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Random sequential adsorption (RSA) models have been studied due to their relevance to deposition processes on surfaces. The depositing particles are represented by hard-core extended objects; they are not allowed to overlap. Numerical Monte Carlo studies and analytical considerations are reported for 1D and 2D models of multilayer adsorption processes. Deposition without screening is investigated, in certain models the density may actually increase away from the substrate. Analytical studies of the late stage coverage behavior show the crossover from exponential time dependence for the lattice case to the power law behavior in the continuum deposition. 2D lattice and continuum simulations rule out some "exact" conjectures for the jamming coverage. For the deposition of dimers on a 1D lattice with diffusional relaxation we find that the limiting coverage (100%) is approached according to the ~1/t**0.5 power-law preceded, for fast diffusion, by the mean-field crossover regime with the intermediate ~1/t behavior. In case of k-mer deposition (k>3) with diffusion the void fraction decreases according to the power-law t**[-1/(k-1)]. In the case of RSA of lattice hard squares in 2D with diffusional relaxation the approach to the full coverage is ~t**(-0.5)., 5 pages (plain LaTeX)

Biochemical computing is an emerging field of unconventional computing that attempts to process information with biomolecules and biological objects using digital logi c. In this work we survey filtering in general, in biochemical computing, and summarize the experimental realization of an AND logic gate with sigmoid response in one of the inputs. The logic gate is realized with electrode-immobilized glucose-6-phosphate dehydrogena se enzyme that catalyzes a reaction corresponding to the Boolean AND functions. A kinetic mode l is also developed and used to evaluate the extent to which the performa nce of the experimentally realized logic gate is close to optimal., The Clarkson team acknowledges support by NSF (CCF-0726698 and CCF-1015983, DMR-0706209), by ONR (N00014-08-1-1202), and by SRC (2008-RJ-1839G). The Auburn team acknowledges support from the USDA-CSREES (2006-34394-16953). The work in Spain (M.P.) was funded by Ramon y Cajal program, MICINN. Additionally, this material is based on the work (A.S.) which was supported by NSF, while working (A.S.) at the Foundation.

We review results on evaluation of loss of information in quantum registers due to their interactions with the environment. It is demonstrated that an optimal measure of the level of quantum noise effects can be introduced via the maximal absolute eigenvalue norm of deviation of the density matrix of a quantum register from that of ideal, noiseless dynamics. For a semiconductor quantum dot charge qubits interacting with acoustic phonons, explicit expressions for this measure are derived. For a broad class of environmental modes, this measure is shown to have the property that for small levels of quantum noise it is additive and scales linearly with the size of the quantum register.

We offer a theoretical design of new systems that show promise for digital biochemical computing, including realizations of error correction by utilizing redundancy, as well as signal rectification. The approach includes information processing using encoded DNA sequences, DNAzyme biocatalyzed reactions and the use of DNA-functionalized magnetic nanoparticles. Digital XOR and NAND logic gates and copying (fanout) are designed using the same components., Comment: 14 pages in PDF

We outline different approaches to define and quantify decoherence. We argue that a measure based on a properly defined norm of deviation of the density matrix is appropriate for quantifying decoherence in quantum registers. For a semiconductor double quantum dot qubit, evaluation of this measure is reviewed. For a general class of decoherence processes, including those occurring in semiconductor qubits, we argue that this measure is additive: It scales linearly with the number of qubits., Comment: Revised version, 26 pages, in LaTeX, 3 EPS figures

We will summarize and consider several examples of applications of semiclassical approaches used in semiconductor spintronic device modeling. These include drift-diffusion models, kinetic transport equations and Monte Carlo simulation schemes.

The authors summarise semiclassical modelling methods, including drift-diffusion, kinetic transport equation and Monte Carlo simulation approaches, utilised in studies of spin dynamics and transport in semiconductor structures. As a review of the work by the authors' group, several examples of applications of these modelling techniques are presented. © IEE, 2005.

A method for Monte Carlo simulation of 2D spin-polarized electron transport in III-V semiconductor heterojunction (FETs) is presented. In the simulation, the dynamics of the electrons in coordinate and momentum space is treated semiclassically. The density matrix description of the spin is incorporated in the Monte Carlo method to account for the spin polarization dynamics. The spin-orbit interaction in the spin FET leads to both coherent evolution and dephasing of the electron spin polarization. Spin-independent scattering mechanisms, including optical phonons, acoustic phonons and ionized impurities, are implemented in the simulation. The electric field is determined self-consistently from the charge distribution resulting from the electron motion. Description of the Monte Carlo scheme is given and simulation results are reported for temperatures in the range 77-300K. © 2004 IMACS. Published by Elsevier B.V. All rights reserved.

