14,570 research outputs found
Quantum-mechanical machinery for rational decision-making in classical guessing game
In quantum game theory, one of the most intriguing and important questions
is, "Is it possible to get quantum advantages without any modification of the
classical game?" The answer to this question so far has largely been negative.
So far, it has usually been thought that a change of the classical game setting
appears to be unavoidable for getting the quantum advantages. However, we give
an affirmative answer here, focusing on the decision-making process (we call
'reasoning') to generate the best strategy, which may occur internally, e.g.,
in the player's brain. To show this, we consider a classical guessing game. We
then define a one-player reasoning problem in the context of the
decision-making theory, where the machinery processes are designed to simulate
classical and quantum reasoning. In such settings, we present a scenario where
a rational player is able to make better use of his/her weak preferences due to
quantum reasoning, without any altering or resetting of the classically defined
game. We also argue in further analysis that the quantum reasoning may make the
player fail, and even make the situation worse, due to any inappropriate
preferences.Comment: 9 pages, 10 figures, The scenario is more improve
Density Power Spectrum of Compressible Hydrodynamic Turbulent Flows
Turbulent flows are ubiquitous in astrophysical environments, and
understanding density structures and their statistics in turbulent media is of
great importance in astrophysics. In this paper, we study the density power
spectra, , of transonic and supersonic turbulent flows through one
and three-dimensional simulations of driven, isothermal hydrodynamic turbulence
with root-mean-square Mach number in the range of 1 \la M_{\rm rms} \la 10.
From one-dimensional experiments we find that the slope of the density power
spectra becomes gradually shallower as the rms Mach number increases. It is
because the density distribution transforms from the profile with {\it
discontinuities} having for to
the profile with {\it peaks} having for . We also find that the same trend is carried to three-dimension; that is,
the density power spectrum flattens as the Mach number increases. But the
density power spectrum of the flow with has the Kolmogorov
slope. The flattening is the consequence of the dominant density structures of
{\it filaments} and {\it sheets}. Observations have claimed different slopes of
density power spectra for electron density and cold H I gas in the interstellar
medium. We argue that while the Kolmogorov spectrum for electron density
reflects the {\it transonic} turbulence of in the warm
ionized medium, the shallower spectrum of cold H I gas reflects the {\it
supersonic} turbulence of a few in the cold neutral medium.Comment: To appear in ApJ Lett. Pdf file with full resolution figures can be
downloaded from http://canopus.cnu.ac.kr/ryu/kimryu.pd
Time-reversal symmetric hierarchy of fractional incompressible liquids
We provide an effective description of fractional topological insulators that
include the fractional quantum spin Hall effect by considering the
time-reversal symmetric pendant to the topological quantum field theories that
encode the Abelian fractional quantum Hall liquids. We explain the hierarchical
construction of such a theory and establish for it a bulk-edge correspondence
by deriving the equivalent edge theory for chiral bosonic fields. Further, we
compute the Fermi-Bose correlation functions of the edge theory and provide
representative ground state wave functions for systems described by the bulk
theory.Comment: 14 page
Minimax optimization of entanglement witness operator for the quantification of three-qubit mixed-state entanglement
We develop a numerical approach for quantifying entanglement in mixed quantum
states by convex-roof entanglement measures, based on the optimal entanglement
witness operator and the minimax optimization method. Our approach is
applicable to general entanglement measures and states and is an efficient
alternative to the conventional approach based on the optimal pure-state
decomposition. Compared with the conventional one, it has two important merits:
(i) that the global optimality of the solution is quantitatively verifiable,
and (ii) that the optimization is considerably simplified by exploiting the
common symmetry of the target state and measure. To demonstrate the merits, we
quantify Greenberger-Horne-Zeilinger (GHZ) entanglement in a class of
three-qubit full-rank mixed states composed of the GHZ state, the W state, and
the white noise, the simplest mixtures of states with different genuine
multipartite entanglement, which have not been quantified before this work. We
discuss some general properties of the form of the optimal witness operator and
of the convex structure of mixed states, which are related to the symmetry and
the rank of states
Chemical beam epitaxial growth of InP and GaP by using tertiarybutylbis (dimethylamino) phosphine
Journal ArticleWe report the growth of indium phosphide (InP) by using a chemical beam epitaxy (CBE) technique with the group V source tertiarybutylbis (dimethylamino) phosphine (TBBDMAP). The photoluminescence spectra at 15 K showed that the intensity of a peak attributed to impurity recombination and the FWHM increased significantly when the cracker temperature exceed 545 ºC. This paper also reports the growth of GaP without precracking of the TBBDMAP source. While it was not possible to grow InP at 450 ºC, GaP was successfully grown at temperatures as low as 410 ºC, possibly due to the higher Ga-P bond strength which gives a longer TBBDMAP residence time on the surface before desorption. In this study, ethyldimethylindium (EDMIn) and triisopropylgallium (TlPGa) were used as the indium (In) and the gallium (Ga) sources, respectively
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Motor shaft vibrations may have a negative effect on ability to implement a stiff haptic wall
A one degree of freedom experimental test bed is used to
investigate the effects of elastic vibration in haptic devices. Strong angular vibration occurs at the motor rotor due to elastic deformation in the shaft. These vibrations occur due to large discontinuities in the virtual environment such as stiff contact which is common in haptics. Also looked at was the effect of these vibrations on stability and control. It was found that the vibrations may negatively affect the stability of the haptic device by introducing large measurement errors to the controller. The experiments investigated using different types of damping in controller feedback. Adding damping to the system whilst these elastic vibrations are present can successfully damp the system, but also tend to increase the magnitude of vibrations sometimes resulting in greater instability. Finally, a second non co-located encoder was used to try to eliminate measurement error from the system due to vibration. It was found that by simply placing the encoder closer to the link where the angle is being measured, error due to rotational flex in the shaft is eliminated. This yielded the greatest improvement in controller performance, nearly eliminating the presence of the vibrations and their effects
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