Universally-composable finite-key analysis for efficient four-intensity decoy-state quantum key distribution

We propose an efficient four-intensity decoy-state BB84 protocol and derive concise security bounds for this protocol with the universally composable finite-key analysis method. Comparing with the efficient three-intensity protocol, we find that our efficient four-intensity protocol can increase the secret key rate by at least $30\%$. Particularly, this increasing rate of secret key rate will be raised as the transmission distance increases. At a large transmission distance, our efficient four-intensity protocol can improve the performance of quantum key distribution profoundly.Comment: accepted by Eur. Phys. J.

Hygienic Property and Water Resistance of Waterborne Polyacrylate/Flower-like ZnO Composite Coatings

Content: Polyacrylate as film-forming materials has been widely used in leather finishing, but its compactness significantly obstructs the hygienic property of upper leather. Therefore, considerable efforts have been made to endow polyacrylate with required properties. In this study, we demonstrated a facile and rapid sonochemical process to synthesis the flower-like ZnO nanostructures. The related morphology and structure of product were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Meanwhile, flower-like ZnO were introduced into the polyacrylate matrix by physical blending method, whose morphology, latex stability, water vapor permeability and water resistance were measured. The results showed that flower-like ZnO assembled by ellipsoid-like nanorods with the length of about 600 nm was successfully fabricated. The sizes of flower-like ZnO were 1.2 μm. According to SEM images, flower-like ZnO evenly dispersed were observed in composite matrix. Compared with pure polyacrylate, polyacrylate/flower-like ZnO composites exhibited the superior stability. Meanwhile, its water vapor permeability and water resistancewere increased by 52.91% and 53.13%, severally. The reason for this is that ZnO with rough structure can increase voids in polyacrylate film and thus improving hygienic property of polyacrylate film. Additionally, the hydrophilic groups on surface of ZnO can product the crosslinking with polyacrylate chains, which contributed to the enhancement of water resistance. Thus, a promising coating with hygienic property and water resistance for leather finishing agent was approved. Take-Away: 1. Polyacrylate/flower-like ZnO composites exhibited excellent hygienic property. 2. This composite coating achieves simultaneous enhancement in water vapor permeability and water resistance. 3. The morphology of ZnO can effect the properties of polyacrylate

Copper atomic contacts exposed to water molecules

Monatomic and molecular hydrogen and also oxygen, as well as water molecules and OH that are exposed to atomic copper in intimate contact have been studied theoretically using computational methods. The authors optimized moderately large structures of Cu/H/Cu, Cu/HCuH/Cu, Cu/H$_2$/Cu, Cu/H$_2$O/Cu, Cu/OH/Cu, Cu/O/Cu, Cu/O$_2$/Cu, and calculated appropriate values for conductance and inelastic tunneling spectroscopy (IETS) properties of the contact junctions; elucidating them as being a possible outcome resulting from the exposure of copper electrodes to the atomic/molecular contaminant species. Here we also demonstrate the IETS properties, by means of ab-initio calculations, that can determine the form of the junction geometries. Furthermore, we identify the bonding geometries at the interfaces of the copper electrodes that directly give rise to the specific IETS signatures that have been observed in recent experiments. Based on low-bias conductance and IETS calculations, for the specific case of water exposure of copper electrodes, it was concluded that a single hydrogen or a single oxygen atom bridging the copper electrodes is not responsible for the high conductance peak measurements. Regarding Model 4, where an individual water molecule is considered to be the bridging constituent, our computational results suggest that it has a relatively low probability of being an appropriate candidate. Based upon current computational results, the two hydrogens in Model 3 appear to be in molecular form, although they still form a bond with the adjacent copper atoms. Comparing computational with experimental results indicates that Model 3 is in acceptable agreement with available data.Comment: 5 pages, 2 figure