151 research outputs found

    Lead-related quantum emitters in diamond

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    We report on quantum emission from Pb-related color centers in diamond following ion implantation and high-temperature vacuum annealing. First-principles calculations predict a negatively charged Pb-vacancy (PbV) center in a split-vacancy configuration, with a zero-phonon transition around 2.4 eV. Cryogenic photoluminescence measurements performed on emitters in nanofabricated pillars reveal several transitions, including a prominent doublet near 520 nm. The splitting of this doublet, 5.7 THz, exceeds that reported for other group-IV centers. These observations are consistent with the PbV center, which is expected to have a combination of narrow optical transitions and stable spin states, making it a promising system for quantum network nodes.U.S. Army Research Laboratory. Center for Distributed Quantum InformationNational Science Foundation (U.S.). Graduate Research Fellowship ProgramNational Science Foundation (U.S.) (Grant DMR-1231319)United States. National Aeronautics and Space Administration (Space Technology Research Fellowship)MIT-Harvard Center for Ultracold Atoms MIT International Science and Technology Initiativ

    Transform-limited photons from a coherent tin-vacancy spin in diamond

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    Solid-state quantum emitters that couple coherent optical transitions to long-lived spin qubits are essential for quantum networks. Here we report on the spin and optical properties of individual tin-vacancy (SnV) centers in diamond nanostructures. Through cryogenic magneto-optical and spin spectroscopy, we verify the inversion-symmetric electronic structure of the SnV, identify spin-conserving and spin-flipping transitions, characterize transition linewidths, measure electron spin lifetimes and evaluate the spin dephasing time. We find that the optical transitions are consistent with the radiative lifetime limit even in nanofabricated structures. The spin lifetime is phononlimited with an exponential temperature scaling leading to T1T_1 >> 10 ms, and the coherence time, T2T_2 reaches the nuclear spin-bath limit upon cooling to 2.9 K. These spin properties exceed those of other inversion-symmetric color centers for which similar values require millikelvin temperatures. With a combination of coherent optical transitions and long spin coherence without dilution refrigeration, the SnV is a promising candidate for feasable and scalable quantum networking applications

    Telecom networking with a diamond quantum memory

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    Practical quantum networks require interfacing quantum memories with existing channels and systems that operate in the telecom band. Here we demonstrate low-noise, bidirectional quantum frequency conversion that enables a solid-state quantum memory to directly interface with telecom-band systems. In particular, we demonstrate conversion of visible-band single photons emitted from a silicon-vacancy (SiV) center in diamond to the telecom O-band, maintaining low noise (g2(0)<0.1g^2(0)<0.1) and high indistinguishability (V=89±8%V=89\pm8\%). We further demonstrate the utility of this system for quantum networking by converting telecom-band time-bin pulses, sent across a lossy and noisy 50 km deployed fiber link, to the visible band and mapping their quantum states onto a diamond quantum memory with fidelity F=87±2.5%\mathcal{F}=87\pm 2.5 \% . These results demonstrate the viability of SiV quantum memories integrated with telecom-band systems for scalable quantum networking applications.Comment: 9 pages, 5 figures + Supplemental Material

    Education for sustainable development in higher education: evaluating coherence between theory and praxis

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    Universities are an important part of the process of change taking place in society. However, this is often overshadowed by these institutions giving priority to technocratic models in the relationship between science and society. In this context, according to Habermas, theories can serve to clarify practical questions and guide praxis into the right actions (social emancipation and rational autonomy). Habermas introduces the need to evaluate the particular contexts in which scientific arguments are made and assessed. The aim of this study was to develop a set of assessment criteria for education for sustainable development in higher education curricula. These were developed in line with Habermas by introducing further adaptions within the context of education for sustainable development. These criteria were tested in a blended learning master’s programme in Environmental Citizenship and Participation at the Universidade Aberta, Portugal. The following research tools were used as follows: (i) a questionnaire survey to the graduates; (ii) content analysis applied to the information guide and to the abstracts of the dissertations that were produced. The case study revealed that an absence of theoretical frameworks could lead to inconsistencies between theory and praxis. Improvements to curricula are then drawn from this study

    Blended versus face-to-face: comparing student performance in a therapeutics class

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    Therapeutics is a very complex subject for every pharmacy student, since it requires the application of knowledge from several other disciplines. The study of therapeutics is often done in case-based learning in order to promote reflective thinking and give a scenario as real as possible. The objective of this study was to compare student performance between faceto-face (n = 54) and blended learning (n = 56) approaches to the teaching of therapeutics. They can confirm that there are statistically significant differences (p < 0.05) between the final exam scores from both groups, being that the b learning group achieved higher scores. Blended learning seems to be an effective way to teach therapeutics, following pre established teaching methods, and above all, does not negatively affect student performance. It also provides new learning environments and strategies, and promotes the development of new skills such as learning and collaborating online, which may be relevant in a networked knowledge society.info:eu-repo/semantics/publishedVersio

    2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine

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    The writing committee conducted a comprehensive search of the medical and scientific literature through the use of PubMed/MEDLINE. Searches were limited to publications written in the English language. Compiled reports were reviewed and additional articles were provided by committee members. Specifically targeted searches were conducted on the following subtopics: acute aortic dissection, ankylosing spondylitis, aortic dissection and litigation, aortic neoplasm, aortic tumors, Behçet disease, bicuspid aortic valve, calcified aorta, chronic dissection, coarctation of the aorta, D-dimer, dissecting aneurysm, Ehlers-Danlos syndrome, endovascular and aortic aneurysms, medial degeneration, porcelain aorta, giant cell arteritis, imaging and thoracic aortic disease, inflammatory disease, intramural hematoma, Loeys-Dietz syndrome, Marfan syndrome, Noonan syndrome, penetrating aortic ulcer, polycystic kidney disease, thoracic and aortic aneurysms, thoracic aortic disease and patient care, thoracic aortic disease and surgery, thoracic aorta and Kawasaki disease, Takayasu arteritis, thoracoabdominal and aorta or aortic disease, and Turner syndrome. More than 850 references were reviewed, with 830 used as the primary evidence base for the final guideline. The ACCF/AHA Task Force on Practice Guidelines methodology processes were followed to write the text and recommendations. In general, published manuscripts appearing in journals listed in Index Medicus were used as the evidence base. Published abstracts were used only for emerging information but were not used in the formulation of recommendations
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