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Condensed Matter papers — page 18

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Ab initio structure solution by charge flipping
In this paper we present an extremely simple structure solution method termed charge flipping. It works ab initio on high resolution x-ray diffraction data in the manner of Fourier recycling. The…
Gabor Oszlanyi, Andras SutoAug 7, 2003
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Numerical study of hydrogenic effective mass theory for an impurity P donor in Si in the presence of an electric field and interfaces
In this paper we examine the effects of varying several experimental parameters in the Kane quantum computer architecture: A-gate voltage, the qubit depth below the silicon oxide barrier, and the…
L. M. Kettle, H. S. Goan, Sean C. Smith et al.Aug 7, 2003
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Optical detection of fractional particle number in an atomic Fermi-Dirac gas
We study theoretically a Fermi-Dirac atomic gas in a one-dimensional optical lattice coupled to a coherent electromagnetic field with a topologically nontrivial soliton phase profile. We argue that…
Juha Javanainen, Janne RuostekoskiAug 6, 2003
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Charge transport and phase transition in exciton rings
The macroscopic exciton rings observed in the photoluminescence (PL) patterns of excitons in coupled quantum wells (CQWs) are explained by a series of experiments and a theory based on the idea of…
L. V. Butov, L. S. Levitov, A. V. Mintsev et al.Aug 6, 2003
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Spin singlet formation in MgTi2O4: evidence of a helical dimerization pattern
The transition metal spinel MgTi2O4 undergoes a metal-insulator transition on cooling below TM-I = 260 K. A sharp reduction of the magnetic susceptibility below TM-I suggests the…
M. Schmidt, W. Ratcliff, P. G. Radaelli et al.Aug 6, 2003
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Crossover from Poisson to Wigner-Dyson Level Statistics in Spin Chains with Integrability Breaking
We study numerically the evolution of energy-level statistics as an integrability-breaking term is added to the XXZ Hamiltonian. For finite-length chains, physical properties exhibit a cross-over…
D. A. Rabson, B. N. Narozhny, A. J. MillisAug 5, 2003
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Photoelasticity of crystalline and amorphous silica from first principles
Based on density-functional perturbation theory we have computed from first principles the photoelastic tensor of few crystalline phases of silica at normal conditions and high pressure (quartz,…
D. Donadio, M. Bernasconi, F. TassoneAug 5, 2003
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Assortative model for social networks
In this paper we present a new version of a network growth model, generalized in order to describe the behavior of social networks. The case of study considered is the preprint archive at…
Michele Catanzaro, Guido Caldarelli, Luciano PietroneroAug 5, 2003
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Dynamical model and nonextensive statistical mechanics of a market index on large time windows
The shape and tails of partial distribution functions (PDF) for a financial signal, i.e. the S&P500 and the turbulent nature of the markets are linked through a model encompassing Tsallis…
Marcel Ausloos, Kristinka IvanovaAug 5, 2003
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Effects of Inhomogeneity on the Spectrum of the Mott-Insulator State
We investigate the existence of quantum quasi phase transitions for an ensemble of ultracold bosons in a one-dimensional optical lattice, performing exact diagonalizations of the Bose-Hubbard…
G. Pupillo, E. Tiesinga, C. J. WilliamsAug 4, 2003
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Diversity and Adaptation in Large Population Games
We consider a version of large population games whose players compete for resources using strategies with adaptable preferences. The system efficiency is measured by the variance of the decisions. In…
K. Y. Michael Wong, S. W. Lim, Peixun LuoAug 4, 2003
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A Second Supersymmetry in Thermo Field Dynamics
This article is an extension of the work done in partha by R. Parthasarathy and R. Sridhar. There they consider supersymmetry in an enlarged thermal system (in a thermo field dynamic…
Xerxes D. ArsiwallaAug 4, 2003
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Nonresonant holeburning in the Terahertz range: Brownian oscillator model
