840 research outputs found
Bell Inequalities Classifying Bi-separable Three-qubit States
We present a set of Bell inequalities that gives rise to a finer
classification of the entanglement for tripartite systems. These inequalities
distinguish three possible bi-separable entanglements for three-qubit states.
The three Bell operators we employed constitute an external sphere of the
separable cube.Comment: 8 page
SU(2)-in-SU(1,1) Nested Interferometer for Highly Sensitive, Loss-Tolerant Quantum Metrology
We present experimental and theoretical results on a new interferometer
topology that nests a SU(2) interferometer, e.g., a Mach-Zehnder or Michelson
interferometer, inside a SU(1,1) interferometer, i.e., a Mach-Zehnder
interferometer with parametric amplifiers in place of beam splitters. This
SU(2)-in-SU(1,1) nested interferometer (SISNI) simultaneously achieves high
signal-to-noise ratio (SNR), sensitivity beyond the standard quantum limit
(SQL) and tolerance to photon losses external to the interferometer, e.g., in
detectors. We implement a SISNI using parametric amplification by four-wave
mixing (FWM) in Rb vapor and a laser-fed Mach-Zehnder SU(2) interferometer. We
observe path-length sensitivity with SNR 2.2 dB beyond the SQL at power levels
(and thus SNR) 2 orders of magnitude beyond those of previous loss-tolerant
interferometers. We find experimentally the optimal FWM gains and find
agreement with a minimal quantum noise model for the FWM process. The results
suggest ways to boost the in-practice sensitivity of high-power
interferometers, e.g., gravitational wave interferometers, and may enable
high-sensitivity, quantum-enhanced interferometry at wavelengths for which
efficient detectors are not available.Comment: 6 pages + 4 of supplemental material, 5 figure
Isospin Effect on the Process of Multifragmentation and Dissipation at Intermediate Energy Heavy Ion Collisions
In the simulation of intermediate energy heavy ion collisions by using the
isospin dependent quantum molecular dynamics, the isospin effect on the process
of multifragmentation and dissipation has been studied. It is found that the
multiplicity of intermediate mass fragments for the neutron-poor
colliding system is always larger than that for the neutron-rich system, while
the quadrupole of single particle momentum distribution for the
neutron-poor colliding system is smaller than that of the neutron-rich system
for all projectile-target combinations studied at the beam energies from about
50MeV/nucleon to 150MeV/nucleon. Since depends strongly on isospin
dependence of in-medium nucleon-nucleon cross section and weakly on symmetry
potential at the above beam energies, it may serve as a good probe to extract
the information on the in-medium nucleon-nucleon cross section. The correlation
between the multiplicity of intermediate mass fragments and the total
numer of charged particles has the behavior similar to , which
can be used as a complementary probe to the in-medium nucleon-nucleon cross
section.Comment: 18 pages, 9 figure
Optimized ultrasound-assisted extraction of phenolic compounds from Polygonum cuspidatum
In this study the phenolic compounds piceid, resveratrol and emodin were extracted from P. cuspidatum roots using ultrasound-assisted extraction. Multiple response surface methodology was used to optimize the extraction conditions of these phenolic compounds. A three-factor and three-level Box-Behnken experimental design was employed to evaluate the effects of the operation parameters, including extraction temperature (30-70 °C), ethanol concentration (40%-80%), and ultrasonic power (90-150 W), on the extraction yields of piceid, resveratrol, and emodin. The statistical models built from multiple response surface methodology were developed for the estimation of the extraction yields of multi-phenolic components. Based on the model, the extraction yields of piceid, resveratrol, and emodin can be improved by controlling the extraction parameters. Under the optimum conditions, the extraction yields of piceid, resveratrol and emodin were 10.77 mg/g, 3.82 mg/g and 11.72 mg/g, respectively
Constraining properties of neutron stars with heavy-ion reactions in terrestrial laboratories
Heavy-ion reactions provide a unique means to investigate the equation of
state (EOS) of neutron-rich nuclear matter, especially the density dependence
of the nuclear symmetry energy . The latter plays an important
role in understanding many key issues in both nuclear physics and astrophysics.
Recent analyses of heavy-ion reactions have already put a stringent constraint
on the around the saturation density. This subsequently allowed
us to constrain significantly the radii and cooling mechanisms of neutron stars
as well as the possible changing rate of the gravitational constant G.Comment: 6 pages. Talk given at the Nuclear Physics in Astrophysics III,
Dresden, Germany, March 26-31, 2007. To appear in a special volume of J. of
Phys.
Spin-glass ground state in a triangular-lattice compound YbZnGaO
We report on comprehensive results identifying the ground state of a
triangular-lattice structured YbZnGaO to be spin glass, including no
long-range magnetic order, prominent broad excitation continua, and absence of
magnetic thermal conductivity. More crucially, from the ultralow-temperature
a.c. susceptibility measurements, we unambiguously observe frequency-dependent
peaks around 0.1 K, indicating the spin-glass ground state. We suggest this
conclusion to hold also for its sister compound YbMgGaO, which is confirmed
by the observation of spin freezing at low temperatures. We consider disorder
and frustration to be the main driving force for the spin-glass phase.Comment: Version as accepted to PR
Plaquette Ordering in SU(4) Antiferromagnets
We use fermion mean field theory to study possible plaquette ordering in the
antiferromagnetic SU(4) Heisenberg model. We find the ground state for both the
square and triangular lattices to be the disconnected plaquette state. Our mean
field theory gives a first order transition for plaquette ordering for the
triangular lattice. Our results suggest a large number of low lying states.Comment: 16 pages, 5 figure
Urban energy consumption and CO2 emissions in Beijing: current and future
This paper calculates the energy consumption and CO2 emissions of Beijing over 2005–2011 in light of the Beijing’s energy balance table and the carbon emission coefficients of IPCC. Furthermore, based on a series of energy conservation planning program issued in Beijing, the Long-range Energy Alternatives Planning System (LEAP)-BJ model is developed to study the energy consumption and CO2 emissions of Beijing’s six end-use sectors and the energy conversion sector over 2012–2030 under the BAU scenario and POL scenario. Some results are found in this research: (1) During 2005–2011, the energy consumption kept increasing, while the total CO2 emissions fluctuated obviously in 2008 and 2011. The energy structure and the industrial structure have been optimized to a certain extent. (2) If the policies are completely implemented, the POL scenario is projected to save 21.36 and 35.37 % of the total energy consumption and CO2 emissions than the BAU scenario during 2012 and 2030. (3) The POL scenario presents a more optimized energy structure compared with the BAU scenario, with the decrease of coal consumption and the increase of natural gas consumption. (4) The commerce and service sector and the energy conversion sector will become the largest contributor to energy consumption and CO2 emissions, respectively. The transport sector and the industrial sector are the two most potential sectors in energy savings and carbon reduction. In terms of subscenarios, the energy conservation in transport (TEC) is the most effective one. (5) The macroparameters, such as the GDP growth rate and the industrial structure, have great influence on the urban energy consumption and carbon emissions
Probing the nuclear equation of state by production in heavy ion collisions
The dependence of production on the nuclear equation of state is
investigated in heavy ion collisions. An increase of the excitation function of
multiplicities obtained in heavy () over light () systems
when going far below threshold which has been observed by the KaoS
Collaboration strongly favours a soft equation of state. This observation holds
despite of the influence of an in-medium kaon potential predicted by effective
chiral models which is necessary to reproduce the experimental yields.Comment: 4 pages Revtex, 4 PS figures, to appear in Phys. Rev. Let
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