Growing partially directed self-avoiding walks

A partially directed self-avoiding walk model with the 'kinetic growth' weighting is solved exactly, on the square lattice and for two restricted, strip geometries. Some finite-size effects are examined

Dynamics of Nonequilibrium Deposition with Diffusional Relaxation

Models of adhesion of extended particles on linear and planar substrates are of interest in interpreting surface deposition in colloid, polymer, and certain biological systems. An introduction is presented to recent theoretical advances in modeling these processes. Effects of diffusional relaxation are surveyed in detail, including results obtained by analytical, large-scale numerical, mean-field and scaling approaches.Comment: Review article to appear in Annual Reviews in Computational Physics; 24 pages in plain TeX + 4 PostScript figure

Initial Decoherence of Open Quantum Systems

We present a new short-time approximation scheme for evaluation of decoherence. At low temperatures, the approximation is argued to apply at intermediate times as well. It then provides a tractable approach complementary to Markovian-type approximations, and is appropriate for evaluation of deviations from pure states in quantum computing models.Comment: 24 pages in plain Te

Topics in Quantum Dynamics and Coherence for Quantum Information Processing

We outline selected trends and results in theoretical modeling of quantum systems in support of the developing research field of quantum information processing. The resulting modeling tools have been applied to semiconductor materials and nanostructures that show promise for implementation of coherent, controlled quantum dynamics at the level of registers of several quantum bits (qubits), such as spins. Many-body field-theoretical techniques have been utilized to address a spectrum of diverse research topics. Specifically, the theory of decoherence and more generally the origin and effects of quantum noise and the loss of entanglement in quantum dynamics of qubits and several-qubit registers has been advanced. Qubit coupling mechanisms via the indirect exchange interaction have been investigated, and quantum computing designs have been evaluated for scalability. We outline general and specific research challenges, the solution of which will advance the field of modeling "open quantum systems" to further our understanding of how environmental influences affect quantum coherence and its loss during quantum dynamics

Exact Results for 1D Conserved Order Parameter Model

Recent exact results for a particle-exchange model on a linear lattice, with only irreversible moves reducing the local energy allowed, are reviewed. This model describes a zero-temperature Kawasaki-type phase separation process which reaches a frozen, initial-condition-dependent state at large times.Comment: nine pages, plain Te

Fluctuating Interfaces, Surface Tension, and Capillary Waves: An Introduction

We present an introduction to modern theories of interfacial fluctuations and the associated interfacial parameters: surface tension and surface stiffness, as well as their interpretation within the capillary wave model. Transfer matrix spectrum properties due to fluctuation of an interface in a long-cylinder geometry are reviewed. The roughening transition and properties of rigid interfaces below the roughening temperature in 3d lattice models are surveyed with emphasis on differences in fluctuations and transfer matrix spectral properties of rigid vs. rough interfaces.Comment: 21 page

Morphology of Fine-Particle Monolayers Deposited on Nanopatterned Substrates

We study the effect of the presence of a regular substrate pattern on the irreversible adsorption of nanosized and colloid particles. Deposition of disks of radius $r_0$ is considered, with the allowed regions for their center attachment at the planar surface consisting of square cells arranged in a square lattice pattern. We study the jammed state properties of a generalized version of the random sequential adsorption model for different values of the cell size, $a$, and cell-cell separation, $b$. The model shows a surprisingly rich behavior in the space of the two dimensionless parameters $\alpha=a/2r_0$ and $\beta=b/2r_0$. Extensive Monte Carlo simulations for system sizes of $500\times500$ square lattice unit cells were performed by utilizing an efficient algorithm, to characterize the jammed state morphology.Comment: 11 pages, 10 figures, 3 table

Three-Dimensional Percolation Modeling of Self-Healing Composites

We study the self-healing process of materials with embedded "glue"-carrying cells, in the regime of the onset of the initial fatigue. Three-dimensional numerical simulations within the percolation-model approach are reported. The main numerical challenge taken up in the present work, has been to extend the calculation of the conductance to three-dimensional lattices. Our results confirm the general features of the process: The onset of the material fatigue is delayed, by developing a plateau-like time-dependence of the material quality. We demonstrate that in this low-damage regime, the changes in the conductance and thus, in similar transport/response properties of the material can be used as measures of the material quality degradation. A new feature found for three dimensions, where it is much more profound than in earlier-studied two-dimensional systems, is the competition between the healing cells. Even for low initial densities of the healing cells, they interfere with each other and reduce each other's effective healing efficiency.Comment: 15 pages in PDF, with 6 figure