12,080 research outputs found
Voltage-Current curves for small Josephson junction arrays
We compute the current voltage characteristic of a chain of identical
Josephson circuits characterized by a large ratio of Josephson to charging
energy that are envisioned as the implementation of topologically protected
qubits. We show that in the limit of small coupling to the environment it
exhibits a non-monotonous behavior with a maximum voltage followed by a
parametrically large region where . We argue that its
experimental measurement provides a direct probe of the amplitude of the
quantum transitions in constituting Josephson circuits and thus allows their
full characterization.Comment: 12 pages, 4 figure
Abelian deterministic self organized criticality model: Complex dynamics of avalanche waves
The aim of this study is to investigate a wave dynamics and size scaling of
avalanches which were created by the mathematical model {[}J. \v{C}ern\'ak
Phys. Rev. E \textbf{65}, 046141 (2002)]. Numerical simulations were carried
out on a two dimensional lattice in which two constant thresholds
and were randomly distributed. A density
of sites with the threshold and threshold are
parameters of the model. I have determined autocorrelations of avalanche size
waves, Hurst exponents, avalanche structures and avalanche size moments for
several densities and thresholds . I found correlated avalanche
size waves and multifractal scaling of avalanche sizes not only for specific
conditions, densities , 1.0 and thresholds , in
which relaxation rules were precisely balanced, but also for more general
conditions, densities and thresholds $8\leq E_{c}^{II}\leq3 in
which relaxation rules were unbalanced. The results suggest that the hypothesis
of a precise relaxation balance could be a specific case of a more general
rule
Variational solution of the Gross-Neveu model at finite temperature in the large N limit
We use a nonperturbative variational method to investigate the phase
transition of the Gross-Neveu model. It is shown that the variational procedure
can be generalized to the finite temperature case. The large N result for the
phase transition is correctly reproduced.Comment: 12 p., 1 fig, this is the version which will appear in the Phys Lett
B, it differs from the previous one in what concerns the introduction and
conclusions (re written), several references have been adde
spectra in elementary cellular automata and fractal signals
We systematically compute the power spectra of the one-dimensional elementary
cellular automata introduced by Wolfram. On the one hand our analysis reveals
that one automaton displays spectra though considered as trivial, and on
the other hand that various automata classified as chaotic/complex display no
spectra. We model the results generalizing the recently investigated
Sierpinski signal to a class of fractal signals that are tailored to produce
spectra. From the widespread occurrence of (elementary) cellular
automata patterns in chemistry, physics and computer sciences, there are
various candidates to show spectra similar to our results.Comment: 4 pages (3 figs included
Matrix Product State description of the Halperin States
Many fractional quantum Hall states can be expressed as a correlator of a
given conformal field theory used to describe their edge physics. As a
consequence, these states admit an economical representation as an exact Matrix
Product States (MPS) that was extensively studied for the systems without any
spin or any other internal degrees of freedom. In that case, the correlators
are built from a single electronic operator, which is primary with respect to
the underlying conformal field theory. We generalize this construction to the
archetype of Abelian multicomponent fractional quantum Hall wavefunctions, the
Halperin states. These latest can be written as conformal blocks involving
multiple electronic operators and we explicitly derive their exact MPS
representation. In particular, we deal with the caveat of the full wavefunction
symmetry and show that any additional SU(2) symmetry is preserved by the
natural MPS truncation scheme provided by the conformal dimension. We use our
method to characterize the topological order of the Halperin states by
extracting the topological entanglement entropy. We also evaluate their bulk
correlation length which are compared to plasma analogy arguments.Comment: 23 pages, 16 figure
Stable fractal sums of pulses: the cylindrical case
A class of α-stable, 0\textlessα\textless2, processes is obtained as a sum of âup-and-downâ pulses determined by an appropriate Poisson random measure. Processes are H-self-affine (also frequently called âself-similarâ) with H\textless1/α and have stationary increments. Their two-dimensional dependence structure resembles that of the fractional Brownian motion (for H\textless1/2), but their sample paths are highly irregular (nowhere bounded with probability 1). Generalizations using different shapes of pulses are also discussed
Educational Motivation in Heritage Speakers of Spanish
This study examined the themes associated with the lack of motivation for school in middle school students, specifically among Heritage Speakers of Spanish. The researcher used two methods to examine student and parent attitudes and beliefs about school and education, as attitudes and beliefs are strongly linked to motivation. The researcher did face-to-face interviews of Mexican parents with direct questions about education and school, and asked middle school students of Mexican descent to read the first part of a short selection about a Mexican immigrant boy in school, then complete the story using their imagination. The researcher compiled the parents\u27 responses, and used content analysis to identify eight themes in the students \u27 narratives. Four findings emerged from the data: Mexican immigrant parents are perceived by their children as ineffective adults, parental expectations regarding school and the future are in conflict with student expectations, students have more extrinsic motivation (rewards) than intrinsic motivation (learning for itself), and students perceive many obstacles to school success
Cross correlation surveys with the Square Kilometre Array
By the time that the first phase of the Square Kilometre Array is deployed it
will be able to perform state of the art Large Scale Structure (LSS) as well as
Weak Gravitational Lensing (WGL) measurements of the distribution of matter in
the Universe. In this chapter we concentrate on the synergies that result from
cross-correlating these different SKA data products as well as external
correlation with the weak lensing measurements available from CMB missions. We
show that the Dark Energy figures of merit obtained individually from WGL/LSS
measurements and their independent combination is significantly increased when
their full cross-correlations are taken into account. This is due to the
increased knowledge of galaxy bias as a function of redshift as well as the
extra information from the different cosmological dependences of the
cross-correlations. We show that the cross-correlation between a spectroscopic
LSS sample and a weak lensing sample with photometric redshifts can calibrate
these same photometric redshifts, and their scatter, to high accuracy by
modelling them as nuisance parameters and fitting them simultaneously
cosmology. Finally we show that Modified Gravity parameters are greatly
constrained by this cross-correlations because weak lensing and redshift space
distortions (from the LSS survey) break strong degeneracies in common
parameterisations of modified gravity.Comment: 12 pages, 3 figures. This article is part of the 'Cosmology Chapter,
Advancing Astrophysics with the SKA (AASKA14) Conference, Giardini Naxos
(Italy), June 9th-13th 2014
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