Coherent Time Evolution and Boundary Conditions of Two-Photon Quantum Walks

Multi-photon quantum walks in integrated optics are an attractive controlled quantum system, that can mimic less readily accessible quantum systems and exhibit behavior that cannot in general be accurately replicated by classical light without an exponential overhead in resources. The ability to observe time evolution of such systems is important for characterising multi-particle quantum dynamics---notably this includes the effects of boundary conditions for walks in spaces of finite size. Here we demonstrate the coherent evolution of quantum walks of two indistinguishable photons using planar arrays of 21 evanescently coupled waveguides fabricated in silicon oxynitride technology. We compare three time evolutions, that follow closely a model assuming unitary evolution, corresponding to three different lengths of the array---in each case we observe quantum interference features that violate classical predictions. The longest array includes reflecting boundary conditions.Comment: 7 pages,7 figure

The nonrelativistic limit of the Majorana equation and its simulation in trapped ions

We analyze the Majorana equation in the limit where the particle is at rest. We show that several counterintuitive features, absent in the rest limit of the Dirac equation, do appear. Among them, Dirac-like positive energy solutions that turn into negative energy ones by free evolution, or nonstandard oscillations and interference between real and imaginary spinor components for complex solutions. We also study the ultrarelativistic limit, showing that the Majorana and Dirac equations mutually converge. Furthermore, we propose a physical implementation in trapped ions.Comment: 7 pages, 1 figure. Proceedings of 18th Central European Workshop on Quantum Optics (CEWQO 2011), Madrid, Spai

Exclusive Breastfeeding for at Least Four Months Is Associated with a Lower Prevalence of Overweight and Obesity in Mothers and Their Children after 2–5 Years from Delivery

INTRODUCTION: Obesity is a current public health concern. Higher body weight is influenced by genetic and environmental parameters, and their interplay and is associated with a greater risk for several chronic diseases. Breastfeeding has been suggested as a preventive measure against obesity, which can further reduce long-term negative health outcomes for both women and children. AIM: The aim of the present study was to evaluate the role of breastfeeding on maternal and childhood overweight and obesity. MATERIALS AND METHODS: This is a cross-sectional study conducted on 2515 healthy mothers and their children, aged 2-5 years, enrolled from nine different Greek rural and urban regions. Validated, standardized questionnaires were administrated that included anthropometric indices, socio-demographic characteristics of mothers and children, as well as breastfeeding practices. RESULTS: Overall, 68% of participated women exclusively breastfed their children for at least 4 months. Mothers that exclusively breastfed showed a significantly lower prevalence of overweight and obesity after 2-5 years from delivery (p \u3c 0.0001). Children that had exclusively been breastfed showed a significantly lower prevalence of overweight and obesity at the age of 2-5 years (p \u3c 0.0001). Using multivariate regression analysis, exclusive breastfeeding for at least 4 months was associated with a two-fold lower risk for maternal and childhood overweight and obesity after 2-5 years from delivery, independent from maternal age, educational and economic status, and smoking habits (p \u3c 0.0001). CONCLUSION: Exclusive breastfeeding for at least 4 months had a positive effect on childhood overweight and obesity, also contributing beneficially to post-natal maternal weight control. The beneficial effects of breastfeeding should be communicated to future and new mothers, while supportive actions for all mothers to initiate and continue breastfeeding their offspring should be implemented

Pre-Pregnancy Excess Weight Association with Maternal Sociodemographic, Anthropometric and Lifestyle Factors and Maternal Perinatal Outcomes

