Search results for "Master"

Robust Adaptive H∞ Synchronization of Master-Slave Systems with Discrete and Distributed Time-Varying Delays and Nonlinear Perturbations

2011

Author's version of a chapter published in the book: Proceedings of the 18th IFAC World Congress 2011. Also available from the publisher at: http://dx.doi.org/10.3182/20110828-6-IT-1002.03116

Giant Quantum Oscillators from Rydberg Atoms: Atomic Coherent States and Their Squeezing from Rydberg Atoms

1989

This paper summarises work since about 1979 by all the authors indicated: RKB is given prominence only because he bears the responsibility for the present paper. All the work has proved relevant to Rydberg atoms. Here we lay particular stress on recent results for squeezing by Rydberg atoms.

Electrical fluctuations in monolayer-protected metal nanoclusters

2008

Abstract Monolayer-protected clusters (MPCs) are formed by a neutral or charged metallic core surrounded by an organic ligand monolayer. We estimate the electric potential fluctuations of a MPC in an electrolyte solution by using the equilibrium fluctuation–dissipation theorem and the non-linear Poisson–Boltzmann equation extended to account for ion penetration in the monolayer. Significant fluctuations are predicted because the MPC capacitance is small (approximately 1 aF). We study also the non-equilibrium case of a MPC sandwiched between two electrodes and estimate the current noise considering the nanocluster as a single electron transistor and using a theoretical approach based on the …

Adatom Island Diffusion on Metal Fcc(100) Surfaces

2001

We study the energetics and atomic mechanisms of diffusion of adatom islands on fcc(100) metal surfaces. For small islands, we perform detailed microscopic calculations using semi-empirical embedded-atom model and glue potentials in the case of Cu and Al, respectively. Combining systematic saddle-point search methods and molecular statics simulations allows us to find all the relevant transition paths for island motion. In particular, we demonstrate that there are novel many-body mechanisms such as internal row shearing which can, in some cases, control the island dynamics. Next, we show how using the master equation formalism, diffusion coefficients for small islands up to about five atoms…

A new mathematical tool for an exact treatment of open quantum system dynamics

2005

A new method to obtain an operatorial exact solution of a wide class of Markovian master equations is presented. Its key point is the existence of a constant of motion partitioning the Hilbert space into finite-dimensional subspaces. The consequent possibility of representing the reduced density operator as a block diagonal matrix is shown. Each “block operator” evolves under the action of a non-unitary operator explicitly derived. Our mathematical approach is illustrated applying it to simple physical systems.

The Master Equation

2009

Fluctuation-dissipation relations for Markov processes.

2005

The fluctuation-dissipation relation is calculated for stochastic models obeying a master equation with continuous time. In the general case of a nonstationary process, there appears to be no simple relation between the response and the correlation. Also, if one considers stationary processes, the linear response cannot be expressed via time-derivatives of the correlation function alone. In this case, an additional function, which has rarely been discussed previously, is required. This so-called asymmetry depends on the two times also relevant for the response and the correlation and it vanishes under equilibrium conditions. The asymmetry can be expressed in terms of the propagators and the…

Effective hamiltonian approach to the non-Markovian dynamics in a spin-bath

2010

We investigate the dynamics of a central spin that is coupled to a bath of spins through a non-uniform distribution of coupling constants. Simple analytical arguments based on master equation techniques as well as numerical simulations of the full von Neumann equation of the total system show that the short-time damping and decoherence behaviour of the central spin can be modelled accurately through an effective Hamiltonian involving a single effective coupling constant. The reduced short-time dynamics of the central spin is thus reproduced by an analytically solvable effective Hamiltonian model.

Non-Markovian master equation for the XX central spin model

2008

The non-Markovian correlated projection operator technique is applied to the model of a central spin coupled to a spin bath through non uniform XX Heisenberg coupling. The second order results of the Nakajima-Zwanzig and of the time-convolutionless methods are compared with the exact solution considering a fully polarized initial bath state.

Verso le città del mondo

2010

The “Città del mondo” significantly characterized the first series of «In Architecture», best representing the pioneering spirit of the journal and the architectural and cultural research of its authors. The comparison between local realities, generally small towns of the Sicilian hinterland and cities of different sizes and latitudes, already explicitly in the intentions of the method the reference to the universality of experience, making the intertwining of horizons that it allows civil progress and the growth of creative abilities.