Enhancing quantum transduction via long-range waveguide mediated interactions between quantum emitters

Efficient transduction of electromagnetic signals between different frequency scales is an essential ingredient for modern communication technologies as well as for the emergent field of quantum information processing. Recent advances in waveguide photonics have enabled a breakthrough in light-matter coupling, where individual two-level emitters are strongly coupled to individual photons. Here we propose a scheme which exploits this coupling to boost the performance of transducers between low-frequency signals and optical fields operating at the level of individual photons. Specifically, we demonstrate how to engineer the interaction between quantum dots in waveguides to enable efficient transduction of electric fields coupled to quantum dots. Owing to the scalability and integrability of the solid-state platform, our transducer can potentially become a key building block of a quantum internet node. To demonstrate this, we show how it can be used as a coherent quantum interface between optical photons and a two-level system like a superconducting qubit.Comment: The maintext has 6 pages, two column and 4 figure

Shaping the future of hydraulic fracturing in the Canadian Arctic through environmental guidelines

yesThis paper addresses the regulation of energy resource projects on indigenous lands in the Canadian Arctic and the role of environmental impact assessment in these projects, specifically those involving hydraulic fracturing. Taking an environmental point of view, this paper argues that in the absence of specific territorial legislation applying to shale gas development in Nunavut and the onshore portion of the Inuvialuit Settlement Region in Northwest Territories the federal regulator, the National Energy Board, has a key role in promoting transparency, public participation, safety and sustainable use of natural resources. As part of its environmental protection responsibilities, the Board, inter alia, ensures that an environmental impact assessment is conducted before any proposed hydraulic fracturing activities commence on indigenous lands, which in some cases include an extensive public consultation. In 2013 the Board adopted rigorous guidelines for all onshore oil and gas projects involving hydraulic fracturing which address many of the concerns raised over shale gas development, including surface and groundwater contamination; impact on air quality; induced seismicity and reluctance of industry to disclose chemicals used in hydraulic fracturing. Although these guidelines are non-binding on the Board, their adoption means that it will be challenging for the operators to obtain an authorisation from the Board should they fail to conduct an environmental impact assessment. This paper argues that these guidelines exceed the best practices widely adopted by the Canadian shale gas industry. It concludes that because the guidelines address a number of concerns raised by the public they could potentially be used as the minimum standards for hydraulic fracturing operations in other regions outside Arctic Canada

Femtio års utveckling av försöken med sådd och plantering på Holmmyrbrännan i Västerbotten

På Holmmyrbrännan i Kulbäckslidens försökspark (64,2ºN, 295 m.ö.h.) anlades på 1960-talet 14 olika föryngringsförsök, bl.a. förbandsförsök och årsmånsförsök med tall och gran, risrensningsförsök och plantgödslingsförsök, försök för jämförelse av sådd och plantering, proveniensförsök med contortatall (Pinus contorta, Douglas) och demonstrationsförsök med cembratall (Pinus cembra, L.), klippgran (Abies lasiocarpa, Hooker) och sibirisk ädelgran (Abies sibirica, Ledeb.). Försöken var väldesignade och följdes med upprepade mätningar de första 15-20 åren. Några försök har återinventerats hösten 2011. Försöksverksamheten på Holmmyrbrännan sammanfattas i denna rapport. Ståndortsindex skattas med ståndortsbonitering till T21,8 m respektive G19,4 m och med höjdbonitering till 25 m för tall respektive 23 m för gran. I genomsnitt ligger överlevnaden 2011 mellan 40-50 % för tallen och 85-90 % för granen. Resultatet för tall kan synas nedslående men är normalt för Norrlands inland. Årsmånsförsöken uppvisar signifikanta och svårförklarade skillnader i överlevnad och tillväxt mellan årgångar. Tallkulturerna har skadats av älg, sork, snytbagge (Hylobius abietis, L.), rotmurkla (Rhizina undulate, Fr.), snöskytte (Phacidium infestans, Karst.), norrländsk tallkräfta (Lachnellula pini, Brunch.), gräsöverväxning och snöbelastning. Tallsådder som enkelställts 10 år efter sådd har nått lägre medelhöjder än tallplanteringar vid 20 års totalålder. Bästa contortatallsproveniens (latitud 51ºN) beräknas ha producerat 16 % högre volym än den lokala tallen till 48 års ålder. Sibirisk ädelgran beräknas ha producerat mer än den lokala granen. Tillförsel av fullgödsel vid planteringen har inte påverkat utvecklingen för vare sig tall eller gran, men ureagödsling av gran medförde ökad tidig plantavgång. För granplantering på obränd mark var avgångarna högre men höjdutvecklingen snabbare då plantering gjordes i mycket hyggesavfall, jämfört med plantering på risrensad mark. Granplantering i tätt förband på bränd mark visade tidigt tecken på stagnation (stavagranseffekt). Trots starkt urval av de växtligaste genom tidig röjning till glest förband fanns ingen signifikant produktionsskillnad jämfört med ursprunglig plantering i glest förband. En tendens fanns dock till högst produktion i den ursprungligen täta planteringen. Tallplanteringen runt försöken uppvisar samma låga överlevnad som försöksytorna. Den har ändå ansetts vara så jämn och välsluten att den lämpat sig för anläggning av ett omfattande gödslingsförsök

