Electrical excitation of surface plasmons

We exploit a plasmon mediated two-step momentum downconversion scheme to convert low-energy tunneling electrons into propagating photons. Surface plasmon polaritons (SPPs) propagating along an extended gold nanowire are excited on one end by low-energy electron tunneling and are then converted to free-propagating photons at the other end. The separation of excitation and outcoupling proofs that tunneling electrons excite gap plasmons that subsequently couple to propagating plasmons. Our work shows that electron tunneling provides a non-optical, voltage-controlled and low-energy pathway for launching SPPs in nanostructures, such as plasmonic waveguide

Random unitary dynamics of quantum networks

We investigate the asymptotic dynamics of quantum networks under repeated applications of random unitary operations. It is shown that in the asymptotic limit of large numbers of iterations this dynamics is generally governed by a typically low dimensional attractor space. This space is determined completely by the unitary operations involved and it is independent of the probabilities with which these unitary operations are applied. Based on this general feature analytical results are presented for the asymptotic dynamics of arbitrarily large cyclic qubit networks whose nodes are coupled by randomly applied controlled-NOT operations.Comment: 4 pages, 2 figure

Equilibrium temperatures of mass transfer cooled walls in high-speed flow of an absorbing-emitting gas

Equilibrium temperatures of mass transfer cooled walls in high speed flow of absorbing-emitting ga

Urban Watershed/Water Body Restoration - The Driving Forces

Urban streams are used for several purposes. Some uses are conflicting and some are complementary. The use of urban water bodies and the resolution of conflicts is driven by anthropogenic and biocentric/ecocentric interests that must be optimized and the conflicts resolved. This article examines and analyzes land ethics (biocentric) and socio-economic (anthropocentric) drives for stream restoration of urban watersheds located in the Milwaukee (WI) metropolitan area. The basins experienced increased flooding, significant degradation of sediment and water quality, and loss of aquatic species, all due to urbanization. It was found that the primary drivers for restoration of urban streams are the ethical attitudes of population towards the ecocentric benefits of restoration in combination with a desire for flood control. A Contingent Valuation Survey of citizens residing in two Milwaukee watersheds revealed that those who see the watershed in ecocentric terms appear to have a greater Willingness to Pay for watershed/water body improvements than those who see the benefits solely in anthropogenic terms of reduction of flood damages

High-Resolution Near-Field Raman Microscopy of Single-Walled Carbon Nanotubes

We present near-field Raman spectroscopy and imaging of single isolated single-walled carbon nanotubes with a spatial resolution of ≈25  nm. The near-field origin of the image contrast is confirmed by the measured dependence of the Raman scattering signal on tip-sample distance and the unique polarization properties. The method is used to study local variations in the Raman spectrum along a single single-walled carbon nanotube

Ab initio theory of Fano resonances in plasmonic nanostructures and metamaterials

An ab initio theory for Fano resonances in plasmonic nanostructures and metamaterials is developed using Feshbach formalism. It reveals the role played by the electromagnetic modes and material losses in the system, and enables the engineering of Fano resonances in arbitrary geometries. A general formula for the asymmetric resonance in a non-conservative system is derived. The influence of the electromagnetic interactions on the resonance line shape is discussed and it is shown that intrinsic losses drive the resonance contrast, while its width is mostly determined by the coupling strength between the non-radiative mode and the continuum. The analytical model is in perfect agreement with numerical simulations.Comment: 13 pages, 5 figure