39,610 research outputs found
Erratum : Squeezing and entanglement delay using slow light
An inconsistency was found in the equations used to calculate the variance of
the quadrature fluctuations of a field propagating through a medium
demonstrating electromagnetically induced transparency (EIT). The decoherence
term used in our original paper introduces inconsistency under weak probe
approximation. In this erratum we give the Bloch equations with the correct
dephasing terms. The conclusions of the original paper remain the same. Both
entanglement and squeezing can be delayed and preserved using EIT without
adding noise when the decoherence rate is small.Comment: 1 page, no figur
Random solids and random solidification: What can be learned by exploring systems obeying permanent random constraints?
In many interesting physical settings, such as the vulcanization of rubber,
the introduction of permanent random constraints between the constituents of a
homogeneous fluid can cause a phase transition to a random solid state. In this
random solid state, particles are permanently but randomly localized in space,
and a rigidity to shear deformations emerges. Owing to the permanence of the
random constraints, this phase transition is an equilibrium transition, which
confers on it a simplicity (at least relative to the conventional glass
transition) in the sense that it is amenable to established techniques of
equilibrium statistical mechanics. In this Paper I shall review recent
developments in the theory of random solidification for systems obeying
permanent random constraints, with the aim of bringing to the fore the
similarities and differences between such systems and those exhibiting the
conventional glass transition. I shall also report new results, obtained in
collaboration with Weiqun Peng, on equilibrium correlations and
susceptibilities that signal the approach of the random solidification
transition, discussing the physical interpretation and values of these
quantities both at the Gaussian level of approximation and, via a
renormalization-group approach, beyond.Comment: Paper presented at the "Unifying Concepts in Glass Physics" workshop,
International Centre for Theoretical Physics, Trieste, Italy (September
15-18, 1999
Automated Mixed Traffic Vehicle (AMTV) technology and safety study
Technology and safety related to the implementation of an Automated Mixed Traffic Vehicle (AMTV) system are discussed. System concepts and technology status were reviewed and areas where further development is needed are identified. Failure and hazard modes were also analyzed and methods for prevention were suggested. The results presented are intended as a guide for further efforts in AMTV system design and technology development for both near term and long term applications. The AMTV systems discussed include a low speed system, and a hybrid system consisting of low speed sections and high speed sections operating in a semi-guideway. The safety analysis identified hazards that may arise in a properly functioning AMTV system, as well as hardware failure modes. Safety related failure modes were emphasized. A risk assessment was performed in order to create a priority order and significant hazards and failure modes were summarized. Corrective measures were proposed for each hazard
Physical mechanism of anisotropic sensitivity in pentaerythritol tetranitrate from compressive-shear reaction dynamics simulations
We propose computational protocol (compressive shear reactive dynamics) utilizing the ReaxFF reactive force field to study chemical initiation under combined shear and compressive load. We apply it to predict the anisotropic initiation sensitivity observed experimentally for shocked pentaerythritol tetranitrate single crystals. For crystal directions known to be sensitive we find large stress overshoots and fast temperature increase that result in early bond-breaking processes whereas insensitive directions exhibit small stress overshoot, lower temperature increase, and little bond dissociation. These simulations confirm the model of steric hindrance to shear and capture the thermochemical processes dominating the phenomena of shear-induced chemical initiation
Goldstone fluctuations in the amorphous solid state
Goldstone modes in the amorphous solid state, resulting from the spontaneous
breaking of translational symmetry due to random localisation of particles, are
discussed. Starting from a microscopic model with quenched disorder, the broken
symmetry is identified to be that of relative translations of the replicas.
Goldstone excitations, corresponding to pure shear deformations, are
constructed from long wavelength distortions of the order parameter. The
elastic free energy is computed, and it is shown that Goldstone fluctuations
destroy localisation in two spatial dimensions, yielding a two-dimensional
amorphous solid state characterised by power-law correlations.Comment: 7 pages, 2 figure
Finite-sample frequency distributions originating from an equiprobability distribution
Given an equidistribution for probabilities p(i)=1/N, i=1..N. What is the
expected corresponding rank ordered frequency distribution f(i), i=1..N, if an
ensemble of M events is drawn?Comment: 4 pages, 4 figure
Effects of using different plasmonic metals in metal/dielectric/metal subwavelength waveguides on guided dispersion characteristics
The fundamental guided dispersion characteristics of guided light in a
subwavelength dielectric slit channel embedded by two different plasmonic
metals are investigated when varying the gap width. As a result, an overall and
salient picture of the guided dispersion characteristics is obtained over a
wide spectrum range below and above the plasma frequencies of the two different
plasmonic metals, which is important preliminary information for analyzing this
type of subwavelength waveguide. In particular, the effects of using two
different metals on the guided mode dispersions are emphasized in comparison
with the effects of using the same plasmonic metal cladding.Comment: 13 pages, 3 figures, typos corrected, reference added, text modifie
Statistical Properties of Share Volume Traded in Financial Markets
We quantitatively investigate the ideas behind the often-expressed adage `it
takes volume to move stock prices', and study the statistical properties of the
number of shares traded for a given stock in a fixed time
interval . We analyze transaction data for the largest 1000 stocks
for the two-year period 1994-95, using a database that records every
transaction for all securities in three major US stock markets. We find that
the distribution displays a power-law decay, and that the
time correlations in display long-range persistence. Further, we
investigate the relation between and the number of transactions
in a time interval , and find that the long-range
correlations in are largely due to those of . Our
results are consistent with the interpretation that the large equal-time
correlation previously found between and the absolute value of
price change (related to volatility) are largely due to
.Comment: 4 pages, two-column format, four figure
On the relevance of percolation theory to the vulcanization transition
The relationship between vulcanization and percolation is explored from the
perspective of renormalized local field theory. We show rigorously that the
vulcanization and percolation correlation functions are governed by the same
Gell--Mann-Low renormalization group equation. Hence, all scaling aspects of
the vulcanization transition are reigned by the critical exponents of the
percolation universality class.Comment: 9 pages, 2 figure
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