Monte Carlo simulations are performed to study the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells. The density matrix description of the spin polarization is incorporated in the simulation algorithm. The spin-orbit interaction terms generate coherent evolution of the electron spin polarization and also cause dephasing. The spatial motion of the electrons is treated semiclassically. Three different scattering mechanisms - optical phonons, acoustic phonons and ionized impurities - are considered. The electric field is calculated self-consistently from the charge distribution. The Monte Carlo scheme is described, and simulation results are reported for temperatures in the range 77-300 K. © Springer-Verlag Berlin Heidelberg 2003.

Monte Carlo simulations are performed to study the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells. The density matrix description of the spin polarization is incorporated in the simulation algorithm. The spin-orbit interaction terms generate coherent evolution of the electron spin polarization and also cause dephasing. The spatial motion of the electrons is treated semiclassically. Three different scattering mechanisms - optical phonons, acoustic phonons and ionized impurities - are considered. The electric field is calculated self-consistently from the charge distribution. The Monte Carlo scheme is described, and simulation results are reported for temperatures in the range 77-300 K. © Springer-Verlag Berlin Heidelberg 2003.

© 2003 IEEE. The Monte Carlo approach is utilized to study spin-polarized electron transport in spintronic device structures. Evolution of the electron spin polarization vector is controlled by the spin-orbit interaction. Spin polarization properties, including the spin-dephasing length and orientation of the polarization vector, are investigated, for the applied voltage from 0.05 V to 0.25 V, and for temperatures ranging from 77 K to 300 K.

Monte Carlo simulations are performed to study the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells. The density matrix description of the spin polarization is incorporated in the simulation algorithm. The spin-orbit interaction terms generate coherent evolution of the electron spin polarization and also cause dephasing. The spatial motion of the electrons is treated semiclassically. Three different scattering mechanisms - optical phonons, acoustic phonons and ionized impurities - are considered. The electric field is calculated self-consistently from the charge distribution. The Monte Carlo scheme is described, and simulation results are reported for temperatures in the range 77-300 K. © Springer-Verlag Berlin Heidelberg 2003.

Monte Carlo simulations are performed to study the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells. The density matrix description of the spin polarization is incorporated in the simulation algorithm. The spin-orbit interaction terms generate coherent evolution of the electron spin polarization and also cause dephasing. The spatial motion of the electrons is treated semiclassically. Three different scattering mechanisms - optical phonons, acoustic phonons and ionized impurities - are considered. The electric field is calculated self-consistently from the charge distribution. The Monte Carlo scheme is described, and simulation results are reported for temperatures in the range 77-300 K. © Springer-Verlag Berlin Heidelberg 2003.

The study of the in-plane transport of spin-polarized electrons in III-V semiconductor quantum wells was presented in the article. The Monte Carlo simulations were performed for temperatures in the range 77-330 K. The results for dynamics of the spin polarization in a single quantum well at several temperatures and intermediate, ∼2-4 kV/cm, electric fields, were reported.

We study the low-temperature dynamics of a shallow donor, e.g., 31P, impurity electron spin in silicon, interacting with the bath of nuclear spins of the 29Si isotope. For small applied magnetic fields, the electron spin relaxation is controlled by the steady-state distribution of the nuclear spins. We calculate the relaxation times T1 and T2 as functions of the external magnetic field and conclude that nuclear spins play an important role in the donor electron spin decoherence in Si:P at low magnetic fields.

We study a general quantum system interacting with environment modeled by the bosonic heat bath of Caldeira and Leggett type. General interaction Hamiltonians are considered that commute with the system's Hamiltonian so that there is no energy exchange between the system and bath. We argue that this model provides an appropriate description of adiabatic quantum decoherence, i.e., loss of entanglement on time scales short compared to those of thermal relaxation processes associated with energy exchange with the bath. The interaction Hamiltonian is then proportional to a conserved "pointer observable." Calculation of the elements of the reduced density matrix of the system is carried out exactly, and time-dependence of decoherence is identified, similar to recent results for related models. Our key finding is that the decoherence process is controlled by spectral properties of the interaction rather than system's Hamiltonian., Comment: 29 pages in TeX

The mathematical formalism of quantum mechanics has been successfully employed in the last years to model situations in which the use of classical structures gives rise to problematical situations, and where typically quantum effects, such as 'contextuality' and 'entanglement', have been recognized. This 'Quantum Interaction Approach' is briefly reviewed in this paper focusing, in particular, on the quantum models that have been elaborated to describe how concepts combine in cognitive science, and on the ensuing identification of a quantum structure in human thought. We point out that these results provide interesting insights toward the development of a unified theory for meaning and knowledge formalization and representation. Then, we analyze the technological aspects and implications of our approach, and a particular attention is devoted to the connections with symbolic artificial intelligence, quantum computation and robotics., 10 pages