Interfacing a quantum dot spin with a photonic circuit

A scalable optical quantum information processor is likely to be a waveguide circuit with integrated sources, detectors, and either deterministic quantum-logic or quantum memory elements. With microsecond coherence times, ultrafast coherent control, and lifetime-limited transitions, semiconductor quantum-dot spins are a natural choice for the static qubits. However their integration with flying photonic qubits requires an on-chip spin-photon interface, which presents a fundamental problem: the spin-state is measured and controlled via circularly-polarised photons, but waveguides support only linear polarisation. We demonstrate here a solution based on two orthogonal photonic nanowires, in which the spin-state is mapped to a path-encoded photon, thus providing a blue-print for a scalable spin-photon network. Furthermore, for some devices we observe that the circular polarisation state is directly mapped to orthogonal nanowires. This result, which is physically surprising for a non-chiral structure, is shown to be related to the nano-positioning of the quantum-dot with respect to the photonic circuit

Experimenting with concepts from modular product design and multi-objective optimization to benefit people living in poverty

Every discipline has its own specific knowledge that has been accumulated and refined over time. In the aerospace industry, for example, the domain knowledge of multidisciplinary optimization has grown and matured. The same has happened with domain knowledge related to modularity in the consumer product design industry. Knowledge from these domains has carried over to other domains such as automotive, medical, and defense, and has enabled advances in these disciplines. One domain that has been underserved by the advanced engineering methodologies coming from other disciplines is the domain of design for the developing world. Exploring the use of engineering domain knowledge to alleviate poverty is a valuable study that will open opportunities to use engineering to benefit resource poor individuals. This paper explores the domain knowledge of modularity and multi-objective optimization and applies it to the domain of design for the developing world by introducing the concept of collaborative products to assist the resource poor individuals. Can knowledge from one domain be used in a new domain, and if so, what would it look like? In this paper, a general methodology is presented, followed by a simple example to illustrate the design of a collaborative product for the developing world. The paper suggests that by using domain knowledge from a non-related domain paired with the method presented, products can be designed and optimized for collaborative performance with potential to both generate new income and save money for the end customers

Global Review of the Age Distribution of Rotavirus Disease in Children Aged < 5 Years Before the Introduction of Rotavirus Vaccination

International audienceWe sought datasets with granular age distributions of rotavirus-positive disease presentations among children <5 years of age, before the introduction of rotavirus vaccines. We identified 117 datasets and fit parametric age distributions to each country dataset and mortality stratum. We calculated the median age and the cumulative proportion of rotavirus gastroenteritis events expected to occur at ages between birth and 5.0 years. The median age of rotavirus-positive hospital admissions was 38 weeks (interquartile range [IQR], 25-58 weeks) in countries with very high child mortality and 65 weeks (IQR, 40-107 weeks) in countries with very low or low child mortality. In countries with very high child mortality, 69% of rotavirus-positive admissions in children <5 years of age were in the first year of life, with 3% by 10 weeks, 8% by 15 weeks, and 27% by 26 weeks. This information is critical for assessing the potential benefits of alternative rotavirus vaccination schedules in different countries and for monitoring program impact