Optimal Control for Generating Quantum Gates in Open Dissipative Systems

Optimal control methods for implementing quantum modules with least amount of relaxative loss are devised to give best approximations to unitary gates under relaxation. The potential gain by optimal control using relaxation parameters against time-optimal control is explored and exemplified in numerical and in algebraic terms: it is the method of choice to govern quantum systems within subspaces of weak relaxation whenever the drift Hamiltonian would otherwise drive the system through fast decaying modes. In a standard model system generalising decoherence-free subspaces to more realistic scenarios, openGRAPE-derived controls realise a CNOT with fidelities beyond 95% instead of at most 15% for a standard Trotter expansion. As additional benefit it requires control fields orders of magnitude lower than the bang-bang decouplings in the latter.Comment: largely expanded version, superseedes v1: 10 pages, 5 figure

Incorporating basic needs to reconcile poverty and ecosystem services

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordConservation managers frequently face the challenge of protecting and sustaining biodiversity without producing detrimental outcomes for (often poor) human populations that depend upon ecosystem services for their wellbeing. However, win-win solutions are often elusive and can mask trade-offs and negative outcomes for the wellbeing of particular groups of people. To deal with such trade-offs, approaches are needed to identify both ecological as well as social thresholds to determine the acceptable 'solution space' for conservation. Although human wellbeing as a concept has recently gained prominence among conservationists, they still lack tools to evaluate how their action affects human wellbeing in a given context. This paper presents the Theory of Human Needs in the context of conservation, building on an extensive historical application of needs approaches in international development. We detail an innovative participatory method, to evaluate how human needs are met, using locally relevant thresholds. We then establish the connections between human needs and ecosystem services. An application of this method in coastal East Africa identifies households who are in serious harm through not meeting different basic needs, and uncovers the role of ecosystem services in meeting these. Drawing from the international development and wellbeing literature, we suggest that this methodological approach, can help conservationists and planners balance poverty alleviation and biodiversity protection, ensure that conservation measures do not, at the very least, push individuals into serious harm and as a basis for monitoring the impacts of conservation on multidimensional poverty. This article is protected by copyright. All rights reserved.This paper results from the project Sustainable Poverty Alleviation from Coastal Ecosystem Services (SPACES) project number NE-K010484-1, funded by the Ecosystem Services for Poverty Alleviation (ESPA) programme. The ESPA programme is funded by the Department for International Development (DFID), the Economic and Social Research Council (ESRC), and the Natural Environment Research Council (NERC)

Rural protein insufficiency in a wildlife-depleted west African farm-forest landscape

Introduction: Wildlife is an important source of protein for many people in developing countries. Yet wildlife depletion due to overexploitation is common throughout the humid tropics and its effect on protein security, especially for vulnerable households, is poorly understood. This is problematic for both sustainable rural development and conservation management. Methods: This study investigates a key dimension of protein security in a cash-crop farming community living in a wildlife-depleted farm-forest landscape in SW Ghana, a region where protein–energy malnutrition persists. Specifically, we monitored protein sufficiency, defined as whether consumption met daily requirements, as benchmarked by recommended daily allowance (RDA). We focus on whether more vulnerable households were less likely to be able to meet their protein needs, where vulnerability was defined by wealth, agricultural season and gender of the household head. Our central hypothesis was: (a) vulnerable households are less likely to consume sufficient protein. In the context that most plant proteins were home-produced, so likely relatively accessible to all households, while most animal proteins were purchased, so likely less accessible to vulnerable households, we tested two further hypotheses: (b) vulnerable households depend more on plant protein to cover their protein needs; and (c) vulnerable households are less likely to earn sufficient cash income to meet their protein needs through purchased animal sources. Results: Between 14% and 60% of households (depending on plant protein content assumptions) consumed less than the RDA for protein, but neither protein consumption nor protein sufficiency co-varied with household vulnerability. Fish, livestock and food crops comprised 85% of total protein intake and strongly affected protein sufficiency. However, bushmeat remained an important protein source (15% of total consumption), especially during the post-harvest season when it averaged 26% of total protein consumption. Across the year, 89% of households experienced at least one occasion when they had insufficient income to cover their protein needs through animal protein purchases. The extent of this income shortage was highest during the lean season and among poorer households. Conclusions: These findings indicate that despite wildlife depletion, bushmeat continues to make a substantial contribution to protein consumption, especially during the agricultural lean season. Income shortages among farmers limit their ability to purchase bushmeat or its substitutes, suggesting that wildlife depletion may cause malnutrition

Elasticity in ecosystem services: Exploring the variable relationship between ecosystems and human well-being

Although ecosystem services are increasingly recognized as benefits people obtain from nature, we still have a poor understanding of how they actually enhance multidimensional human well-being, and how well-being is affected by ecosystem change. We develop a concept of “ecosystem service elasticity” (ES elasticity) that describes the sensitivity of human well-being to changes in ecosystems. ES Elasticity is a result of complex social and ecological dynamics and is context dependent, individually variable, and likely to demonstrate nonlinear dynamics such as thresholds and hysteresis. We present a conceptual framework that unpacks the chain of causality from ecosystem stocks through flows, goods, value, and shares to contribute to the well-being of different people. This framework builds on previous conceptualizations, but places multidimensional well-being of different people as the final element. This ultimately disaggregated approach emphasizes how different people access benefits and how benefits match their needs or aspirations. Applying this framework to case studies of individual coastal ecosystem services in East Africa illustrates a wide range of social and ecological factors that can affect ES elasticity. For example, food web and habitat dynamics affect the sensitivity of different fisheries ecosystem services to ecological change. Meanwhile high cultural significance, or lack of alternatives enhance ES elasticity, while social mechanisms that prevent access can reduce elasticity. Mapping out how chains are interlinked illustrates how different types of value and the well-being of different people are linked to each other and to common ecological stocks. We suggest that examining chains for individual ecosystem services can suggest potential interventions aimed at poverty alleviation and sustainable ecosystems while mapping out of interlinkages between chains can help to identify possible ecosystem service trade-offs and winners and losers. We discuss conceptual and practical challenges of applying such a framework and conclude on its utility as a heuristic for structuring interdisciplinary analysis of ecosystem services and human wellbeing.This paper results from the project Sustainable Poverty Alleviation from Coastal Ecosystem Services (SPACES) project number NE-K010484-1, funded by the Ecosystem Services for Poverty Alleviation (ESPA) programme. The ESPA programme is funded by the Department for International Development (DFID), the Economic and Social Research Council (ESRC), and the Natural Environment Research Council (NERC).

