Multi-partite entanglement and quantum phase transition in the one-, two-, and three-dimensional transverse field Ising model

In this paper we consider the quantum phase transition in the Ising model in the presence of a transverse field in one, two and three dimensions from a multi-partite entanglement point of view. Using \emph{exact} numerical solutions, we are able to study such systems up to 25 qubits. The Meyer-Wallach measure of global entanglement is used to study the critical behavior of this model. The transition we consider is between a symmetric GHZ-like state to a paramagnetic product-state. We find that global entanglement serves as a good indicator of quantum phase transition with interesting scaling behavior. We use finite-size scaling to extract the critical point as well as some critical exponents for the one and two dimensional models. Our results indicate that such multi-partite measure of global entanglement shows universal features regardless of dimension $d$. Our results also provides evidence that multi-partite entanglement is better suited for the study of quantum phase transitions than the much studied bi-partite measures.Comment: 7 pages, 8 Figures. To appear in Physical Review

Adiabatic entanglement transport in Rydberg aggregates

We consider the interplay between excitonic and atomic motion in a regular, flexible chain of Rydberg atoms, extending our recent results on entanglement transport in Rydberg chains [W\"uster et al., Phys.Rev.Lett 105 053004 (2010)]. In such a Rydberg chain, similar to molecular aggregates, an electronic excitation is delocalised due to long range dipole-dipole interactions among the atoms. The transport of an exciton that is initially trapped by a chain dislocation is strongly coupled to nuclear dynamics, forming a localised pulse of combined excitation and displacement. This pulse transfers entanglement between dislocated atoms adiabatically along the chain. Details about the interaction and the preparation of the initial state are discussed. We also present evidence that the quantum dynamics of this complex many-body problem can be accurately described by selected quantum-classical methods, which greatly simplify investigations of excitation transport in flexible chains

Vibration-enhanced quantum transport

In this paper, we study the role of collective vibrational motion in the phenomenon of electronic energy transfer (EET) along a chain of coupled electronic dipoles with varying excitation frequencies. Previous experimental work on EET in conjugated polymer samples has suggested that the common structural framework of the macromolecule introduces correlations in the energy gap fluctuations which cause coherent EET. Inspired by these results, we present a simple model in which a driven nanomechanical resonator mode modulates the excitation energy of coupled quantum dots and find that this can indeed lead to an enhancement in the transport of excitations across the quantum network. Disorder of the on-site energies is a key requirement for this to occur. We also show that in this solid state system phase information is partially retained in the transfer process, as experimentally demonstrated in conjugated polymer samples. Consequently, this mechanism of vibration enhanced quantum transport might find applications in quantum information transfer of qubit states or entanglement.Comment: 7 pages, 6 figures, new material, included references, final published versio

Quantum transport in quantum networks and photosynthetic complexes at the steady state

Recently, several works have analysed the efficiency of photosynthetic complexes in a transient scenario and how that efficiency is affected by environmental noise. Here, following a quantum master equation approach, we study the energy and excitation transport in fully connected networks both in general and in the particular case of the Fenna-Matthew-Olson complex. The analysis is carried out for the steady state of the system where the excitation energy is constantly "flowing" through the system. Steady state transport scenarios are particularly relevant if the evolution of the quantum system is not conditioned on the arrival of individual excitations. By adding dephasing to the system, we analyse the possibility of noise-enhancement of the quantum transport.Comment: 10 pages, single column, 6 figures. Accepted for publication in Plos On

Psychiatric disorders in Iranian children and adolescents

Objective: The aim of the present study was to investigate the epidemiology of psychiatric disorders in children and adolescents in five provinces of Iran: Tehran, Shiraz, Isfahan, Tabriz and Mashhad. Method: In the present study, we selected 9,636 children and adolescents aged 6-18 years through multistage cluster random sampling method from Tehran, Shiraz, Isfahan, Tabriz and Mashhad. We instructed the clinical psychologists to complete the Strengths and Difficulties Questionnaire (SDQ) for the participants, and those who received a high score on SDQ, completed the Persian version of Kiddie-SADS-Present and Lifetime Version (K-SADS-PL). We used descriptive analysis and 95 confidence interval to investigate the relationship between scores of the K- SADS questionnaire and demographic factors . We used one-way ANOVA to test the significant differences among the disorders according to sex, age and province of residence. Results: Based on the results, oppositional defiant disorder (ODD) (4.45) had the highest prevalence of psychiatric disorders in the five provinces and substance abuse and alcohol abuse (0) had the lowest prevalence. In addition, attention deficit hyperactivity disorder (ADHD) had the most prevalence in boys (5.03) and ODD had the most prevalence in girls (4.05). Among the three age groups, 6 to 9 year olds had the highest rates of ADHD (5.69); 10 to 14 and 15 to 18 year olds had the highest rates of ODD (4.32 and 4.37 respectively). Among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Conclusion: The current study revealed that the overall frequency of psychiatric disorders based on Kiddie- SADS-Present and Lifetime Version (K-SADS-PL) was higher than a similar study. Moreover, in this study, among the five provinces, Tehran and Mashhad allocated the highest rates of ODD; Isfahan and Shiraz had the highest rates of ADHD; and Tabriz had the highest rates of social phobia. Therefore, these percentage of psychiatric disorders in Iran lead us toward a greater use of consultation and mental health services

Effect of barberry (Berberis vulgaris) consumption on blood pressure, plasma lipids, and inflammation in patients with hypertension and other cardiovascular risk factors: study protocol for a randomized clinical trial

Background: Cardiovascular diseases (CVDs) remain the leading causes of morbidity and mortality in the world. Hypertension is an important and prevalent cardiovascular risk factor. The present study will be conducted to investigate the effect of barberry as a cardio-protective fruit on the blood pressure in patients with hypertension and other CVD risk factors. Furthermore, plasma concentrations of lipids and inflammatory biomarkers will be evaluated. Methods/design: This is an 8-week, prospective, single-blinded, parallel assigned, randomized controlled clinical trial (RCT) in which eligible men and women with hypertension and other cardiovascular risk factors will be randomized to either placebo powder (PP; containing 9 g maltodextrin, 1 g citric acid, 1 g milled sucrose and edible red color (n = 37)) or barberry powder (BP; containing 10 g milled dried barberry and 1 g of milled sucrose (n = 37)) groups. At baseline and after 8 weeks of intervention, plasma lipids and inflammatory markers, 24-h urinary nitrite/nitrate and sodium excretion, and 24-h ambulatory blood pressure monitoring (ABPM) will be measured. Anthropometric measures and dietary assessment will be performed as well. Data analysis will be done using SPSS version-21 software. Discussion: The interest in natural and functional food products has increased globally. This RCT will add to the growing literature for the potential antihypertensive, lipid-lowering, and anti-inflammatory effects of barberry in humans. Trial registration: ClinicalTrials.gov (NCT number) NCT04084847. Registered on 10 December 2019