1,725 research outputs found

    New Cache Attacks and Defenses

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    The sharing of last-level cache (LLC) among different physical cores makes cache vulnerable to side channel attacks. An attacker can get private information about co-running applications (victims) by monitoring their accesses. Cache side channel attacks can be mitigated by partitioning cache between the victim and attacker. However, previous partition works make the incorrect assumption that only the victim's cache misses are visible to attackers. In this work, we provide the key insight that both cache hits and cache misses from the victim are vulnerable. For a cache hit, although it does not affect the existence state, it can still change the replacement state and coherence state, which can also leak information to attackers. Based on this, we propose Invisible-Victim cache (IVcache), a new cache design that can mitigate both traditional LLC attacks and the new variants. IVcache classifies all processes as protected and unprotected. For accesses from protected processes, IVcache handles state changes in a slightly different way to make those accesses absolutely invisible to any other processes. We evaluate the defense effectiveness and performance of IVcache in the gem5 simulator. We show that IVcache can defend against real-world attacks, and that it introduces negligible performance effect to both protected and unprotected processes

    Report of the Intergovernmental Committee of Experts on Sustainable Development Financing

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    In order to achieve the Millennium Development Goals (MDGs), substantial additional external funding needs to be mobilized. Estimates differ, but a 'ballpark' figure is an annual increase of US$50 billion. This could be achieved by a doubling of official development assistance (ODA). Welcome steps have been made in that direction, but this takes time, and time is of the essence. For this reason alone, it is necessary to consider new sources.In this policy brief, we consider seven new sources:* Global environmental taxes (carbon-use tax)* Tax on currency flows (the 'Tobin tax')* Creation of new Special Drawing Rights (SDRs)* International Finance Facility (IFF)* Increased private donations for development* Global lottery and global premium bond * Increased remittances from emigrants

    Agriculture and climate change: An agenda for negotiation in Copenhagen

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    Table of Contents: •Overview by Gerald C. Nelson •Agricultural Science and Technology Needs for Climate Change Adaptation and Mitigation by Rudy Rabbinge •Reducing Methane Emissions from Irrigated Rice by Reiner Wassmann, Yasukazu Hosen, and Kay Sumfleth •Direct and Indirect Mitigation Through Tree and Soil Management by Brent M. Swallow and Meine van Noordwijk •The Potential for Soil Carbon Sequestration by Rattan Lal •Mitigating Greenhouse Gas Emissions from Livestock Systems by M. Herrero and P. K. Thornton •The Role of Nutrient Management in Mitigation by Helen C. Flynn •Monitoring, Reporting, and Verification Methodologies for Agriculture, Forestry, and Other Land Use by Sean Smukler and Cheryl Palm •Synergies Among Mitigation, Adaptation, and Sustainable Development by Pete Smith •The Importance of Property Rights in Climate Change Mitigation by Helen Markelova and Ruth Meinzen-Dick •The Important Role of Extension Systems by Kristin E. Davis •Adaptation to Climate Change: Household Impacts and Institutional Responses by Futoshi Yamauchi and Agnes Quisumbing •The Constructive Role of International Trade by Franz FischlerClimate change, Copenhagen, Science and technology, rice, Soil fertility management, Greenhouse gas, Nutrients, Forestry resources, Land use, Sustainable development, International trade, extension activities, Household behavior, Institutional Impacts,

