Quantum Walk Topology and Spontaneous Parametric Down Conversion

In a recent detailed research program we proposed to study the complex physics of topological phases by an all optical implementation of a discrete-time quantum walk. The main novel ingredient proposed for this study is the use of non-linear parametric amplifiers in the network which could in turn be used to emulate intra-atomic interactions and thus analyze many-body effects in topological phases even when using light as the quantum walker. In this paper, and as a first step towards the implementation of our scheme, we analize the interplay between quantum walk lattice topology and spatial correlations of bi-photons produced by spontaneous parametric down-conversion. We also describe different detection methods suitable for our proposed experimental scheme.Comment: 7 pages, 3 figures. arXiv admin note: substantial text overlap with arXiv:1409.127

No. 15: The State of Food Security in Manzini, Swaziland

This study of the food security situation of the poor in Manzini, Swaziland’s economic hub, formed part of AFSUN’s baseline survey of eleven Southern African cities. It found that the urban poor here are less food secure than in any of the other cities in the survey. On the basis of the findings presented in this paper, AFSUN makes several policy recommendations to deal with food security challenges in the poor urban areas of Swaziland. Among these is that government needs to target urban households specifically in addition to its focus on poverty in rural areas. A more national approach that covers both rural and urban areas will help Swaziland to move towards the achievement of the Millennium Development Goal to reduce hunger by 50%. Because households that are severely food insecure tend to be large, female-headed and female-centred, and have a narrow range of livelihood strategies, it is vital for policies that address urban food security to appreciate the complex relationship between household food security and a range of variables such as income, gender and household size

Rural-Urban Economic Linkages: The Case of Dodoma Region, Tanzania

The government of Tanzania has been active in attempting to stimulate national economic development since independence, and has used such methods as concentration of rural population in village settlements, the promotion of nine growth centres into secondary cities, and the decentralisation of both the decision-making machinery and economic activities, in particular industry, from Dar-es-Salaam, but with only limited success. Tanzania is still using the basic pattern of urban centres and structures developed during the colonial period, and the problem is that this pattern was designed to serve a different function and purpose from that of today. This study aims to evaluate Tanzania's current urban spatial structure, and the associated economic linkages, in relation to its present development goals. Specifically, it attempts to evaluate one aspect of the spatial economic structure, that of the urban hierarchy, in facilitating the flows of goods, services and information between the rural and urban sectors of the country. This is approached by evaluating the extent to which existing spatial structure has reduced both the primacy of Dar-es-Salaam and the existence of regional inequalities, has attracted industrial growth away from the coastal and northern zones, and has achieved the development objectives of the state of Tanzania. The results of this study show that the dominance of the coastal areas, and, in particular, the metropolitan city of Dar-es-Salaam, the northern centres of Arusha, Moshi, Tanga and Morogoro over the other centres and regions of Tanzania, has not been weakened. The growth centre strategy has not been able to reduce either urban primacy, and in particular the primacy of Dar-es-Salaam, or regional inequalities. It can be concluded that although Tanzania's development goals have changed sincelndependence, the spatial organisation of its towns and service centres, its communication and transport networks and the economic links between them have remained largely unchanged. The present urban structure in Tanzania, and the Dodoma study region, is not appropriate for the nation's current development goals, and has not succeeded in bringing about either the desired rural development or regional equity