Zermelo Navigation in the Quantum Brachistochrone

We analyse the optimal times for implementing unitary quantum gates in a constrained finite dimensional controlled quantum system. The family of constraints studied is that the permitted set of (time dependent) Hamiltonians is the unit ball of a norm induced by an inner product on su(n). We also consider a generalisation of this to arbitrary norms. We construct a Randers metric, by applying a theorem of Shen on Zermelo navigation, the geodesics of which are the time optimal trajectories compatible with the prescribed constraint. We determine all geodesics and the corresponding time optimal Hamiltonian for a specific constraint on the control i.e. k (Tr(Hc(t)^2) = 1 for any given value of k > 0. Some of the results of Carlini et. al. are re-derived using alternative methods. A first order system of differential equations for the optimal Hamiltonian is obtained and shown to be of the form of the Euler Poincare equations. We illustrate that this method can form a methodology for determining which physical substrates are effective at supporting the implementation of fast quantum computation

Site-specific labeling of nucleotides for making RNA for high resolution NMR studies using an E. coli strain disabled in the oxidative pentose phosphate pathway

Escherichia coli (E. coli) is a versatile organism for making nucleotides labeled with stable isotopes (13C, 15N, and/or 2H) for structural and molecular dynamics characterizations. Growth of a mutant E. coli strain deficient in the pentose phosphate pathway enzyme glucose-6-phosphate dehydrogenase (K10-1516) on 2-13C-glycerol and 15N-ammonium sulfate in Studier minimal medium enables labeling at sites useful for NMR spectroscopy. However, 13C-sodium formate combined with 13C-2-glycerol in the growth media adds labels to new positions. In the absence of labeled formate, both C5 and C6 positions of the pyrimidine rings are labeled with minimal multiplet splitting due to 1JC5C6 scalar coupling. However, the C2/C8 sites within purine rings and the C1′/C3′/C5′ positions within the ribose rings have reduced labeling. Addition of 13C-labeled formate leads to increased labeling at the base C2/C8 and the ribose C1′/C3′/C5′ positions; these new specific labels result in two- to three-fold increase in the number of resolved resonances. This use of formate and 15N-ammonium sulfate promises to extend further the utility of these alternate site specific labels to make labeled RNA for downstream biophysical applications such as structural, dynamics and functional studies of interesting biologically relevant RNAs

COVID-19, systemic crisis, and possible implications for the wild meat trade in sub-Saharan Africa

Wild animals play an integral and complex role in the economies and ecologies of many countries across the globe, including those of West and Central Africa, the focus of this policy perspective. The trade in wild meat, and its role in diets, have been brought into focus as a consequence of discussions over the origins of COVID-19. As a result, there have been calls for the closure of China’s “wet markets”; greater scrutiny of the wildlife trade in general; and a spotlight has been placed on the potential risks posed by growing human populations and shrinking natural habitats for animal to human transmission of zoonotic diseases. However, to date there has been little attention given to what the consequences of the COVID-19 economic shock may be for the wildlife trade; the people who rely on it for their livelihoods; and the wildlife that is exploited. In this policy perspective, we argue that the links between the COVID-19 pandemic, rural livelihoods and wildlife are likely to be more complex, more nuanced, and more far-reaching, than is represented in the literature to date. We develop a causal model that tracks the likely implications for the wild meat trade of the systemic crisis triggered by COVID-19. We focus on the resulting economic shockwave, as manifested in the collapse in global demand for commodities such as oil, and international tourism services, and what this may mean for local African economies and livelihoods. We trace the shockwave through to the consequences for the use of, and demand for, wild meats as households respond to these changes. We suggest that understanding and predicting the complex dynamics of wild meat use requires increased collaboration between environmental and resource economics and the ecological and conservation sciences

Exploiting Matrix Symmetries and Physical Symmetries in Matrix Product States and Tensor Trains

We focus on symmetries related to matrices and vectors appearing in the simulation of quantum many-body systems. Spin Hamiltonians have special matrix-symmetry properties such as persymmetry. Furthermore, the systems may exhibit physical symmetries translating into symmetry properties of the eigenvectors of interest. Both types of symmetry can be exploited in sparse representation formats such as Matrix Product States (mps) for the desired eigenvectors. This paper summarizes symmetries of Hamiltonians for typical physical systems such as the Ising model and lists resulting properties of the related eigenvectors. Based on an overview of Matrix Product States (Tensor Trains or Tensor Chains) and their canonical normal forms we show how symmetry properties of the vector translate into relations between the mps matrices and, in turn, which symmetry properties result from relations within the MPS matrices. In this context we analyze different kinds of symmetries and derive appropriate normal forms for MPS representing these symmetries. Exploiting such symmetries by using these normal forms will lead to a reduction in the number of degrees of freedom in the MPS matrices. This paper provides a uniform platform for both well-known and new results which are presented from the (multi-)linear algebra point of view