Optical Holonomic Quantum Computer

In this paper the idea of holonomic quantum computation is realized within quantum optics. In a non-linear Kerr medium the degenerate states of laser beams are interpreted as qubits. Displacing devices, squeezing devices and interferometers provide the classical control parameter space where the adiabatic loops are performed. This results into logical gates acting on the states of the combined degenerate subspaces of the lasers, producing any one qubit rotations and interactions between any two qubits. Issues such as universality, complexity and scalability are addressed and several steps are taken towards the physical implementation of this model.Comment: 16 pages, 3 figures, REVTE

Перспективи використання тонкодисперсних вуглецевих матеріалів

У останні десятиліття особливу увагу вчених привертає дослідження різних алотропних видозмін вуглецю, зокрема природних: алмазу, графіту, лонсдейліту, фулерену, вуглецевих нанотрубок (у тому числі шунгіту – природного нанотехн-логічного матеріалу) і штучних: карбіну, графену, аморфного вуглецю (кокс, вугілля, технічний вуглець, сажа, активоване вугілля). Водночас у техніці все більше розповсюдження отримують тонкодисперсні вуглецеві матеріали, зокрема тонкодисперсне вугілля та технічний вуглець, тонкоподрібнений аморфний вуглець, активоване вугілля, дослідженню яких присвячено ряд окремих досліджень, у т.ч. і авторів статті

J/psi production and nuclear effects in p-Pb collisions at √sNN=5.02 TeV

Peer reviewe

Analytic representations based on SU(1,1) coherent states and their applications

We consider two analytic representations of the SU(1,1) Lie group: the representation in the unit disk based on the SU(1,1) Perelomov coherent states and the Barut-Girardello representation based on the eigenstates of the SU(1,1) lowering generator. We show that these representations are related through a Laplace transform. A ``weak'' resolution of the identity in terms of the Perelomov SU(1,1) coherent states is presented which is valid even when the Bargmann index $k$ is smaller than one half. Various applications of these results in the context of the two-photon realization of SU(1,1) in quantum optics are also discussed.Comment: LaTeX, 15 pages, no figures, to appear in J. Phys. A. More information on http://www.technion.ac.il/~brif/science.htm

Gendered endings: Narratives of male and female suicides in the South African Lowveld

This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s11013-012-9258-y. Copyright @ Springer Science+Business Media, LLC 2012.Durkheim’s classical theory of suicide rates being a negative index of social solidarity downplays the salience of gendered concerns in suicide. But gendered inequalities have had a negative impact: worldwide significantly more men than women perpetrate fatal suicides. Drawing on narratives of 52 fatal suicides in Bushbuckridge, South Africa, this article suggests that Bourdieu’s concepts of ‘symbolic violence’ and ‘masculine domination’ provide a more appropriate framework for understanding this paradox. I show that the thwarting of investments in dominant masculine positions have been the major precursor to suicides by men. Men tended to take their own lives as a means of escape. By contrast, women perpetrated suicide to protest against the miserable consequences of being dominated by men. However, contra the assumption of Bourdieu’s concept of ‘habitus’, the narrators of suicide stories did reflect critically upon gender constructs

Characterizing the morphology of the debris disk around the low-mass star GSC 07396-00759

Context. Debris disks have commonly been studied around intermediate-mass stars. Their intense radiation fields are believed to efficiently remove the small dust grains that are constantly replenished by collisions. For lower-mass stars, in particular M-stars, the dust removal mechanism needs to be further investigated given the much weaker radiation field produced by these objects. Aims. We present new polarimetric observations of the nearly edge-on disk around the pre-main sequence M-type star GSC 07396-00759, taken with VLT/SPHERE IRDIS, with the aim to better understand the morphology of the disk, its dust properties, and the star-disk interaction via the stellar mass-loss rate. Methods. We model our observations to characterize the location and properties of the dust grains using the Henyey-Greenstein approximation of the polarized phase function and evaluate the strength of the stellar winds. Results. We find that the observations are best described by an extended and highly inclined disk (i\approx 84.3\,^{\circ}\pm0.3) with a dust distribution centered at a radius $r_{0}\approx107\pm2$ au. The polarized phase function $S_{12}$ is best reproduced by an anisotropic scattering factor $g\approx0.6$ and small micron-sized dust grains with sizes $s>0.3\,\mathrm{\mu}$m. We furthermore discuss some of the caveats of the approach and a degeneracy between the grain size and the porosity. Conclusions. Even though the radius of the disk may be over-estimated, our results suggest that using a given scattering theory might not be sufficient to fully explain key aspects such as the shape of the phase function, or the dust grain size. With the caveats in mind, we find that the average mass-loss rate of GSC 07396-00759 can be up to 500 times stronger than that of the Sun, supporting the idea that stellar winds from low-mass stars can evacuate small dust grains from the disk

Circumstellar discs: What will be next?

This prospective chapter gives our view on the evolution of the study of circumstellar discs within the next 20 years from both observational and theoretical sides. We first present the expected improvements in our knowledge of protoplanetary discs as for their masses, sizes, chemistry, the presence of planets as well as the evolutionary processes shaping these discs. We then explore the older debris disc stage and explain what will be learnt concerning their birth, the intrinsic links between these discs and planets, the hot dust and the gas detected around main sequence stars as well as discs around white dwarfs.Comment: invited review; comments welcome (32 pages

High power conical-shaped Niobium targets for reliable [18F-] production and lower [18O] water consumption: High power conical-shaped Niobium targets for reliable [18F-] production and lower [18O] water consumption

Introduction In order to address the increasing demand for Fluorine-18 and the rising cost per mL of 18O enriched water, IBA developed improvements to their 18F- production systems. For this new design we started from scratch, with the main objectives of reducing the required enriched water volume and improving the cooling of the insert. A better cooling allows increasing the target current and thus the produced activity. Finally, we aimed to reduce the number of parts and improve the design of auxiliary components. Material and Methods Six Niobium conical inserts with different target chamber volumes were machined and tested. Only 4 of these were selected to create the new range of IBA 18F− targets shown in TABLE 1. The new Niobium target inserts have a complex shape with drilled channels on the outside of the chamber and a deep channel next to the beam strike area (FIG. 1, green circle) to ensure efficient cooling. The 18O water inlet lines are now directly inserted in the Niobium body (FIG. 1, blue circle) to improve 18F- quality (no more contact with small o-rings). In operation, a 35µm Havar® target window is used. All tests were performed using IBA Cyclone® 18 cyclotron. The targets were filled with different volumes of enriched 18O water (enrichment > 92 %) and irradiated with 18 MeV protons on target with beam currents up to 145 μA for 30 to 150 minutes, while the internal pressure rise of the target was recorded. For each target, a pressure-current curve was plotted and an optimum balance between target water fill volume, pressure and current has been determined, which maximises available activity after two hours, in each case. Results and Conclusion Radionuclidic impurities were measured and more than 100 FDG syntheses on various synthesizers confirmed the effectiveness of the new design. Increasing the current up to 145µA in Conical 16, the production reached 18 Ci in 2 hours, single beam, with a target pressure under 43 bar. Today, the use of these new targets for daily commercial production is increasing within the IBA Cyclone® installed base