Entanglement entropy of one-dimensional gases

We introduce a systematic framework to calculate the bipartite entanglement entropy of a spatial subsystem in a one-dimensional quantum gas which can be mapped into a noninteracting fermion system. To show the wide range of applicability of the proposed formalism, we use it for the calculation of the entanglement in the eigenstates of periodic systems, in a gas confined by boundaries or external potentials, in junctions of quantum wires, and in a time-dependent parabolic potential.     

Supramolecular Polymeric Macrocyclic Receptors – Hybrid Carrier versus Channel Transporters in Bulk Liquid Membranes

The synthesis of heteroditopic macrocyclic ureido-receptors is described. NMR studies show the formation of self-organized oligomeric superstructures. Membrane transport experiments show a direct relation between the self-assembling and the transport properties of these molecular information transfer devices. The self-organization of these receptors may provide the first evidence for the possible hybrid transport carrier versus channel mechanisms in liquid membranes.     

Temperature induced single-crystal-to-single-crystal transformations and structure directed effects on magnetic properties

The binding of CoII, NiII, and CuII cations to the lithium 3-pyridinesulfonate ligand in an aqueous solution leads to single crystals of coordination polymers 1-3. The solid-state architectures of 1-3 which resulted from the combination of ligand-water heterocomplexation processes are linear coordination polymers packed into parallel alternatively stratified layers. These layers are interconnected through intermolecular hydrogen-bonding interactions occurring between the coordinated water molecules and the noncoordinating oxygen atoms of the sulfonate groups. Consequently, this leads to the formation of the cross-linked 3D (1, 2) or layered 2D (3) networks exhibiting 12-point or four-point hydrogen bond contacts between each unit with eight or four adjacent neighbors, respectively. The reversible structural rearrangement of these frameworks proceeds from the "relaxed" room-temperature phase to the "contracted" low-temperature phase in response to an external thermal stimulus. The reversibility of the contraction/relaxation process has been tested and confirmed by X-ray analysis. Motions toward shortening intermolecular distances have the consequence of increasing the degree of magnetic interaction between the metal ions. The magnetic measurements carried out in the range 1.8-400 K on the three compounds show an unusual change from antiferromagnetic to ferromagnetic behavior related to the structural variations recorded at low temperatures and to the loss of water above 350 K.     

Nano Mapper: an Internet knowledge mapping system for nanotechnology development

Nanotechnology research has experienced rapid growth in recent years. Advances in information technology enable efficient investigation of publications, their contents, and relationships for large sets of nanotechnology-related documents in order to assess the status of the field. This paper presents the development of a new knowledge mapping system, called Nano Mapper (), which integrates the analysis of nanotechnology patents and research grants into a Web-based platform. The Nano Mapper system currently contains nanotechnology-related patents for 1976–2006 from the United States Patent and Trademark Office (USPTO), European Patent Office (EPO), and Japan Patent Office (JPO), as well as grant documents from the U.S. National Science Foundation (NSF) for the same time period. The system provides complex search functionalities, and makes available a set of analysis and visualization tools (statistics, trend graphs, citation networks, and content maps) that can be applied to different levels of analytical units (countries, institutions, technical fields) and for different time intervals. The paper shows important nanotechnology patenting activities at USPTO for 2005–2006 identified through the Nano Mapper system.     

Vibronic coupling parameters and Stokes shift in thiogallate phosphors

This article is devoted to the problem of the electron-vibrational interaction in 4f-5d optical transitions and the calculation of the Stokes shift in thiogallate materials. Usually 4f-5d transitions give rise to the broad vibronic bands whose shape-function have been described and found, including terms corresponding to the emission (absorption) from both ground and first excited levels. This approximation can be applied not only at low temperatures, but at high temperatures also, including room temperature, when the most photoluminescence (PL) measurements are carried out. We estimate vibronic coupling parameters and make the fitting of experimental data for Ba, Ca and Sr thiogallates. The peculiarity of Stokes shift is discussed. The theoretical results are in good agreement with the experimental data.     

Laterally-corrugated ridge-waveguide distributed feedback lasers at 980 nm

The paper presents a simulation-based analysis of laterally-corrugated ridge-waveguide distributed feedback semiconductor lasers emitting at 980 nm. The simulations were performed using software developed in-house and the PICS3D software package from Crosslight Software Inc. The effects of the corrugation geometry, phase-shift section, and mirror reflectivities on single longitudinal mode operation are discussed. The lasers, designed along the guidelines derived from the simulation results, were fabricated by using molecular beam epitaxy for wafer growth and low-cost nano-imprint lithography. They exhibited stable single-mode operation with up to 50 dB side-mode suppression ratio.