Full counting statistics and phase diagram of a dissipative Rydberg gas

Ultra-cold gases excited to strongly interacting Rydberg states are a promising system for quantum simulations of many-body systems. For off-resonant excitation of such systems in the dissipative regime, highly correlated many-body states exhibiting, among other characteristics, intermittency and multi-modal counting distributions are expected to be created. So far, experiments with Rydberg atoms have been carried out in the resonant, non-dissipative regime. Here we realize a dissipative gas of rubidium Rydberg atoms and measure its full counting statistics for both resonant and off-resonant excitation. We find strongly bimodal counting distributions in the off-resonant regime that are compatible with intermittency due to the coexistence of dynamical phases. Moreover, we measure the phase diagram of the system and find good agreement with recent theoretical predictions. Our results pave the way towards detailed studies of many-body effects in Rydberg gases.Comment: 12 pages, 5 figure

High-fidelity quantum driving

The ability to accurately control a quantum system is a fundamental requirement in many areas of modern science such as quantum information processing and the coherent manipulation of molecular systems. It is usually necessary to realize these quantum manipulations in the shortest possible time in order to minimize decoherence, and with a large stability against fluctuations of the control parameters. While optimizing a protocol for speed leads to a natural lower bound in the form of the quantum speed limit rooted in the Heisenberg uncertainty principle, stability against parameter variations typically requires adiabatic following of the system. The ultimate goal in quantum control is to prepare a desired state with 100% fidelity. Here we experimentally implement optimal control schemes that achieve nearly perfect fidelity for a two-level quantum system realized with Bose-Einstein condensates in optical lattices. By suitably tailoring the time-dependence of the system's parameters, we transform an initial quantum state into a desired final state through a short-cut protocol reaching the maximum speed compatible with the laws of quantum mechanics. In the opposite limit we implement the recently proposed transitionless superadiabatic protocols, in which the system perfectly follows the instantaneous adiabatic ground state. We demonstrate that superadiabatic protocols are extremely robust against parameter variations, making them useful for practical applications.Comment: 17 pages, 4 figure

Historical Missionary Activity, Schooling, and the Reversal of Fortunes: Evidence from Nigeria

This paper shows that historical missionary activity has had a persistent effect on schooling outcomes, and contributed to a reversal of fortunes wherein historically richer ethnic groups are poorer today. Combining contemporary individual-level data with a newly constructed dataset on mission stations in Nigeria, we find that individuals whose ancestors were exposed to greater missionary activity have higher levels of schooling. This effect is robust to omitted heterogeneity, ethnicity fixed effects, and reverse causation. We find inter-generational factors and the persistence of early advantages in educational infrastructure to be key channels through which the effect has persisted. Consistent with theory, the effect of missions on current schooling is larger for population subgroups that have historically suffered disadvantages in access to education

The complex remuneration of human resources for health in low-income settings: policy implications and a research agenda for designing effective financial incentives

Background Human resources for health represent an essential component of health systems and play a key role to accelerate progress towards universal health coverage. Many countries in sub-Saharan Africa face challenges regarding the availability, distribution and performance of health workers, which could be in part addressed by providing effective financial incentives. Methods Based on an overview of the existing literature, the paper highlights the gaps in the existing research in low-income countries exploring the different components of health workers' incomes. It then proposes a novel approach to the analysis of financial incentives and delineates a research agenda, which could contribute to shed light on this topic. Findings The article finds that, while there is ample research that investigates separately each of the incomes health workers may earn (for example, salary, fee-for-service payments, informal incomes, top-ups- and per diems, dual practice and non-health activities), there is a dearth of studies which look at the health workers' complex remuneration-, that is, the whole of the financial incentives available. Little research exists which analyses simultaneously all revenues of health workers, quantifies the overall remuneration and explores its complexity, its multiple components and their features, as well as the possible interaction between income components. However, such a comprehensive approach is essential to fully comprehend health workers' incentives, by investigating the causes (at individual and system level) of the fragmentation in the income structure and the variability in income levels, as well as the consequences of the complex remuneration- on motivation and performance. This proposition has important policy implications in terms of devising effective incentive packages as it calls for an active consideration of the role that complex remuneration- plays in determining recruitment, retention and motivation patterns, as well as, more broadly, the performance of health systems. Conclusions This paper argues that research focusing on the health workers' complex remuneration- is critical to address some of the most challenging issues affecting human resources for health. An empirical research agenda is proposed to fill the gap in our understanding.This article is about public relations expertise. It presents the results of an extensive empirical enquiry and is framed by the concept of profession and the sociological debates that surround it.sch_iih13pub3968pub6

Middle Class in Africa: Determinants and Consequences

This study complements the inclusive growth literature by examining the determinants and consequences of the middle class in a continent where economic growth has been relatively high. The empirical evidence is based on a sample of 33 African countries for a 2010 cross-sectional study. OLS, 2SLS, 3SLS and SUR estimation techniques are employed to regress a plethora of middle class indicators, notably, the: floating, middle-class with floating, middle-class without floating, lower-middle-income and upper-middle-income categories. Results can be classified into two main strands. First, results on determinants broadly show that GDP per capita and education positively affect all middle class dependent variables. However, we have seen a negative nexus for the effect of ethnic fragmentation, political stability in general and partially for economic vulnerability. Simple positive correlations have been observed for: the size of the informal sector, openness and democracy. Second, on the consequences, the middle class enables the accumulation of human and infrastructural capital, while its effect is null on political stability and democracy in the short-run but positive for governance and modernisation. Policy implications are discussed

History Matters: The Long Term Impact of Colonial Public Investments in French West Africa [Dataset]

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