BACKGROUND: Pre-pregnancy excess weight is an important factor for adverse maternal perinatal outcomes; however, data for Greek women remain limited. Therefore, the aim of the present work was to evaluate the relation between pre-pregnant weight status and sociodemographic, anthropometric and lifestyle factors and maternal perinatal outcomes. METHODS: In the present cross-sectional study, 5133 healthy women were enrolled from nine different Greek regions after applying specific inclusion and exclusion criteria. Validated questionnaires were used to assess the sociodemographic characteristics and certain lifestyle factors of the study population. Anthropometric and clinical data were retrieved from medical history files of the women, including measured weight in the first weeks of pregnancy and right before delivery, and maternal perinatal outcomes. Women\u27s weights and heights were also measured 2-5 years postpartum by trained nutritionists. Non-adjusted and adjusted statistical analysis was performed to assess whether pre-pregnancy weight status was associated with sociodemographic, anthropometric and lifestyle factors and maternal perinatal outcomes. RESULTS: In pre-pregnancy, 17.5% of the women were overweight, and 4.9% were classified as obese. These rates were increased 2-5 years postpartum, reaching 21.0% for overweight and 9.6% for obese women. Pre-pregnancy overweight/obesity were associated with older maternal age, higher prevalence of overweight/obesity at 2-5 years postpartum and nonexclusive breastfeeding, as well as increased rates for preterm birth and pregnancy-induced hypertension after multiple adjustments. CONCLUSIONS: Overweight and obesity rates were high among women of childbearing age in Greece. These findings highlight the urgent need for healthy lifestyle promotion and targeted obesity prevention and intervention schemes among women of reproductive age

Quantum walks of correlated particles

Quantum walks of correlated particles offer the possibility to study large-scale quantum interference, simulate biological, chemical and physical systems, and a route to universal quantum computation. Here we demonstrate quantum walks of two identical photons in an array of 21 continuously evanescently-coupled waveguides in a SiOxNy chip. We observe quantum correlations, violating a classical limit by 76 standard deviations, and find that they depend critically on the input state of the quantum walk. These results open the way to a powerful approach to quantum walks using correlated particles to encode information in an exponentially larger state space

Matter-wave interferometers using TAAP rings

We present two novel matter-wave Sagnac interferometers based on ring-shaped time-averaged adiabatic potentials (TAAP). For both the atoms are put into a superposition of two different spin states and manipulated independently using elliptically polarized rf-fields. In the first interferometer the atoms are accelerated by spin-state-dependent forces and then travel around the ring in a matter-wave guide. In the second one the atoms are fully trapped during the entire interferometric sequence and are moved around the ring in two spin-state-dependent `buckets'. Corrections to the ideal Sagnac phase are investigated for both cases. We experimentally demonstrate the key atom-optical elements of the interferometer such as the independent manipulation of two different spin states in the ring-shaped potentials under identical experimental conditions

Relation of Maternal Pre-Pregnancy Factors and Childhood Asthma: A Cross-Sectional Survey in Pre-School Children Aged 2–5 Years Old

Background and Objectives: Asthma constitutes a constant, prolonged, inflammation-related pulmonary disorder in childhood with serious public health concerns. Several maternal risk factors can enhance the prevalence of its development in this stage of life; however, the currently available data remain contradictory and/or inconsistent. We aim to evaluate the potential impacts of mothers\u27 sociodemographic, anthropometric and prenatal and perinatal factors on the prevalence of developing asthma in pre-school children. Materials and Methods: This is a retrospective cross-sectional survey, which includes 5133 women and their matched pre-school children. Childhood asthma was diagnosed using validated questionnaires. Statistical analysis was accomplished to evaluate whether maternal sociodemographic, anthropometric and prenatal and perinatal factors can increase the probability of childhood asthma in pre-school age. Results: A prevalence of 4.5% of childhood asthma was recorded in pre-school age. Maternal age and pre-pregnancy overweight and obesity, caesarean section, gestational diabetes and hypertension and not breastfeeding were associated with childhood asthma after adjustment for multiple confounding factors. Conclusion: Our research showed that several maternal factors increase the prevalence of childhood asthma in pre-school age. Suitable and effective health policies and strategies should be taken into account to confront the predominant maternal factors that increase its prevalence in pre-school age