    Quantum memory protocols for photonic solid-state devices

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    A photonic quantum memory (QM) is a device that has the capability of storing a quantum state of light and retrieving back after a controlled time. It is an important element in quantum information science and is, among other applications, a crucial device for quantum repeater architectures which have been proposed to overcome the loss and the decoherence issues in long distance transmission of photons. Rare earth ion doped solid state systems are promising candidates for QMs which combine the advantages of solid state systems, such as scalability and reduced experimental complexity, with the long coherence time typically found in atomic systems. In this thesis, I investigated three different QM protocols in a Pr3+:Y2SiO5 crystal. The first part describes here the first demonstration of the spectral hole memory (SHoMe) protocol which was proposed theoretically in 2009. This protocol relies on slowing down the light in a long-lived spectral hole and transferring the excitations to the spin state. We first prepare a spectral hole, then send an input pulse whose bandwidth is comparable with the hole and stop the compressed light in the crystal by transferring the off-resonant coherence to the spin state with an optical p pulse. Later a second p pulse transfers the coherence back and leads to the emission of the stored light. We reached a storage and retrieval efficiency of around 40% in the classical regime, and of 31% in the single photon level, with a signal-to-noise ratio of 33 ± 4 for a mean input photon number of 1. These results demonstrate the most efficient and noiseless spin-wave solid-state optical memory at the single photon level to date. The second part of the thesis describes new experiments using the well-known atomic frequency comb (AFC) protocol. It is based on tailoring the inhomogeneously broadened absorption profile of the rare earth with periodic absorptive peaks, which induces the re-emission of the absorbed light field after a certain time determined by the separation between the peaks. In this chapter I describe several AFC experiments. First I present the storage of frequency converted telecom photons into our crystal where we obtained a total efficiency of 1.9 ± 0.2 % for a storage time of 1.6 µs storage time and signal-to-noise ratio of more than 200 for a mean input photon number of 1. Then I discuss the results of improved excited state storage efficiency values for long storage times where we achieved 30% at short storage times and up to 17% at 10 µs storage time. And finally I present a spin-wave AFC experiment where we obtained a signal-to-noise ratio value of 28 ± 8 for a mean input photon number of 1, the highest value achieved so far for this kind of experiment. Finally, in the last part, I describe the first demonstration of a solid-state photon pair source with embedded multimode quantum memory. The aim of the protocol is to combine a single photon source and a QM in one ensemble as in the well-known Duan-Lukin-Zoller-Cirac (DLCZ) scheme however this time not in a cold atomic ensemble but in a solid-state crystal. The protocol takes advantage of the AFC protocol for rephasing the ions and obtaining efficient read-out. The use of AFC also makes the protocol temporally multi-mode. In the experiment, after the AFC preparation we send an on-resonant write pulse and detect the decayed Stokes photons which herald single spin excitations. At a later time a read pulse transfers the spin excitation back to the excited state and we detect the anti-Stokes photons. We show strong non-classical second order cross-correlations between the Stokes and anti-Stokes photons and demonstrate storage of 11 temporal modes. The results presented in this thesis represent a significant contribution to the field of solid-state quantum memories and an important steps towards the realization of scalable quantum network architectures with solid state systems.Una memòria quàntica (MQ) és un dispositiu que té la capacitat d'emmagatzemar l'estat quàntic de la llum i retornar-lo després d'un temps controlat.És un element important en la ciència de la informació quàntica i és un dispositiu crucial per a arquitectures de repetidors quàntica.Els sistemes d'estat sòlid basats en ions de terres rares són candidats prometedors per implementar MQs, ja que combinen els avantatges dels sistemes sòlids (escalabilitat i poca complexitat experimental) amb els llargs temps de coherència dels sistemes atòmics.En aquesta tesis he investigat tres protocols diferents de MQ en un cristall de Pr3+:Y2SiO5. La primera part descriu la primera demostració del protocol de memòria basat en forats espectrals (MFE), que va ser proposat teòricament el 2009. Aquest protocol es basa en disminuir la velocitat de la llum en un forat espectral de vida llarga i transferir les excitacions a un estat d'espín. Comencem preparant un forat espectral, després enviem un pols de llum amb una amplada espectral comparable a la del forat i aturem la llum comprimida en el cristall transferint la coherència fora de ressonància a l'estat d'espín amb un pols òptic.Seguidament un segon pols retorna la coherència i porta a l'emissió de la llum emmagatzemada. Aconseguim una eficiència d'emmagatzematge i recuperació de 40% en el règim clàssic i de 31% al nivell de fotons individuals, amb una relació senyal-soroll de 33 ±4 per un nombre mitjà de fotons incidents igual a 1. Aquests resultats demostren la memòria òtica operant al nivell de fotons individuals amb més eficiència i més lliure de soroll. La segona part de la tesis descriu nous experiments que utilitzen el protocol de pintes de freqüència atòmiques (PFA). Aquest està basat en modificar el perfil d'absorció eixamplat inhomogèniament dels ions de terres rares, creant pics d'absorció periòdics que indueixen la reemissió del camp de llum absorbit, després d'un cert temps que ve determinat per la separació dels pics. En aquest capítol descric varis experiments de PFA. Primer presento l'emmagatzematge en el nostre cristall de fotons amb freqüència convertida des de telecom, obtenint una eficiència total de 1.9 ± 0.2% per un temps d'emmagatzematge de 1.6us i una relació senyal-soroll de més de 200 per un nombre mitjà de fotons incidents igual a 1. Seguidament discuteixo els resultats obtinguts amb una millorada eficiència d'emmagatzematge en l'estat excitat per temps d'emmagatzematge llargs, on vam obtenir 30% per temps curts i 17% a 10us. I finalment presento un experiment de PFA amb ona d'espín on vam obtenir una relació senyal-soroll de 28 ± 8 per un nombre mitjà de fotons incidents igual a 1, el valor més alt assolit mai en un experiment d'aquest tipus. Finalment, en la última part, descric la primera demostració d'una font de parelles de fotons d'estat sòlid integrada amb una memòria quàntica multimodal. L'objectiu del protocol és combinar en un sol sistema una font de fotons individuals i una MQ, com té lloc en el conegut esquema de Duan-Lukin-Cirac-Zoller (DLCZ), però en aquest cas amb un cristall en lloc d'un sistema d'àtoms freds.El protocol agafa els avantatges del protocol PFA per refasar els ions i obtenir una recuperació eficient. Utilitzant PFA fa que el protocol sigui temporalment multimodal.En l'experiment, després de la preparació de la PFA, enviem un pols d'escriptura en ressonància i detectem un fotó Stokes que anuncia excitacions d'espín individuals. Un temps més tard, un pols de lectura transfereix l'excitació d'espín de tornada cap a l'estat excitat i detectem fotons anti-Stokes. Mostrem fortes correlacions de segon ordre no-clàssiques entre els fotons de Stokes i anti-Stokes i demostrem l'emmagatzematge de 11 modes temporals. Els resultats presentats en aquesta tesis representen una contribució significativa en el camp de les memòries quàntiques d'estat sòlid i un pas important cap a la realització d'arquitectures de xarxes quàntiques amb sistemes d'estat sòlidPostprint (published version

