177,432 research outputs found
Design of microcavity resonators for single-atom detection
No full textWhispering gallery modes of a microdisk resonator are useful for the optical detection of single rubidium and cesium atoms near the surface of a substrate. Light is coupled into two high-Q whispering-gallery modes of the disk which can provide attractive and/or repulsive potentials, respectively, via their evanescent fields. The sum potential, including van der Waals/Casimir-Polder surface forces, may be tuned to exhibit a minimum at distances on the order of 100nm from the disk surface. Simultaneously optically trapping and detecting is possible, with the back-action of an atom held in this trap on the light fields being sufficiently strong to provide a measurable effect. Atom trapping and detection depend on a variety of system parameters and experimental realizations differ for different atoms
Size effect in waveguide coupled whispering gallery mode disk resonators
No full textWe investigate the bound and evanescent fields of the optical whispering gallery modes which are supported by a toroid microcavity and which may be used for a wide range of applications. Results of simulations using finite-difference time domain solutions of Maxwell's equations are compared with semi-analytical solutions based on coupled mode theory. Key parameters such as resonance frequencies, transmittance characteristics, coupling efficiencies, and bending/scattering losses are analyzed as a function of experimental variables such as size, distance, and fabrication roughness. Finally, the feasibility of single-atom detection is discussed
Michel Folman, Introduction à l'étude de la sculpture archaïsante grecque et gréco-romaine, 1935
No full textDemangel R. Michel Folman, Introduction à l'étude de la sculpture archaïsante grecque et gréco-romaine, 1935. In: Revue des Études Anciennes. Tome 37, 1935, n°4. p. 480
Michel Folman, Introduction à l'étude de la sculpture archaïsante grecque et gréco-romaine, 1935
No full textDemangel R. Michel Folman, Introduction à l'étude de la sculpture archaïsante grecque et gréco-romaine, 1935. In: Revue des Études Anciennes. Tome 37, 1935, n°4. p. 480
High-Q micro-resonators for trapping and detecting a single atom on a chip
No full textRecent progress in the manufacturing of high Q dielectric microresonant structures enables their use as photonic devices that can manipulate and/or detect single atoms on a nanometer scale. Of specific interest is the wafer-based manufacturing of resonators where a good control of the physical characteristics can be achieved during fabrication and during operation, while at the same time allowing integration with other functions on the chip. We also discuss experimental feasibility and compare with first experiments in the field
Single-atom detection using whispering gallery modes of microdisk resonators
No full textWe investigate the possibility of using dielectric microdisk resonators for the optical detection of single atoms trapped and cooled in magnetic microtraps near the surface of a substrate. The bound and evanescent fields of optical whispering-gallery modes are calculated and the coupling to straight waveguides is investigated using finite-difference time domain solutions of Maxwell's equations. Results are compared with semianalytical solutions based on coupled mode theory. We discuss atom detection efficiencies and the feasibility of nondestructive measurements in such a system depending on key parameters such as disk size, disk-waveguide coupling, and scattering losses
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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