33,493 research outputs found
Optoelectromechanical transducer: reversible conversion between microwave and optical photons
Quantum states encoded in microwave photons or qubits can be effectively
manipulated, whereas optical photons can be coherently transferred via optical
fibre and waveguide. The reversible conversion of quantum states between
microwave and optical photons will hence enable the distribution of quantum
information over long distance and significantly improve the scalability of
hybrid quantum systems. Owning to technological advances, mechanical resonators
couple to quantum devices in distinctly different spectral range with tunable
coupling, and can serve as a powerful interface to connect those devices. In
this review, we summarize recent theory and experimental progress in the
coherent conversion between microwave and optical fields via
optoelectromechanical transducers. The challenges and perspectives in achieving
single-photon-level quantum state conversion will also be discussed.Comment: Review article, to appear in Annalen der Physik; 7 figure
The Crucial Constants in the Exponential-type Error Estimates for Multiquadric Interpolations
It's well known that in the high-level error bound for multiquadric
interpolation there is a crucial constant lambda lying between 0 and 1 which
connot be calculated or even approximated. The purpose of this paper is to
answer this question.Comment: 14 pages, approximation theory, radial basis functio
The Shape Parameter in the Shifted Surface Spline
There is a constant c contained in the famous radial basis function shifted
surface spline. It's called shape parameter. RBF people only know that this
constant is very influential, while its optimal choice is unknown. This paper
presents criteria of its optimal choice.Comment: 10 page
An extension of gas-kinetic BGK Navier-Stokes scheme to multidimensional astrophysical magnetohydrodynamics
The multidimensional gas-kinetic scheme for the Navier-Stokes equations under
gravitational fields [J. Comput. Phys. 226 (2007) 2003-2027] is extended to
resistive magnetic flows. The non-magnetic part of the magnetohydrodynamics
equations is calculated by a BGK solver modified due to magnetic field. The
magnetic part is treated by the flux splitting method based gas-kinetic theory
[J. Comput. Phys. 153 (1999) 334-352 ], using a particle distribution function
constructed in the BGK solver. To include Lorentz force effects into gas
evolution stage is very important to improve the accuracy of the scheme. For
some multidimensional problems, the deviations tangential to the cell interface
from equilibrium distribution are essential to keep the scheme robust and
accurate. Besides implementation of a TVD time discretization scheme, enhancing
the dynamic dissipation a little bit is a simply and efficient way to stabilize
the calculation. One-dimensional and two-dimensional shock waves tests are
calculated to validate this new scheme. A three-dimensional turbulent
magneto-convection simulation is used to show the applicability of current
scheme to complicated astrophysical flows.Comment: 24 pages, 13 figures. submitted to JC
The high-level error bound for shifted surface spline interpolation
Radial function interpolation of scattered data is a frequently used method
for multivariate data fitting. One of the most frequently used radial functions
is called shifted surface spline, introduced by Dyn, Levin and Rippa in
\cite{Dy1} for . Then it's extended to for . Many
articles have studied its properties, as can be seen in
\cite{Bu,Du,Dy2,Po,Ri,Yo1,Yo2,Yo3,Yo4}. When dealing with this function, the
most commonly used error bounds are the one raised by Wu and Schaback in
\cite{WS}, and the one raised by Madych and Nelson in \cite{MN2}. Both are
as , where is a positive integer and is the
fill-distance. In this paper we present an improved error bound which is
as , where is a constant which can be
accurately calculated.Comment: 14 pages, radial basis functions, approximation theory. arXiv admin
note: text overlap with arXiv:math/060115
The Mystery of the Shape Parameter II
In this paper we present criteria for the choice of the shape parameter c
contained in the famous radial function multiquadric. It may be of interest to
RBF people and all people using radial basis functions to do approximation.Comment: 15 figure
The Mystery of the Shape Parameter IV
In this paper we present a set of criteria for the choice of the shape
parameter c contained in multiquadrics.Comment: 12 pages, 15 figure
A Smooth and Compactly Supported Radial Function
In the field of radial basis functions mathematicians have been endeavouring
to find infinitely differentiable and compactly supported radial functions.
This kind of functions are extremely important for some reasons. First, its
computational properties will be very good since it's compactly supported.
Second, its error bound will converge very fast since it's infinitely
differentiable. However there is hitherto no such functions which can be
expressed in a simple form. This is a famous question. The purpose of this
paper is to answer this question.Comment: 4 pages, radial basis functions, approximation theor
On the High-Level Error Bound for Gaussian Interpolation
It's well-known that there is a very powerful error bound for Gaussians put
forward by Madych and Nelson in 1992. It's of the form where are constants,
is the Gaussian function, is the interpolating function, and d is called
fill distance which, roughly speaking, measures the spacing of the points at
which interpolation occurs. This error bound gets small very fast as .
The constants and are very sensitive. A slight change of them will
result in a huge change of the error bound. The number can be calculated as
shown in [9]. However, cannot be calculated, or even approximated. This is
a famous question in the theory of radial basis functions. The purpose of this
paper is to answer this question.Comment: approximation theory,radial basis function
Solving Poisson equations by the MN-curve approach
In this paper we apply the newly born choice theory of the shape parameters
contained in the smooth radial basis functions to solve Poisson equations. Some
people complain that Luh's choice theory, based on harmonic analysis, is
mathematically complicated and applies only to function interpolations. Here we
aim at presenting an easily accessible approach to solving differential
equations with the choice theory which proves to be successful, not only by its
easy accessibility, but also by its striking accuracy and efficiency.Comment: 9 pages, 11 figure
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