Semiconvergence and Relaxation Parameters for Projected SIRT Algorithms

We give a detailed study of the semiconvergence behavior of projected nonstationary simultaneous iterative reconstruction technique (SIRT) algorithms, including the projected Landweber algorithm. We also consider the use of a relaxation parameter strategy, proposed recently for the standard algorithms, for controlling the semiconvergence of the projected algorithms. We demonstrate the semiconvergence and the performance of our strategies by examples taken from tomographic imaging.Funding Agencies|Danish Research Council for Technology and Production Sciences|274-07-0065|</p

On some methods for entropy maximization and matrix scaling

AbstractWe describe and survey in this paper iterative algorithms for solving the discrete maximum entropy problem with linear equality constraints. This problem has applications e.g. in image reconstruction from projections, transportation planning, and matrix scaling. In particular we study local convergence and asymptotic rate of convergence as a function of the iteration parameter. For the trip distribution problem in transportation planning and the equivalent problem of scaling a positive matrix to achieve a priori given row and column sums, it is shown how the iteration parameters can be chosen in an optimal way. We also consider the related problem of finding a matrix X, diagonally similar to a given matrix, such that corresponding row and column norms in X are all equal. Reports of some numerical tests are given

How Robust is the Governance System of British Columbia for Regulating the Environmental Aspects of Shale Gas Development?

yesThis paper focuses on the robustness of the regulatory system of British Columbia (BC) from the environmental point of view. It argues that the enforcement of existing regulations is effective due to the active monitoring of compliance by the provincial oil and gas regulator. The regulator has a key role in promoting transparency, public participation and safety and sustainability of shale gas operations. The paper argues that although certain elements in the provincial legislative framework are covered by non-binding guidelines, rather than legislation, the regulator has responded to many of the concerns raised by the public over the shale gas development in BC, including impacts on regional air quality, fresh water contamination and access to water, deforestation, biodiversity and induced seismicity. The regulator has also recognized several key issues, such as baseline water monitoring as an issue requiring further research. This paper concludes that BC has one of the most robust regulatory systems in North America for regulating hydraulic fracturing

Prospective Governance and Legal Framework between the EU and MENA in Renewable Energy Cooperation

yesThis article provides an overview of the current stage of development as well as the outlook for future cooperation in the field of renewable energy between the European Union and the countries of Middle East and North Africa (MENA). To continue with the progress achieved in the context of the Mediterranean Solar Plan the MENA region should adopt a regionally coordinated approach due to the absence of an established institutional and regulatory framework for trans-regional cooperation. While several studies have highlighted the competitiveness of electricity produced from renewable energy sources in MENA, governments and policy makers in the region should carefully assess their ability to ensure a sustainable policy framework for the renewables sector and opportunities for trans-regional exchanges of electricity. This article proposes that in order to address governance issues and facilitate the creation of a regional energy market, MENA countries may need to adopt an intergovernmental instrument such as the Energy Charter Treaty or the International Energy Charter

Emerging Framework of Energy Governance in the MENA Region

yesThis paper sets out to provide a deeper understanding of the regulatory framework to drive energy transformation processes in the MENA region and the barriers for change. The recent developments in a global scale have encouraged States to look towards alternative sources of energy to power their nation, with nuclear energy and renewable technologies. Technologies such as wind power and solar energy appear to be attracting interest in many countries and regions, and in the MENA region this is primarily solar energy. However, all States are at different stages of development and therefore, it poses a challenge for taking into consideration definitively the costs and efficiency of renewable energy technologies. This paper investigates the state of preparedness of the legal framework in the region in order to deploy renewable sources of energy to power these countries in years to come