Hyperfine induced spin and entanglement dynamics in Double Quantum Dots: A homogeneous coupling approach

We investigate hyperfine induced electron spin and entanglement dynamics in a system of two quantum dot spin qubits. We focus on the situation of zero external magnetic field and concentrate on approximation-free theoretical methods. We give an exact solution of the model for homogeneous hyperfine coupling constants (with all coupling coefficients being equal) and varying exchange coupling, and we derive the dynamics therefrom. After describing and explaining the basic dynamical properties, the decoherence time is calculated from the results of a detailed investigation of the short time electron spin dynamics. The result turns out to be in good agreement with experimental data.Comment: 10 pages, 8 figure

Perturbative regimes in central spin models

Central spin models describe several types of solid state nanostructures which are presently considered as possible building blocks of future quantum information processing hardware. From a theoretical point of view, a key issue remains the treatment of the flip-flop terms in the Hamiltonian in the presence of a magnetic field. We systematically study the influence of these terms, both as a function of the field strength and the size of the spin baths. We find crucial differences between initial states with central spin configurations of high and such of low polarizations. This has strong implications with respect to the influence of a magnetic field on the flip-flop terms in central spin models of a single and more than one central spin. Furthermore, the dependencies on bath size and field differ from those anticipated so far. Our results might open the route for the systematic search for more efficient perturbative treatments of central spin problems.Comment: 7 pages, 3 figure

Appreciating ADR\u27s Global Role with Good Governance

Alternative dispute resolution is surging around the world given its parallels to and provision critically needed governance. International practitioners are interviewed to identify the most noteworthy trends and concerns. Will ADR erode or elevate good governance

Facilitative ADR\u27s Global Popularity and Promise

This article presents the results of research evaluating the effectiveness of cross cultural leadership to dispute resolution process in the Balkans, Cameroon, Nepal and Ukraine. Unexpectedly, universal themes emerge that passionately advocate facilitative and inclusive multicultural dispute resolution. At the very least, they call for closer scrutiny and consideration of facilitative dispute resolution\u27s global potential

Influence of chopped laser light onto the electronic transport through atomic-sized contacts

This article reports on the influence of laser irradiation onto the electrical conductance of gold nanocontacts established with the mechanically controllable breakjunction technique (MCB). We concentrate here on the study of reversible conductance changes which can be as high as 200%. We investigate the dependence on the initial conductance of the contacts, the wavelength, the intensity and position of the laser spot with respect to the sample. Under most conditions an enhancement of the conductance is observed. We discuss several physical mechanisms which might contribute to the observed effect including thermal expansion, rectification and photon-assisted transport. We conclude that thermal expansion is not the dominating one.Comment: 20 pages with 7 figures; conference contribution on the 9th near field optics conference 2006 in Lausanne, Switzerland; accepted by the Journal of Microscop

Influence of nano-mechanical properties on single electron tunneling: A vibrating Single-Electron Transistor

We describe single electron tunneling through molecular structures under the influence of nano-mechanical excitations. We develop a full quantum mechanical model, which includes charging effects and dissipation, and apply it to the vibrating C$_{60}$ single electron transistor experiment by Park {\em et al.} {[Nature {\bf 407}, 57 (2000)].} We find good agreement and argue vibrations to be essential to molecular electronic systems. We propose a mechanism to realize negative differential conductance using local bosonic excitations.Comment: 7 pages, 6 figure

It often howls more than it chugs: Wind versus ship noise under water in Australia’s maritime regions

Marine soundscapes consist of cumulative contributions by diverse sources of sound grouped into: physical (e.g., wind), biological (e.g., fish), and anthropogenic (e.g., shipping)—each with unique spatial, temporal, and frequency characteristics. In terms of anthropophony, shipping has been found to be the greatest (ubiquitous and continuous) contributor of low-frequency underwater noise in several northern hemisphere soundscapes. Our aim was to develop a model for ship noise in Australian waters, which could be used by industry and government to manage marine zones, their usage, stressors, and potential impacts. We also modelled wind noise under water to provide context to the contribution of ship noise. The models were validated with underwater recordings from 25 sites. As expected, there was good congruence when shipping or wind were the dominant sources. However, there was less agreement when other anthropogenic or biological sources were present (i.e., primarily marine seismic surveying and whales). Off Australia, pristine marine soundscapes (based on the dominance of natural, biological and physical sound) remain, in particular, near offshore reefs and islands. Strong wind noise dominates along the southern Australian coast. Underwater shipping noise dominates only in certain areas, along the eastern seaboard and on the northwest shelf, close to shipping lanes

Editorial: Impacts of shipping on marine fauna

About 80% of international trade goods are transported by ships (UNCTAD, 2019)..

Developing Reasoned Framework for International Choice with Criminal Procedure

While scholars fiercely debate retributive versus restorative justice within the U.S. criminal system, the international community is quietly, steadily and creatively combining the two. Fortunately, enough case study material exists to begin identifying a rational framework to guide future procedural choice

Existence of positive solutions of a superlinear boundary value problem with indefinite weight

We deal with the existence of positive solutions for a two-point boundary value problem associated with the nonlinear second order equation $u''+a(x)g(u)=0$. The weight $a(x)$ is allowed to change its sign. We assume that the function $g\colon\mathopen{[}0,+\infty\mathclose{[}\to\mathbb{R}$ is continuous, $g(0)=0$ and satisfies suitable growth conditions, so as the case $g(s)=s^{p}$, with $p>1$, is covered. In particular we suppose that $g(s)/s$ is large near infinity, but we do not require that $g(s)$ is non-negative in a neighborhood of zero. Using a topological approach based on the Leray-Schauder degree we obtain a result of existence of at least a positive solution that improves previous existence theorems.Comment: 12 pages, 4 PNG figure