimensional multi-objective optimization with multiple constraints. In this paper, an improved differential evolution (DE) algorithm is proposed to solve the transcendental equations of switching angle trains of dual-frequency programmed harmonic modulation (PHM) waveform. The proposed algorithm maintains diversity while preserving the elites and improves the convergence speed of the solution. The advantage of the proposed algorithm was verified by comparing with non-dominated sorting genetic algorithm II (NSGA II) and multi-objective particle swarm optimization (MOPSO). The simulation and experimental results validate that the proposed method can output dual-frequency with a single inverter for wireless power transfer (WPT).Web of Science139art. no. 220

Evolution of the Surface Structures on SrTiO3_3(110) Tuned by Ti or Sr Concentration

The surface structure of the SrTiO$_3$(110) polar surface is studied by scanning tunneling microscopy and X-ray photoelectron spectroscopy. Monophased reconstructions in (5$\times$1), (4$\times$1), (2$\times$8), and (6$\times$8) are obtained, respectively, and the evolution between these phases can be tuned reversibly by adjusting the Ar$^{+}$ sputtering dose or the amount of Sr/Ti evaporation. Upon annealing, the surface reaches the thermodynamic equilibrium that is determined by the surface metal concentration. The different electronic structures and absorption behaviors of the surface with different reconstructions are investigated.Comment: 10 pages, 14 figure

Metasurface computing components that support dual channel parallel processing and provide full type logic gate options

The logic gate components based on electromagnetic waves are crucial for building a digital computing platform with batch computing and low-cost energy consumption requirements. However, most of the reported logic gates have only one computational channel and have a single function. In order to improve the channel capacity and versatility of logic gates, we design a simple and compact graphene metasurface for dual channel parallel computing, with each channel's function being switchable across all types of logic functions. In the design, we combine the advantages of reconfigurable metasurfaces and polarization sensitive metasurfaces. Based on the polarization sensitive characteristics, we integrate two polarization logic gates into a single device. These two polarization logic gates can work simultaneously, and the crosstalk between them is 0. Based on the reconfigurable feature, the functions of both logic gates can be freely selected from NOT, AND, NAND, OR, NOR, XOR and XNOR. So, this component can achieve simultaneous operation of any two logical functions, and there are 49 combinations available. Our design philosophy provides inspiration for achieving ultra fast and high-density integrated signal processing

High-quality superconducting α-Ta film sputtered on the heated silicon substrate

Abstract Intrigued by the discovery of the long lifetime in the α-Ta/Al2O3-based Transmon qubit, researchers recently found α-Ta film is a promising platform for fabricating multi-qubits with long coherence time. To meet the requirements for integrating superconducting quantum circuits, the ideal method is to grow α-Ta film on a silicon substrate compatible with industrial manufacturing. Here we report the α-Ta film sputter-grown on Si (100) with a low-loss superconducting TiNx buffer layer. The α-Ta film with a large growth temperature window has a good crystalline character. The superconducting critical transition temperature (Tc) and residual resistivity ratio (RRR) in the α-Ta film grown at 500 °C are higher than that in the α-Ta film grown at room temperature (RT). These results provide crucial experimental clues toward understanding the connection between the superconductivity and the materials' properties in the α-Ta film and open a new route for producing a high-quality α-Ta film on silicon substrate for future industrial superconducting quantum computers

High-quality superconducting {\alpha}-Ta film sputtered on heated silicon substrate

Intrigued by the discovery of the long lifetime in the {\alpha}-Ta/Al2O3-based Transmon qubit, researchers recently found {\alpha}-Ta film is a promising platform for fabricating multi-qubits with long coherence time. To meet the requirements for integrating superconducting quantum circuits, the ideal method is to grow {\alpha}-Ta film on silicon substrate compatible with industrial manufacturing. Here we report the {\alpha}-Ta film sputter-grown on Si (100) with low-loss superconducting TiNx buffer layer. The pure-phase {\alpha}-Ta film with a large growth temperature window has good crystalline character. The critical temperature (Tc) and residual resistance ration (RRR) in the {\alpha}-Ta film grown at 500 oC are higher than that in the {\alpha}-Ta film grown at room temperature. These results provide crucial experimental clues towards understanding the connection between the superconductivity and the materials' properties in the {\alpha}-Ta film, and open a new route for producing high-quality {\alpha}-Ta film on silicon substrate for future industrial superconducting quantum computer

Non-Volatile Reconfigurable Compact Photonic Logic Gates Based on Phase-Change Materials

Photonic logic gates have important applications in fast data processing and optical communication. This study aims to design a series of ultra-compact non-volatile and reprogrammable photonic logic gates based on the Sb2Se3 phase-change material. A direct binary search algorithm was adopted for the design, and four types of photonic logic gates (OR, NOT, AND, and XOR) are created using silicon-on-insulator technology. The proposed structures had very small sizes of 2.4 μm × 2.4 μm. Three-dimensional finite-difference time-domain simulation results show that, in the C-band near 1550 nm, the OR, NOT, AND, and XOR gates exhibit good logical contrast of 7.64, 6.1, 3.3, and 18.92 dB, respectively. This series of photonic logic gates can be applied in optoelectronic fusion chip solutions and 6G communication systems

Ultra-Compact and Broadband Nano-Integration Optical Phased Array

The on-chip nano-integration of large-scale optical phased arrays (OPAs) is a development trend. However, the current scale of integrated OPAs is not large because of the limitations imposed by the lateral dimensions of beam-splitting structures. Here, we propose an ultra-compact and broadband OPA beam-splitting scheme with a nano-inverse design. We employed a staged design to obtain a T-branch with a wavelength bandwidth of 500 nm (1300–1800 nm) and an insertion loss of −0.2 dB. Owing to the high scalability and width-preserving characteristics, the cascaded T-branch configuration can significantly reduce the lateral dimensions of an OPA, offering a potential solution for the on-chip integration of a large-scale OPA. Based on three-dimensional finite-difference time-domain (3D FDTD) simulations, we demonstrated a 1 × 16 OPA beam-splitter structure composed entirely of inverse-designed elements with a lateral dimension of only 27.3 μm. Additionally, based on the constructed grating couplers, we simulated the range of the diffraction angle θ for the OPA, which varied by 0.6°–41.6° within the wavelength range of 1370–1600 nm

Low-frequency fluctuations of a mid-infrared quantum cascade laser operating at cryogenic temperatures

International audienceThis work demonstrates that mid-infrared quantum cascade lasers operating under external optical feedback can output a chaotic dynamics through low-frequency fluctuations close to 77 K. Results also show that the birth of chaotic dynamics is not limited to near-threshold pumping levels. In addition, when the semiconductor material is cooled down from room temperature to 77 K, it is found that the laser destabilization takes place at a lower feedback ratio which proves that quantum cascade lasers are sensitive to temperatures, likely due to changes in the upper state lifetime. These examinations are meaningful for chaotic operation of quantum cascade lasers in secure atmospheric transmission lines and optical countermeasure systems