354 research outputs found
Robust Entanglement in Anti-ferromagnetic Heisenberg Chains by Single-spin Optimal Control
We demonstrate how near-perfect entanglement (in fact arbitrarily close to
maximal entanglement) can be generated between the end spins of an
anti-ferromagnetic isotropic Heisenberg chain of length , starting from the
ground state in the excitation subspace, by applying a magnetic field
along a given direction, acting on a single spin only. Temporally optimal
magnetic fields to generate a singlet pair between the two end spins of the
chain are calculated for chains up to length 20 using optimal control theory.
The optimal fields are shown to remain effective in various non-ideal
situations including thermal fluctuations, magnetic field leakage, random
system couplings and decoherence. Furthermore, the quality of the entanglement
generated can be substantially improved by taking these imperfections into
account in the optimization. In particular, the optimal pulse of a given
thermal initial state is also optimal for any other initial thermal state with
lower temperature.Comment: 10 pages, revte
Entanglement probe of two-impurity Kondo physics in a spin chain
We propose that real-space properties of the two-impurity Kondo model can be
obtained from an effective spin model where two single-impurity Kondo spin
chains are joined via an RKKY interaction between the two impurity spins. We
then use a DMRG approach, valid in all ranges of parameters, to study its
features using two complementary quantum-entanglement measures, the negativity
and the von Neumann entropy. This non-perturbative approach enables us to
uncover the precise dependence of the spatial extent of the Kondo
screening cloud with the Kondo and RKKY couplings. Our results reveal an
exponential suppression of the Kondo temperature with the
size of the effective impurity spin in the limit of large ferromagnetic RKKY
coupling, a striking display of "Kondo resonance narrowing" in the two-impurity
Kondo model. We also show how the antiferromagnetic RKKY interaction produces
an effective decoupling of the impurities from the bulk already for
intermediate strengths of this interaction, and, furthermore, exhibit how the
non-Fermi liquid quantum critical point is signaled in the quantum entanglement
between various parts of the system.Comment: 5 pages, 5 figure
Nonequilibrium critical scaling from quantum thermodynamics
The emerging field of quantum thermodynamics is contributing important
results and insights into archetypal many-body problems, including quantum
phase transitions. Still, the question whether out-of-equilibrium quantities,
such as fluctuations of work, exhibit critical scaling after a sudden quench in
a closed system has remained elusive. Here, we take a novel approach to the
problem by studying a quench across an impurity quantum critical point. By
performing density matrix renormalization group computations on the
two-impurity Kondo model, we are able to establish that the irreversible work
produced in a quench exhibits finite-size scaling at quantum criticality. This
scaling faithfully predicts the equilibrium critical exponents for the
crossover length and the order parameter of the model, and, moreover, implies a
new exponent for the rescaled irreversible work. By connecting the irreversible
work to the two-impurity spin correlation function, our findings can be tested
experimentally.Comment: 6 pages, 4 figure
Effects of the alcoholic extract of white mulberry leaves on behavioral performance of rats
White mulberry tree is a genus of Morus in the family Moraceae. The leaves and root of this tree have been traditionally medical applications as a laxative, analgesic, diuretic, antitussive, and sedative agent as well as for reducing blood pressure. The present study aimed to investigate the effects of the alcoholic extract of the leaves of white mulberry tree on the behavioral performance of rats. In this study, 24 male Wistar rats were kept under the condition of normal 12-12 h light-dark cycle for adaptation with the animal house environment and experiments location (23-27C0). All animals have access to food and water ad libitum and were weighed weekly to control their natural growth. These rats were divided into four groups of six rats. First, the open field behavioral test was performed on all rats and after 35 days the gavage feeding of the alcoholic extract of white mulberry leaves was performed. Group one received distilled water and groups two to four respectively received concentrations of 150, 300, and 600 mg per unit body weight of the alcoholic extract white mulberry leaves. Then, open field behavioral test was performed again. Results showed that regarding the number of visited zones there is a significant difference between the control group and the groups receiving the extract. Up to the sixth week that the condition of all rats was identical the rate of weight increase was the same and from the seventh week on that the gavage of the hydro-alcoholic extract of white mulberry leaves began, the trend of the weight increase of the control group was different than that of the other groups. due to the effect of the alcoholic extract of white mulberry leaves on the weight of the rats at concentrations above, it can be concluded that the extract is effective for weight loss. Findings of open field test showed that this extract has anti-anxiety effects while imposing no toxic effects
Hybrid Extended Kalman Filtering and Noise Statistics Optimization for Produce Wash State Estimation
Food-borne diseases associated with fresh produce consistently cause serious public health issues. Although sanitization measures are utilized to enhance the safety of fresh produce, strategies that neglect the dynamic nature of commercial wash processes are limited, creating the potential for pathogen cross-contamination and major disease outbreaks. In light of this risk, there is an urgent need for new control approaches during produce washing to reduce the probability of outbreaks. As an important step in this direction, a hybrid extended Kalman filter (HEKF) and particle swarm optimization (PSO)-based noise statistics optimization are designed for a produce wash system. The HEKF uses discrete-time free chlorine (FC) measurements, and PSO is used to optimize the noise statistics of the process noise model. The process model and HEKF enable the estimation of chemical oxygen demand (COD) in the water wash, FC concentration, Escherichia coli concentration (PC) in the water wash, and E. coli level (P) on the lettuce. Although control is not explicitly addressed in this paper, the estimation technique proposed here will enable not only monitoring but also advanced control methods. The HEKF is applied to estimate E. coli O157:H7 contamination of shredded lettuce during an industrial wash. The HEKF estimates COD with a root mean square error (RSME) of 8.24 mg/L, FC concentration with an RMSE of 0.09 mg/L, PC in the wash water with an RMSE of 0.19 MPN/ml, and P on the lettuce with an RSME of 0.04 MPN/g. A sensitivity analysis demonstrates that the estimator has good robustness
An Extensive Set of Kinematic and Kinetic Data for Individuals with Intact Limbs and Transfemoral Prosthesis Users
This paper introduces an extensive human motion data set for typical activities of daily living. These data are crucial for the design and control of prosthetic devices for transfemoral prosthesis users. This data set was collected from seven individuals, including five individuals with intact limbs and two transfemoral prosthesis users. These data include the following types of movements: (1) walking at three different speeds; (2) walking up and down a 5-degree ramp; (3) stepping up and down; (4) sitting down and standing up. We provide full-body marker trajectories and ground reaction forces (GRFs) as well as joint angles, joint velocities, joint torques, and joint powers. This data set is publicly available at the website referenced in this paper. Data from flexion and extension of the hip, knee, and ankle are presented in this paper. However, the data accompanying this paper (available on the internet) include 46 distinct measurements and can be useful for validating or generating mathematical models to simulate the gait of both transfemoral prosthesis users and individuals with intact legs
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