621 research outputs found
Entanglement dynamics of photon pairs emitted from quantum dot
We present a model to derive the state of the photon pairs generated by the
biexciton cascade decay of a self-assembled quantum dot, which agrees well with
the experimental result. Furthermore we calculate the concurrence and
entanglement sudden death is found in this system with temperature increasing,
which prevents quantum dot emits entangled photon pairs at a high temperature.
The relationship between the fine structure splitting and the sudden death
temperature is provided too
Phase Compensation Enhancement of Photon Pair Entanglement Generated from Biexciton Decays in Quantum Dots
Exciton fine-structure splittings within quantum dots introduce phase
differences between the two biexciton decay paths that greatly reduce the
entanglement of photon pairs generated via biexciton recombination. We analyze
this problem in the frequency domain and propose a practicable method to
compensate the phase difference by inserting a spatial light modulator, which
substantially improves the entanglement of the photon pairs without any loss.Comment: 4 pages, 3 figure
Device modeling of superconductor transition edge sensors based on the two-fluid theory
In order to support the design and study of sophisticated large scale
transition edge sensor (TES) circuits, we use basic SPICE elements to develop
device models for TESs based on the superfluid-normal fluid theory. In contrast
to previous studies, our device model is not limited to small signal
simulation, and it relies only on device parameters that have clear physical
meaning and can be easily measured. We integrate the device models in design
kits based on powerful EDA tools such as CADENCE and OrCAD, and use them for
versatile simulations of TES circuits. Comparing our simulation results with
published experimental data, we find good agreement which suggests that device
models based on the two-fluid theory can be used to predict the behavior of TES
circuits reliably and hence they are valuable for assisting the design of
sophisticated TES circuits.Comment: 10pages,11figures. Accepted to IEEE Trans. Appl. Supercon
Peripheral Leukocytapheresis Attenuates Acute Lung Injury Induced by Lipopolysaccharide In Vivo
The mortality of acute lung injury and acute respiratory distress syndrome (ALI/ARDS) remains high and efforts for prevention and treatments have shown little improvement over the past decades. The present study investigated the efficacy and mechanism of leukocytapheresis (LCAP) to partially eliminate peripheral neutrophils and attenuate lipopolysaccharide (LPS)-induced lung injury in dogs. A total of 24 healthy male mongrel dogs were enrolled and randomly divided into LPS, LCAP and LCAP-sham groups. All animals were injected with LPS to induce endotoxemia. The serum levels of leucocytes, neutrophil elastase, arterial blood gas, nuclear factor-kappa B (NF-κB) subunit p65 in lung tissues were measured. The histopathology and parenchyma apoptosis of lung tissues were examined. We found that 7, 3, and 7 animals in the LPS, LCAP, and sham-LCAP groups, respectively, developed ALI 36 h after LPS infusion. The levels of NF-κB p65 in lung tissue, neutrophils and elastase in blood, decreased significantly following LCAP. LCAP also alleviated apoptosis, and NF-κB p65 in lung tissues. Collectively, our results show that partial removal of leucocytes from peripheral blood decreases elastase level in serum. This, in turn, attenuates lung injuries and may potentially decrease the incidence of ALI
Entrance channel dependence and isospin dependence of preequilibrium nucleon emission in intermediate energy heavy ion collisions
Using isospin dependent quantum molecular dynamical model, the studies of the
isospin effect on preequilibrium nucleon emission in heavy ion collisions under
different entrance channel conditions show that the ratio of preequilibrium
neutron number to proton number depends strongly on symmetry potential, beam
energy, and the ratio of neutron to proton of the colliding system, but weakly
on isospin dependent in-medium nucleon-nucleon cross sections, impact
parameter, Pauli potential, and momentum dependent interaction in the energy
region from 45MeV/u up to 150 MeV/u where the dynamics is dominated by
nucleon-nucleon collisions. In addition, the ratio of preequilibrium neutron
number to proton number for a neutron-rich colliding system is larger than the
initial value of the ratio of the colliding system, but the ratio for a
neutron-deficient system is less than the initial value
An Opacity-Free Method of Testing the Cosmic Distance Duality Relation Using Strongly Lensed Gravitational Wave Signals
The cosmic distance duality relation (CDDR), expressed as DL(z) = (1 +
z)2DA(z), plays an important role in modern cosmology. In this paper, we
propose a new method of testing CDDR using strongly lensed gravitational wave
(SLGW) signals. Under the geometric optics approximation, we calculate the
gravitational lens effects of two lens models, the point mass and singular
isothermal sphere. We use functions of {\eta}1(z) = 1 + {\eta}0z and {\eta}2(z)
= 1 + {\eta}0z=(1 + z) to parameterize the deviation of CDDR. By
reparameterizing the SLGW waveform with CDDR and the distance-redshift
relation, we include the deviation parameters {\eta}0 of CDDR as waveform
parameters. We evaluate the ability of this method by calculating the parameter
estimation of simulated SLGW signals from massive binary black holes. We apply
the Fisher information matrix and Markov Chain Monte Carlo methods to calculate
parameter estimation. We find that with only one SLGW signal, the measurement
precision of {\eta}0 can reach a considerable level of 0.5-1.3% for {\eta}1(z)
and 1.1-2.6% for {\eta}2(z), depending on the lens model and parameters.Comment: 15 pages, 7 figure
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