A very brief introduction to quantum computing and quantum information theory for mathematicians

This is a very brief introduction to quantum computing and quantum information theory, primarily aimed at geometers. Beyond basic definitions and examples, I emphasize aspects of interest to geometers, especially connections with asymptotic representation theory. Proofs of most statements can be found in standard references

Quantitative MRFM characterization of the autonomous and forced dynamics in a spin transfer nano-oscillator

Using a magnetic resonance force microscope (MRFM), the power emitted by a spin transfer nano-oscillator consisting of a normally magnetized Py$|$Cu$|$Py circular nanopillar is measured both in the autonomous and forced regimes. From the power behavior in the subcritical region of the autonomous dynamics, one obtains a quantitative measurement of the threshold current and of the noise level. Their field dependence directly yields both the spin torque efficiency acting on the thin layer and the nature of the mode which first auto-oscillates: the lowest energy, spatially most uniform spin-wave mode. From the MRFM behavior in the forced dynamics, it is then demonstrated that in order to phase-lock this auto-oscillating mode, the external source must have the same spatial symmetry as the mode profile, i.e., a uniform microwave field must be used rather than a microwave current flowing through the nanopillar

Semileptonic charm decays D \to \pi l \nu_{\l} and D→KlνlD \to K l \nu_l from QCD Light-Cone Sum Rules

We present a new calculation of the $D\to\pi$ and $D \to K$ form factors from QCD light-cone sum rules. The $\overline{MS}$ scheme for the $c$-quark mass is used and the input parameters are updated. The results are $f^+_{D\pi}(0)= 0.67^{+0.10}_{-0.07}$, $f^+_{DK}(0)=0.75^{+0.11}_{-0.08}$ and $f^+_{D\pi}(0)/f^+_{DK}(0)=0.88 \pm 0.05$. Combining the calculated form factors with the latest CLEO data, we obtain $|V_{cd}|=0.225\pm 0.005 \pm 0.003 ^{+0.016}_{-0.012}$ and $|V_{cd}|/|V_{cs}|= 0.236\pm 0.006\pm 0.003\pm 0.013$ where the first and second errors are of experimental origin and the third error is due to the estimated uncertainties of our calculation. We also evaluate the form factors $f^-_{D\pi}$ and $f^-_{DK}$ and predict the slope parameters at $q^2=0$. Furthermore, calculating the form factors from the sum rules at $q^2<0$, we fit them to various parameterizations. After analytic continuation, the shape of the $D\to \pi,K$ form factors in the whole semileptonic region is reproduced, in a good agreement with experiment.Comment: 34 pages, 5 figure

Persistence of characteristics of an ordered flux line lattice above the second peak in Bi2Sr2CaCu2O8+δBi_2Sr_2CaCu_2O_{8+ \delta}

We report Small Angle Neutron Scattering measurements of the flux lines lattice (FLL) in $Bi_2Sr_2CaCu_2O_{8+ \delta}$. As previously reported, the scattered intensity decreases strongly when the magnetic field is increased, but it remains measurable far above the second peak. The direct observation of Bragg peaks proves that the characteristics of a lattice are still present. No structural features related to a symmetry breaking, such as a liquid like or an amorphous state, can be observed. However, the associated scattered intensity is very low and is difficult to explain. We discuss the coexistence between two FLL states as a possible interpretation.Comment: accepted for publication in Phys Rev

Form Factors and Strong Couplings of Heavy Baryons from QCD Light-Cone Sum Rules

We derive QCD light-cone sum rules for the hadronic matrix elements of the heavy baryon transitions to nucleon. In the correlation functions the $\Lambda_c,\Sigma_c$ and $\Lambda_b$ -baryons are interpolated by three-quark currents and the nucleon distribution amplitudes are used. To eliminate the contributions of negative parity heavy baryons, we combine the sum rules obtained from different kinematical structures. The results are then less sensitive to the choice of the interpolating current. We predict the $\Lambda_{b}\to p$ form factor and calculate the widths of the $\Lambda_{b}\to p\ell\nu_l$ and $\Lambda_{b}\to p \pi$ decays. Furthermore, we consider double dispersion relations for the same correlation functions and derive the light-cone sum rules for the $\Lambda_cND^{(*)}$ and $\Sigma_cND^{(*)}$ strong couplings. Their predicted values can be used in the models of charm production in $p\bar{p}$ collisions.Comment: 45 pages, 3 figure