The response to the field sequence of nonresonant hole burning, a pump-wait-probe experiment originally designed to investigate slow relaxation in complex systems, is calculated for a model of…
Uli Häberle, Gregor DiezemannAug 4, 2003
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The stochastic Gross-Pitaevskii equation II
We provide a derivation of a more accurate version of the stochastic Gross-Pitaevskii equation, as introduced by Gardiner et al. (J. Phys. B 35,1555,(2002). The derivation does not rely on the…
C. W. Gardiner, M. J. DavisAug 4, 2003
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Antiresonance and interaction-induced localization in spin and qubit chains with defects
We study a spin chain with an anisotropic XXZ coupling in an external field. Such a chain models several proposed types of a quantum computer. The chain contains a defect with a different on-site…
M. I. Dykman, L. F. SantosAug 1, 2003
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Noise, coherent fluctuations, and the onset of order in an oscillated granular fluid
We study fluctuations in a vertically oscillated layer of grains below the critical acceleration for the onset of ordered standing waves. As onset is approached, transient disordered waves with a…
Daniel I. Goldman, J. B. Swift, Harry L. SwinneyAug 1, 2003
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Production of Long-Lived Ultracold Li2 Molecules from a Fermi gas
We create weakly-bound Li2 molecules from a degenerate two component Fermi gas by sweeping a magnetic field across a Feshbach resonance. The atom-molecule transfer efficiency can reach 85% and is…
J. Cubizolles, T. Bourdel, S. J. J. M. F. Kokkelmans et al.Aug 1, 2003
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Space-time engineering with LASETRON pulses
The LASETRON project (Phys. Rev. Lett, 88, (2002), p. 074801-1) offers the possibility of the investigation of electron-positron structure of the space-time. Following our results (From Quarks to…
M. Kozlowski, J. Marciak-KozlowskaAug 1, 2003
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Ground-state properties of artificial bosonic atoms, Bose interaction blockade and the single-atom pipette
We analyze the ground-state properties of an artificial atom made out of repulsive bosons attracted to a center for the case that all the interactions are short-ranged. Such bosonic atoms could be…
Eugene B. Kolomeisky, Joseph P. Straley, Ryan M. KalasJul 31, 2003
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Voronoi and Fractal Complex Networks and Their Characterization
Real complex networks are often characterized by spatial constraints such as the relative position and adjacency of nodes. The present work describes how Voronoi tessellations of the space where the…
Luciano da Fontoura CostaJul 31, 2003
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Complex lithium ion dynamics in simulated LiPO3 glass studied by means of multi-time correlation functions
Molecular dynamics simulations are performed to study the lithium jumps in LiPO3 glass. In particular, we calculate higher-order correlation functions that probe the positions of single lithium ions…
Michael VogelJul 30, 2003
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Dirac monopoles and dipoles in ferromagnetic spinor Bose-Einstein condensates
We investigate a radial spin hedgehog, analogous to the Dirac monopole, in an optically trapped atomic spin-1 Bose-Einstein condensate. By joining together a monopole-antimonopole pair, we may form a…
C. M. Savage, J. RuostekoskiJul 30, 2003
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Superfluidity of trapped dipolar Fermi gases
We derive the phase diagram for ultracold trapped dipolar Fermi gases. Below the critical value of the dipole-dipole interaction energy, the BCS transition into a superfluid phase ceases to exist.…
M. A. Baranov, L. Dobrek, M. LewensteinJul 28, 2003
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Geometry and Conductance of Al Wires Suspended between Semi-Infinite Crystalline Electrodes
We present a first-principles study of a coherent relationship between the optimized geometry and conductance of a three-aluminum-atom wire during its elongation process. Our simulation employs the…
Tomoya Ono, Kikuji HiroseJul 28, 2003
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First-principles study on field evaporation for silicon atom on Si(001) surface
The simulations of field-evaporation processes for silicon atoms on various Si(001) surfaces are implemented using the first-principles calculations based on the real-space finite-difference method.…
Tomoya Ono, Kikuji HiroseJul 28, 2003
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