27,042 research outputs found
Extending the ADM formalism to Weyl geometry
In order to treat quantum cosmology in the framework of Weyl spacetimes we
take the first step of extending the Arnowitt-Deser-Misner formalism to Weyl
geometry. We then obtain an expression of the curvature tensor in terms of
spatial quantities by splitting spacetime in (3+1)-dimensional form. We next
write the Lagrangian of the gravitation field based in Weyl-type gravity
theory. We extend the general relativistic formalism in such a way that it can
be applied to investigate the quantum cosmology of models whose spacetimes are
endowed with a Weyl geometrical structure.Comment: 10 page
Scalable quantum memory in the ultrastrong coupling regime
Circuit quantum electrodynamics, consisting of superconducting artificial
atoms coupled to on-chip resonators, represents a prime candidate to implement
the scalable quantum computing architecture because of the presence of good
tunability and controllability. Furthermore, recent advances have pushed the
technology towards the ultrastrong coupling regime of light-matter interaction,
where the qubit-resonator coupling strength reaches a considerable fraction of
the resonator frequency. Here, we propose a qubit-resonator system operating in
that regime, as a quantum memory device and study the storage and retrieval of
quantum information in and from the Z2 parity-protected quantum memory, within
experimentally feasible schemes. We are also convinced that our proposal might
pave a way to realize a scalable quantum random-access memory due to its fast
storage and readout performances.Comment: We have updated the title, abstract and included a new section on the
open-system dynamic
Creation of quantum error correcting codes in the ultrastrong coupling regime
We propose to construct large quantum graph codes by means of superconducting
circuits working at the ultrastrong coupling regime. In this physical scenario,
we are able to create a cluster state between any pair of qubits within a
fraction of a nanosecond. To exemplify our proposal, creation of the five-qubit
and Steane codes is numerically simulated. We also provide optimal operating
conditions with which the graph codes can be realized with state-of-the-art
superconducting technologies.Comment: Added a new appendix sectio
Kinematic groups across the MW disc: insights from models and from the RAVE catalogue
With the advent of the Gaia data, the unprecedented kinematic census of great
part of the Milky Way disc will allow us to characterise the local kinematic
groups and new groups in different disc neighbourhoods. First, we show here
that the models predict a stellar kinematic response to the spiral arms and bar
strongly dependent on disc position. For example, we find that the kinematic
groups induced by the spiral arm models change significantly if one moves only
~ 0.6 kpc in galactocentric radius, but ~ 2 kpc in azimuth. There are more and
stronger groups as one approaches the spiral arms. Depending on the spiral
pattern speed, the kinematic imprints are more intense in nearby vicinities or
far from the Sun. Secondly, we present a preliminary study of the kinematic
groups observed by RAVE. This sample will allow us, for the first time, to
study the dependence on Galactic position of the (thin and thick) disc moving
groups. In the solar neighbourhood, we find the same kinematics groups as
detected in previous surveys, but now with better statistics and over a larger
spatial volume around the Sun. This indicates that these structures are indeed
large scale kinematic features.Comment: 4 pages, 3 figures, to appear in the proceedings of "Assembling the
Puzzle of the Milky Way", Le Grand Bornand (April 17-22, 2011), C. Reyle, A.
Robin, M. Schultheis (eds.
Phyllosilicate crystallinity in soils and weathering products from granitic rocks of Galicia
[Resumen] Se ha determinado la cristalinidad de micas y filosilicatos 1: 1 dioctaédricos de los
limos y arcillas de 20 perfiles edáficos desarrollados sobre rocas graníticas. Se observa una estrecha relación entre el valor del índice de cristalinidad de los filosilicatos 2: 1, el tipo de mica predominante en el material de partida y el grado de desarrollo de los suelos; la menor cristalinidad aparece asociada a suelos formados a partir de materiales en los que la biotita es la única mica presente o la predominante. Los estudios de D. R. X., A. T. D. e 1. R. coinciden en señalar el predominio de filosicitatos 1: 1 de muy débil organización interna, comprobándose por microscopía electrónica que son fundamentalmente de tipo halloysítico[Abstract] Micas and dioctaedric 1: 1 phyllosilicate crystallinity of loam and clay fractions of
twenty soil profiles developed from granite rocks have been determined. There are a clear relation among the cystallinity index of 2: 1 phyllosilicate, the prevailing type of mica in the soil-parent material and the soil evolution degree. Cystallinity is the lowest when soils are formed from granitic material when the most abundant mica is the biotite. XRD, DTA and RI studies indicate the predominance of very low ordered 1: 1 phyllosilicates, electron microscopy shows that they are mainly halloysitic anes
Micromorfological and mineralogical transformations in the weathering process of the Viveiro and Traba Granodiorites
[Resumen] Se realiza el estudio de dos perfiles de meteorizaci6n sobre granodioritas en Galicia (NW de España). El grado de drenaje condiciona la evolución de los feldespatos: en la saprolita de grano más grueso, con grandes fisuras, se transforman en gibbsita, en la de grano más fino este mineral aparece en las primeras etapas pero el producto final es halloysita. Las micas evolucionan en ambos casos hacia vermiculitas hidroxialumínicas.[Abstract] Two weathering profiles developed from granodiorites in Galicia (NW of Spain) are studied. The drainage degree determines the feldspars evolution. In the coarse grain saprolite, with great fissures, feldspars are transformed into gibbsite, while in the finer grain saprolite, the weathering product is halloysite. Micas change gradually to hidroxy-Al-interlayered vermiculite
Circular dichroism of cholesteric polymers and the orbital angular momentum of light
We explore experimentally if the light's orbital angular momentum (OAM)
interacts with chiral nematic polymer films. Specifically, we measure the
circular dichroism of such a material using light beams with different OAM. We
investigate the case of strongly focussed, non-paraxial light beams, where the
spatial and polarization degrees of freedom are coupled. Within the
experimental accuracy, we cannot find any influence of the OAM on the circular
dichroism of the cholesteric polymer.Comment: 3 pages, 4 figure
Inducing charges and currents from extra dimensions
In a particular variant of Kaluza-Klein theory, the so-called induced-matter
theory (IMT), it is shown that any configuration of matter may be geometrically
induced from a five-dimensional vacuum space. By using a similar approach we
show that any distribution of charges and currents may also be induced from a
five-dimensional vacuum space. Whereas in the case of IMT the geometry is
Riemannian and the fundamental equations are the five-dimensional Einstein
equations in vacuum, here we consider a Minkowskian geometry and the
five-dimensional Maxwell equations in vacuum.Comment: 8 pages. Accepted for publication in Modern Physics Letters
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