    The Creation of a Climate Club for a Sustainable Economic Future: The Role of International Economic Law Amidst Geopolitical Confrontation

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    As of late July 2023, the month of July 2023 had become the hottest month ever recorded in history. Heads of the governments of small island states have been outspoken about the existential risk their countries face due to rising sea level as a consequence of climate change. Wildfires are more frequent and more negatively impactful than ever before in different parts of the world. It is no wonder that sustainability has become a buzz word in the media, and policymakers all over the world are, more than ever, focusing on trying to achieve a sustainable future. A sustainable global economy means providing good quality of life for everyone, keeping our planet clean and safe by tackling climate change, and having good-quality trading goods, such as agriculture, oil, and minerals. But how can the European Union (EU) and international law promote a highly sustainable global economy? How can EU countries and others ensure a sustainable global economy? This article has four sections. Section 1 proposes a climate club for a sustainable economic future. It challenges the view that trade’s only impact on the environment is negative. It takes the unconventional view that the trading system goes beyond benefiting the economy and society in that it can also contribute to environmental protection, with a specific focus on decarbonization. This section proposes a paradigm shift in how we approach trade and develops a new theory based on the triple benefit of trade—economic growth, climate change mitigation, and enhancement of energy security. This section incorporates the current trend of bottom-up, rather than top-down, solutions to today’s global challenges. It investigates how trade agreements may be more effective legal instruments than environmental agreements for environmental-protection purposes, a possibility that is both counter-intuitive and surprising, and identifies opportunities to promote sustainable energy and environmental protection in future trade agreements. Section 2 aims to explore the concept of a climate club linked to the international trade regime and proposes a strategy for its implementation the Group of Twenty (G20) framework. Section 2 examines the relevance of this proposal to Saudi Arabia, who is a member of the G20 and a participant in Mission Innovation. Saudi Arabia is one of the world’s largest oil producers and exporters, facing both opportunities and challenges in transitioning to a low-carbon economy. Saudi Arabia has expressed its commitment to diversifying its economy, reducing its dependence on oil revenues, and contributing to global efforts to combat climate change. However, Saudi Arabia also faces resistance from some of its trading partners who may perceive its climate policies as a threat to their energy security or competitiveness. Therefore, Saudi Arabia can benefit from joining a climate club that can provide it with access to new markets, technologies, and financing for its green transition. Section 3 analyzes the Saudi Green Initiative (SGI), launched by Saudi Arabia’s Crown Prince and Prime Minister Mohammed bin Salman in March of 2021.The SGI is a comprehensive plan to combat climate change and promote sustainable development. The initiative aims to reduce carbon emissions, increase the use of renewable energy, and protect natural resources in the Kingdom of Saudi Arabia. While the initiative has been praised for its ambitious goals, it has also faced criticism and skepticism from various quarters, which will be analyzed in Section 3. Section 4 explores the Saudi National Renewable Energy plan that is being implemented by the Saudi Government. This plan and the policy avenues mentioned in the previous paragraphs will be instrumental for a future EU trade law and policy in its bilateral relations with the Gulf Cooperation Council in the context of sustainability
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