Decoherence: A Closed-System Approach

The aim of this paper is to review a new perspective about decoherence, according to which formalisms originally devised to deal just with closed or open systems can be subsumed under a closed-system approach that generalizes the traditional account of the phenomenon. This new viewpoint dissolves certain conceptual difficulties of the orthodox open-system approach but, at the same time, shows that the openness of the quantum system is not the essential ingredient for decoherence, as commonly claimed. Moreover, when the behavior of a decoherent system is described from a closed-system perspective, the account of decoherence turns out to be more general than that supplied by the open-system approach, and the quantum-to-classical transition defines unequivocally the realm of classicality by identifying the observables with classical-like behavior.     

Control Strategy of True Time Delay Lines

This article presents the control of adjustable true time delays applied to an optical beamforming system. First is introduced the response of ring resonators of two and four ports and the cascade and lattice structures. The coupling factor and the phase modulation are employed as the control parameters for the adjustable group delay. The strategy of control is proposed and applied to a cascade of five ring resonators for producing wideband true time delays in the picosecond–nanosecond range with 2-GHz bandwidth and extremely low ripple. Ripples lower than 0.1% were obtained for the adjusted group delays. The proposed strategy can be simply extended if more resonators are added to increase the bandwidth of the system.     

Shape Matters: Anisotropy of the Morphology of Inorganic Colloidal Particles – Synthesis and Function

The shape of a crystalline particle can be defined by a characteristic set and abundance of surfaces corresponding to the lattice planes [hkl] of the crystal. The structure, the density, the electronic system, and the energy of each [hkl]‐surface is different from the others. Consequently, every morphology is also characterized by a unique free energy compared to alternative shapes at a constant surface‐to‐volume ratio. Using tools from geometrical crystallography, an attempt is made to describe the systems in terms of morphology energy landscapes. It is obvious that, similar to surface phenomena, shape‐related properties are also apparent, in particular at the nanometer‐scale. However, morphology effects go much beyond surface effects. It will be shown that not only catalytic properties differ with particle shape, but also magnetic, optical, electronic, mechanical, and self‐assembly properties are influenced. In addition, analytical methods are highlighted that are suitable for the determination of the shape of the particles. Different methods are discussed that can be found for the synthesis of anisotropic metal and metal‐oxide nanoparticles.     

Boolean Percolation on Doubling Graphs

Journal of Statistical Physics - We consider the discrete Boolean model of percolation on weighted graphs satisfying a doubling metric condition. We study sufficient conditions on the distribution...     

FROM 1,3-DIPHOSPHETANE-2,4-DIYLS TO CYCLIC ANIONS AND CATIONS

The interest in diradicals has grown by the increasing number of stable diradicals which have been synthesized during the last few years. The diphosphacyclobutane-diyles have a diradicaloid molecular structure and they were the first diradicals to be prepared in the gramme scale. The combination of stability and high yield synthesis creates the opportunity both to change the substitution pattern or to prepare different valence isomers. Current experimental and computational studies reveal that electron transfer reactions of maintain the cyclic system. In the contribution, the oxidation reaction of 1 to the radical cation 2 and the cyclic diphosphaallyl cation 3 will be reported. Additionally, the remarkable mechanism of the reaction of 1 at first to the radical anion 4 but particularly to the diphosphacyclobutadiene dianion 5 under reductive conditions will be presented in detail.