35,767 research outputs found
Polynomial and rational solutions of holonomic systems
The aim of this paper is to give two new algorithms, which are elimination
free, to find polynomial and rational solutions for a given holonomic system
associated to a set of linear differential operators in the Weyl algebra D =
k where k is a subfield of the complex numbers.Comment: 20 page
Global dispersive solutions for the Gross-Pitaevskii equation in two and three dimensions
We study asymptotic behaviour at time infinity of solutions close to the
non-zero constant equilibrium for the Gross-Pitaevskii equation in two and
three spatial dimensions. We construct a class of global solutions with
prescribed dispersive asymptotic behavior, which is given in terms of the
linearized evolution
Strain modification in coherent Ge and SixGe1–x epitaxial films by ion-assisted molecular beam epitaxy
We have observed large changes in Ge and SixGe1–x layer strain during concurrent molecular beam epitaxial growth and low-energy bombardment. Layers are uniformly strained, coherent with the substrate, and contain no dislocations, suggesting that misfit strain is accommodated by free volume changes associated with injection of ion bombardment induced point defects. The dependence of layer strain on ion energy, ion-atom flux ratio, and temperature is consistent with the presence of a uniform dispersion of point defects at high concentration. Implications for distinguishing ion-surface interactions from ion-bulk interactions are discussed
How do Neutrinos Propagate ? - Wave-Packet Treatment of Neutrino Oscillation
The wave-packet treatment of neutrino oscillation developed previously is
extended to the case in which momentum distribution functions are taken to be a
Gaussian form with both central values and dispersions depending on the mass
eigenstates of the neutrinos. It is shown among other things that the velocity
of the neutrino wave packets does not in general agree with what one would
expect classically and that relativistic neutrinos emitted from pions
nevertheless do follow, to a good approximation, the classical trajectory.Comment: 13 page. No figure. Typeset using PTPTeX.st
Charge echo in a Cooper-pair box
A spin-echo-type technique is applied to an artificial two-level system that
utilizes charge degree of freedom in a small superconducting electrode.
Gate-voltage pulses are used to produce the necessary pulse sequence in order
to eliminate the inhomogeneity effect in the time-ensemble measurement and to
obtain refocused echo signals. Comparison of the decay time of the observed
echo signal with estimated decoherence time suggests that low-frequency
energy-level fluctuations due to the 1/f charge noise dominate the dephasing in
the system.Comment: 4 pages, 3 figure
Dynamical Properties of a Growing Surface on a Random Substrate
The dynamics of the discrete Gaussian model for the surface of a crystal
deposited on a disordered substrate is investigated by Monte Carlo simulations.
The mobility of the growing surface was studied as a function of a small
driving force and temperature . A continuous transition is found from
high-temperature phase characterized by linear response to a low-temperature
phase with nonlinear, temperature dependent response. In the simulated regime
of driving force the numerical results are in general agreement with recent
dynamic renormalization group predictions.Comment: 10 pages, latex, 3 figures, to appear in Phys. Rev. E (RC
Self-consistent determination of the perpendicular strain profile of implanted Si by analysis of x-ray rocking curves
Results of a determination of strain perpendicular to the surface and of the damage in (100) Si single crystals irradiated by 250-keV Ar+ ions at 77 K are presented. Double-crystal x-ray diffraction and dynamical x-ray diffraction theory are used. Trial strain and damage distributions were guided by transmission electron microscope observations and Monte Carlo simulation of ion energy deposition. The perpendicular strain and damage profiles, determined after sequentially removing thin layers of Ar+-implanted Si, were shown to be self-consistent, proving the uniqueness of the deconvolution. Agreement between calculated and experimental rocking curves is obtained with strain and damage distributions which closely follow the shape of the trim simulations from the maximum damage to the end of the ion range but fall off more rapidly than the simulation curve near the surface. Comparison of the trim simulation and the strain profile of Ar+-implanted Si reveals the importance of annealing during and after implantation and the role of complex defects in the final residual strain distribution
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