58,784 research outputs found
Generating EPR beams in a cavity optomechanical system
We propose a scheme to produce continuous variable entanglement between
phase-quadrature amplitudes of two light modes in an optomechanical system. For
proper driving power and detuning, the entanglement is insensitive with bath
temperature and of mechanical oscillator. Under realistic experimental
conditions, we find that the entanglement could be very large even at room
temperature.Comment: 4.1 pages, 4 figures, comments are welcome; to appear in PRA,
published version with corrections of typo
Pair Production of MSSM Higgs Bosons in the Non-decoupling Region at the LHC
We consider the Higgs boson signals from pair production at the LHC within
the framework of the MSSM in the non-decoupling (low-m_A) region. In light of
the recent observation of a SM-like Higgs boson, we argue that the exploration
for Higgs pair production at the LHC is a crucial next step to probe the MSSM
Higgs sector. We emphasize that the production of H^\pm A^0 and H^{+}H^{-}
depends only on the electroweak gauge couplings while all the leading Higgs
production channels via gluon fusion, vector-boson fusion, and Higgsstrahlung
depend on additional free Higgs sector parameters. In the non-decoupling
region, the five MSSM Higgs bosons are all relatively light and pair production
signals may be accessible. We find that at the 8 TeV LHC, a 5\sigma signal for
H^\pm A^0, H^\pm h^0 -> \tau^{\pm}\nu b\bar b and H^{+}H^{-} -> \tau^{+}\nu
\tau^{-}\nu are achievable with an integrated luminosity of 7 (11) fb^{-1} and
24 (48) fb^{-1}, respectively for m_A=95 (130) GeV. At the 14 TeV LHC, a
5\sigma signal for these two channels would require as little as 4 (7) fb^{-1}
and 10 (19) fb^{-1}, respectively.Comment: 20 pages, 8 figures and 3 tables. Version to appear in PR
Birthrates and delay times of Type Ia supernovae
Type Ia supernovae (SNe Ia) play an important role in diverse areas of
astrophysics, from the chemical evolution of galaxies to observational
cosmology. However, the nature of the progenitors of SNe Ia is still unclear.
In this paper, according to a detailed binary population synthesis study, we
obtained SN Ia birthrates and delay times from different progenitor models, and
compared them with observations. We find that the Galactic SN Ia birthrate from
the double-degenerate (DD) model is close to those inferred from observations,
while the birthrate from the single-degenerate (SD) model accounts for only
about 1/2-2/3 of the observations. If a single starburst is assumed, the
distribution of the delay times of SNe Ia from the SD model is a weak
bimodality, where the WD + He channel contributes to the SNe Ia with delay
times shorter than 100Myr, and the WD + MS and WD + RG channels to those with
age longer than 1Gyr.Comment: 11 pages, 2 figures, accepted by Science in China Series G (Dec.30,
2009
Momentum Distribution of Near-Zero-Energy Photoelectrons in the Strong-Field Tunneling Ionization in the Long Wavelength Limit
We investigate the ionization dynamics of Argon atoms irradiated by an
ultrashort intense laser of a wavelength up to 3100 nm, addressing the momentum
distribution of the photoelectrons with near-zero-energy. We find a surprising
accumulation in the momentum distribution corresponding to meV energy and a
\textquotedblleft V"-like structure at the slightly larger transverse momenta.
Semiclassical simulations indicate the crucial role of the Coulomb attraction
between the escaping electron and the remaining ion at extremely large
distance. Tracing back classical trajectories, we find the tunneling electrons
born in a certain window of the field phase and transverse velocity are
responsible for the striking accumulation. Our theoretical results are
consistent with recent meV-resolved high-precision measurements.Comment: 5 pages, 4 figure
Magnetic Vortex Core Dynamics in a Ferromagnetic Dot
We report direct imaging by means of x-ray photoemission electron microscopy
of the dynamics of magnetic vortices confined in micron-size circular Permalloy
dots that are 30 nm thick. The vortex core positions oscillate on a 10-ns
timescale in a self-induced magnetostatic potential well after the in-plane
magnetic field is turned off. The measured oscillation frequencies as a
function of the aspect ratio (thickness/radius) of the dots are in agreement
with theoretical calculations presented for the same geometry.Comment: 18 pages including 4 figure
A Pseudo Random Numbers Generator Based on Chaotic Iterations. Application to Watermarking
In this paper, a new chaotic pseudo-random number generator (PRNG) is
proposed. It combines the well-known ISAAC and XORshift generators with chaotic
iterations. This PRNG possesses important properties of topological chaos and
can successfully pass NIST and TestU01 batteries of tests. This makes our
generator suitable for information security applications like cryptography. As
an illustrative example, an application in the field of watermarking is
presented.Comment: 11 pages, 7 figures, In WISM 2010, Int. Conf. on Web Information
Systems and Mining, volume 6318 of LNCS, Sanya, China, pages 202--211,
October 201
Convergence Rate of Sample Mean for -Mixing Random Variables with Heavy-Tailed Distributions
This article studies the convergence rate of the sample mean for
-mixing dependent random variables with finite means and infinite
variances. Dividing the sample mean into sum of the average of the main parts
and the average of the tailed parts, we not only obtain the convergence rate of
the sample mean but also prove that the convergence rate of the average of the
main parts is faster than that of the average of the tailed parts
Nonclassical photon pairs generated from a room-temperature atomic ensemble
We report experimental generation of non-classically correlated photon pairs
from collective emission in a room-temperature atomic vapor cell. The
nonclassical feature of the emission is demonstrated by observing a violation
of the Cauchy-Schwarz inequality. Each pair of correlated photons are separated
by a controllable time delay up to 2 microseconds. This experiment demonstrates
an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme
for scalable long-distance quantum communication.Comment: 4 pages, 2 figure
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