Search

This paper reports a high temperature superconducting (HTS) microstrip equalizer for improving the flatness of the pass-band group delay of an HTS filter for third-generation (3G) communications. The HTS filter to be equalized is a ten-pole quasi-elliptic function filter with a bandwidth of 9.6 MHz centered at 1946.5 MHz. The one-port coupled-resonator microstrip equalizers were designed to have three or four poles, and the calculated and simulated group delay response curves of the filter with the equalizers are presented and discussed. A three-pole equalizer was fabricated on a piece of 0.5 mm thick MgO wafer with double-sided YBCO films. The measured responses show that after connecting with the HTS equalizer, the group-delay effective bandwidth of the filter, defined as the ratio between the flat group delay pass-band width (a criterion of variation of pass-band group delay being less than 50 ns was applied) and the equal ripple pass-band width, increased from 50% to 70% without any noticeable degradation of the band-edge steepness of the HTS filter. [ABSTRACT FROM AUTHOR]

The electronic properties and relative stability of zigzag graphene nanoribbons are studied by varying the percentage of hydroxyl radicals for edge saturation using first principle calculations. The passivated structures of zigzag graphene nanoribbon have spin-polarized ground state with antiferromagnetic exchange coupling across the edge and ferromagnetic coupling along the edges. When the edges are specially passivated by hydroxyl, the potentials of spin exchange interaction across the two edges shift accordingly, resulting into a spin-semiconductor. Varying the concentration of hydroxyl groups can alter the maximum magnetization splitting. When the percentage of asymmetrically adsorbed hydroxyl reaches 50%, the magnetization splitting can reach a value as high as 275 meV due to the asymmetrical potential across the nanoribbon edges. These results would favor spintronic device applications based on zigzag graphene nanoribbons. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the thickness-dependent morphologies of gold when deposited by thermal evaporation on graphenes. It involves the use of the micromechanical cleavage of natural graphite through Scotch transparent tape. It reveals that the layer number of graphenes influences the interaction of gold on n-layer graphenes to substrates.

Large coupling strengths in exciton-photon interactions are important for the quantum photonic network, while strong cavity-quantum dot interactions have been focused on s-shell excitons with small coupling strengths. Here we demonstrate strong interactions between cavities and p-shell excitons with a great enhancement by the in situ wave-function control. The p-shell excitons are demonstrated with much larger wave-function extents and nonlocal interactions beyond the dipole approximation. Then the interaction is tuned from the nonlocal to the local regime by the wave function shrinking, during which the enhancement is obtained. A large coupling strength of 210 μeV has been achieved, indicating the great potential of p-shell excitons for coherent information exchange. Furthermore, we propose a distributed delay model to quantitatively explain the coupling strength variation, revealing the intertwining of excitons and photons beyond the dipole approximation. [ABSTRACT FROM AUTHOR]

Two-photon Rabi splitting in a cavity-dot system provides a basis for multiqubit coherent control in a quantum photonic network. Here we report on two-photon Rabi splitting in a strongly coupled cavity-dot system. The quantum dot was grown intentionally large in size for a large oscillation strength and small biexciton binding energy. Both exciton and biexciton transitions couple to a high-quality-factor photonic crystal cavity with large coupling strengths over 130 μeV. Furthermore, the small binding energy enables the cavity to simultaneously couple with two exciton states. Thereby, two-photon Rabi splitting between the biexciton and cavity is achieved, which can be well reproduced by theoretical calculations with quantum master equations. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate a metamaterial structure composed of two mirror-symmetric joint split ring resonators (JSRRs) that support extremely sharp trapped-mode resonance with a large modulation depth in the terahertz region. Contrary to the regular mirror-arranged SRR arrays in which both the subradiant inductive-capacitive (LC) resonance and quadrupole-mode resonance can be excited, our designed structure features a metallic microstrip bridging the adjacent SRRs, which leads to the emergence of an otherwise inaccessible ultrahigh-quality-factor resonance. The ultrasharp resonance occurs near the Wood-Rayleigh anomaly frequency, and the underlying mechanism can be attributed to the strong coupling between the in-plane propagating collective lattice surface mode originating from the array periodicity and localized surface plasmon resonance in mirror-symmetric coupled JSRRs, which dramatically reduces radiative damping. The ultrasharp resonance shows great potential for multifunctional applications such as plasmonic switching, low-power nonlinear processing, and chemical and biological sensing. [ABSTRACT FROM AUTHOR]

The article presents information on the functionalization of BN nanotubes. The studies on BN nanotubes have been initiated due to the striking structural similarity between graphitic carbon and hexagonal BN. The comparison between the two systems is of significant interest with respect to the development of functional nanomaterials and nanodevices. Researchers selected fluorine-functionalized BN nanotubes in order to pursue applications in nanoelectronics. Fluorination is one of the most effective pathways to affect transport properties. They examined the direct reaction between BN nanotubes and fluorine or hydrogen fluoride.

In the emerging field of nanobiotechnology, further downsizing the fluidic channels to the nanometer scale is attractive for both fundamental studies and technical applications. The insulation Silicon nitride membrane nanofluidic channel array which have width∼75nm and depth ∼ 100nm and length 50μm were created by focused-ion- beam instrument, theλ--DNA molecules were put inside them and the dynamic characteristics were initial studied, a fluorescence microscopy was used to observe the images. We observed λ--DNA moved inside the nanotrenches which dealt with activating reagent Brij aqueous solution only by capillary force,this will help us to understand more DNA dynamics characteristics and more information about single biomolecule transporting through a nanopore,.