46 research outputs found
Coarse-Grained Picture for Controlling Quantum Chaos
We propose a coarse-grained picture to analyze control problems for quantum
chaos systems. Using optimal control theory, we first show that almost perfect
control is achieved for random matrix systems and a quantum kicked rotor.
Second, under the assumption that the controlled dynamics is well described by
a Rabi-type oscillaion between unperturbed states, we derive an analytic
expression for the optimal field. Finally we numerically confirm that the
analytic field can steer an initial state to a target state in random matrix
systems.Comment: REVTeX4 with graphicx package, 11 pages, 10 figures; replaced
fig.1(a) and 2(a
Analytic Approach for Controlling Realistic Quantum Chaotic Systems
An analytic approach for controlling quantum states, which was originally
applied to fully random matrix systems [T. Takami and H. Fujisaki, Phys. Rev. E
75, 036219 (2007)], is extended to deal with more realistic quantum systems
with a banded random matrix (BRM). The validity of the new analytic field is
confirmed by directly solving the Schroedinger equation with a BRM interaction.
We find a threshold of the width of the BRM for the quantum control to be
successful.Comment: 4 pages with 4 PostScript figures, to appear in the Proceedings of
ICCMSE 2007 in a section of Symposium 8 "Quantum Control and Light-Matter
Interactions: Recent Computational and Theoretical Results
Sound Generation by a Turbulent Flow in Musical Instruments - Multiphysics Simulation Approach -
Total computational costs of scientific simulations are analyzed between
direct numerical simulations (DNS) and multiphysics simulations (MPS) for sound
generation in musical instruments. In order to produce acoustic sound by a
turbulent flow in a simple recorder-like instrument, compressible fluid dynamic
calculations with a low Mach number are required around the edges and the
resonator of the instrument in DNS, while incompressible fluid dynamic
calculations coupled with dynamics of sound propagation based on the
Lighthill's acoustic analogy are used in MPS. These strategies are evaluated
not only from the viewpoint of computational performances but also from the
theoretical points of view as tools for scientific simulations of complicated
systems.Comment: 6 pages, 10 figure files, to appear in the proceedings of HPCAsia0
Theoretical Estimation of the Acoustic Energy Generation and Absorption Caused by Jet Oscillation
We investigate the energy transfer between the fluid field and acoustic field caused by a jet driven by an acoustic particle velocity field across it, which is the key to understanding the aerodynamic sound generation of flue instruments, such as the recorder, flute, and organ pipe. Howe’s energy corollary allows us to estimate the energy transfer between these two fields. For simplicity, we consider the situation such that a free jet is driven by a uniform acoustic particle velocity field across it. We improve the semi-empirical model of the oscillating jet, i.e., exponentially growing jet model, which has been studied in the field of musical acoustics, and introduce a polynomially growing jet model so as to apply Howe’s formula to it. It is found that the relative phase between the acoustic oscillation and jet oscillation, which changes with the distance from the flue exit, determines the quantity of the energy transfer between the two fields. The acoustic energy is mainly generated in the downstream area, but it is consumed in the upstream area near the flue exit in driving the jet. This theoretical examination well explains the numerical calculation of Howe’s formula for the two-dimensional flue instrument model in our previous work [Fluid Dyn. Res. 46, 061411 (2014) ] as well as the experimental result of Yoshikawa et al. [ J. Sound Vib. 331, 2558 (2012) ]
Open-architecture Implementation of Fragment Molecular Orbital Method for Peta-scale Computing
We present our perspective and goals on highperformance computing for
nanoscience in accordance with the global trend toward "peta-scale computing."
After reviewing our results obtained through the grid-enabled version of the
fragment molecular orbital method (FMO) on the grid testbed by the Japanese
Grid Project, National Research Grid Initiative (NAREGI), we show that FMO is
one of the best candidates for peta-scale applications by predicting its
effective performance in peta-scale computers. Finally, we introduce our new
project constructing a peta-scale application in an open-architecture
implementation of FMO in order to realize both goals of highperformance in
peta-scale computers and extendibility to multiphysics simulations.Comment: 6 pages, 9 figures, proceedings of the 2nd IEEE/ACM international
workshop on high performance computing for nano-science and technology
(HPCNano06
Multi-physics Extension of OpenFMO Framework
OpenFMO framework, an open-source software (OSS) platform for Fragment
Molecular Orbital (FMO) method, is extended to multi-physics simulations (MPS).
After reviewing the several FMO implementations on distributed computer
environments, the subsequent development planning corresponding to MPS is
presented. It is discussed which should be selected as a scientific software,
lightweight and reconfigurable form or large and self-contained form.Comment: 4 pages with 11 figure files, to appear in the Proceedings of ICCMSE
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