Current Productions Carnuntum, German Limes and Radiopast

[EN] The here presented three chosen projects mark out different techniques of production and their transmission of content. The differentiated impact on the public absorption of the transported content are described dependent to experiences with it in exhibitions and publications, and can be used to rectify future approaches of similar topics. In most of these productions, technical difficulties were observed and solved through extensive use of different tools and techniques to achieve a reasonable output and represent our current state of knowledge which we would like to share. The documentation of the production as well as the communication between the production and research team is indispensable to the sucsess of these media formats.[ES] Presento tres proyectos elegidos que delimitan técnicas diferentes de la producción y su transmisión de contenido. El impacto diferenciado en la absorción pública del contenido es descrito dependiente a experiencias con ello en exposiciones y publicaciones, y puede ser usado para rectificar futuros acercamientos de temas similares. En la mayor parte de estas producciones, las dificultades técnicas fueron estudiadas y solucionadas por el uso extenso de instrumentos diferentes y técnicas para conseguir una salida razonable y representar nuestro estado del conocimiento que nos gustaría compartir. La documentación de la producción así como la comunicación entre la producción y grupo de investigación es indispensable en estos formatos multimedia.The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007- 2013) under grant agreement n° 230679, under the action Marie Curie – People IAPP, with the Project entitled “Radiography of the past. Integrated non-destructive approaches to understand and valorise complex archaeological sitesHumer, F.; Gugl, C.; Pregesbauer, M.; Vermeulen, F.; Corsi, C.; Klein, M. (2011). Current Productions Carnuntum, German Limes and Radiopast. Virtual Archaeology Review. 2(4):131-137. https://doi.org/10.4995/var.2011.4569OJS13113724CORSI C., DE DAPPER M., DE PREZ S., VERMEULEN F. (2005). Geoarchaeological observations on the Roman town of Ammaia, Internet Archaeology 19.CORSI C., VERMEULEN F. (2007). Elementi per la ricostruzione del paesaggio urbano e suburbano della città romana di Ammaia in Lusitania, Lusitania, Archeologia Aerea 3: 13-30.DEPREZ S., DE DAPPER M. & DE JAEGER C. (2006), The water supply of the Roman town of Ammaia (Northeastern Alentejo, Portugal): a geoarchaeological case study, Publicações da Associação Portuguesa de Geomorfólogos 3: 109-133.MANTAS V. (2000). A sociedade luso-romano do município de Ammaia, in: Gorges J.-G. & Nogales Basarrate T. (Eds.), Sociedad y cultura en Lusitania romana, Mérida, Museo Nacional de Arte Romano: 391-420.http://www.carnuntum.co.at/ , http://www.carnuntum-db.at/, http://www.limes.co.at/, http://7reasons.at/http://www.limeswelten.net/, http://www.arctron.de/, http://7reasons.at

Star-shaped Local Density of States around Vortices in a Type II Superconductor

The electronic structure of vortices in a type II superconductor is analyzed within the quasi-classical Eilenberger framework. The possible origin of a sixfold ``star'' shape of the local density of states, observed by scanning tunneling microscope experiments on NbSe$_2$, is examined in the light of the three effects; the anisotropic pairing, the vortex lattice, and the anisotropic density of states at the Fermi surface. Outstanding features of split parallel rays of this star are well explained in terms of an anisotropic $s$-wave pairing. This reveals a rich internal electronic structure associated with a vortex core.Comment: 4 pages, REVTeX, 3 figures available upon reques