42,927 research outputs found
Simple Scheme for Efficient Linear Optics Quantum Gates
We describe the construction of a conditional quantum control-not (CNOT) gate
from linear optical elements following the program of Knill, Laflamme and
Milburn [Nature {\bf 409}, 46 (2001)]. We show that the basic operation of this
gate can be tested using current technology. We then simplify the scheme
significantly.Comment: Problems with PDF figures correcte
Independence Test for High Dimensional Random Vectors
This paper proposes a new mutual independence test for a large number of high dimensional random vectors. The test statistic is based on the characteristic function of the empirical spectral distribution of the sample covariance matrix. The asymptotic distributions of the test statistic under the null and local alternative hypotheses are established as dimensionality and the sample size of the data are comparable. We apply this test to examine multiple MA(1) and AR(1) models, panel data models with some spatial cross-sectional structures. In addition, in a flexible applied fashion, the proposed test can capture some dependent but uncorrelated structures, for example, nonlinear MA(1) models, multiple ARCH(1) models and vandermonde matrices. Simulation results are provided for detecting these dependent structures. An empirical study of dependence between closed stock prices of several companies from New York Stock Exchange (NYSE) demonstrates that the feature of cross-sectional dependence is popular in stock marketsIndependence test, cross-sectional dependence, empirical spectral distribution, characteristic function, Marcenko-Pastur Law
Patterned and Disordered Continuous Abelian Sandpile Model
We study critical properties of the continuous Abelian sandpile model with
anisotropies in toppling rules that produce ordered patterns on it. Also we
consider the continuous directed sandpile model perturbed by a weak quenched
randomness and study critical behavior of the model using perturbative
conformal field theory and show the model has a new random fixed point.Comment: 11 Pages, 6 figure
In-situ electrochemical fabrication of natural contacts on single nanowires
We report a template-based in-situ electrochemical method for fabricating
natural electric contacts on single nanowires using a pair of cross-patterned
electrodes. Such electric contacts are highly stable upon thermal cycling
between room temperature and milli-Kelvin temperatures. Direct imaging of the
single-nanowire contacts using scanning electron microscopy is also
demonstrated.Comment: 13 pages, 4 figure
Application of Information Theory in Nuclear Liquid Gas Phase Transition
Information entropy and Zipf's law in the field of information theory have
been used for studying the disassembly of nuclei in the framework of the
isospin dependent lattice gas model and molecular dynamical model. We found
that the information entropy in the event space is maximum at the phase
transition point and the mass of the cluster show exactly inversely to its
rank, i.e. Zipf's law appears. Both novel criteria are useful in searching the
nuclear liquid gas phase transition experimentally and theoretically.Comment: 5 pages, 5 figure
Analytic study of Gauss-Bonnet holographic superconductors in Born-Infeld electrodynamics
Using Sturm-Liouville (SL) eigenvalue problem, we investigate several
properties of holographic s-wave superconductors in Gauss-Bonnet gravity with
Born-Infeld electrodynamics in the probe limit. Our analytic scheme has been
found to be in good agreement with the numerical results. From our analysis it
is quite evident that the scalar hair formation at low temperatures is indeed
affected by both the Gauss-Bonnet as well as the Born-Infeld coupling
parameters. We also compute the critical exponent associated with the
condensation near the critical temperature. The value of the critical exponent
thus obtained indeed suggests a universal mean field behavior.Comment: 9 pages, Latex, minor modifications, To appear in JHE
Unified nonequilibrium dynamical theory for exchange bias and training effects
We investigate the exchange bias and training effects in the FM/AF
heterostructures using a unified Monte Carlo dynamical approach. This real
dynamical method has been proved reliable and effective in simulating dynamical
magnetization of nanoscale magnetic systems. The magnetization of the
uncompensated AF layer is still open after the first field cycling is finished.
Our simulated results show obvious shift of hysteresis loops (exchange bias)
and cycling dependence of exchange bias (training effect) when the temperature
is below 45 K. The exchange bias fields decrease with decreasing the cooling
rate or increasing the temperature and the number of the field cycling. With
the simulations, we show the exchange bias can be manipulated by controlling
the cooling rate, the distributive width of the anisotropy energy, or the
magnetic coupling constants. Essentially, these two effects can be explained on
the basis of the microscopical coexistence of both reversible and irreversible
moment reversals of the AF domains. Our simulated results are useful to really
understand the magnetization dynamics of such magnetic heterostructures. This
unified nonequilibrium dynamical method should be applicable to other exchange
bias systems.Comment: Chin. Phys. B, in pres
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