2,867 research outputs found
Localised projective measurement of a relativistic quantum field in non-inertial frames
We propose a scheme to study the effect of motion on measurements of a
quantum field carried out by a finite-size detector. We introduce a model of
projective detection of a localised field mode in an arbitrary reference frame.
We apply it to extract vacuum entanglement by a pair of counter-accelerating
detectors and to estimate the Unruh temperature of a single accelerated
detector. The introduced method allows us to directly relate the observed
effects with the instantaneous proper acceleration of the detector.Comment: 5 pages, 2 figures. v2 Significant increase in the detail level
regarding the motivation of the detector mode
The entangling side of the Unruh-Hawking effect
We show that the Unruh effect can create net quantum entanglement between
inertial and accelerated observers depending on the choice of the inertial
state. This striking result banishes the extended belief that the Unruh effect
can only destroy entanglement and furthermore provides a new and unexpected
source for finding experimental evidence of the Unruh and Hawking effects.Comment: 4 pages, 4 figures. Added Journal referenc
The time traveler's guide to the quantization of zero modes
We study the relationship between the quantization of a massless scalar field on the two-dimensional Einstein cylinder and in a spacetime with a time machine. We find that the latter picks out a unique prescription for the state of the zero mode in the Einstein cylinder. We show how this choice arises from the computation of the vacuum Wightman function and the vacuum renormalized stress-energy tensor in the time-machine geometry. Finally, we relate the previously proposed regularization of the zero mode state as a squeezed state with the time-machine warp parameter, thus demonstrating that the quantization in the latter regularizes the quantization in an Einstein cylinder
One- and two- dimensional models are equally effective inmonitoring the crust’s thermal response to advection bylarge-scale thrusting during orogenesis
Depto. de MineralogÃa y PetrologÃaFac. de Ciencias GeológicasTRUEpu
A general framework for nonholonomic mechanics: Nonholonomic Systems on Lie affgebroids
This paper presents a geometric description of Lagrangian and Hamiltonian
systems on Lie affgebroids subject to affine nonholonomic constraints. We
define the notion of nonholonomically constrained system, and characterize
regularity conditions that guarantee that the dynamics of the system can be
obtained as a suitable projection of the unconstrained dynamics. It is shown
that one can define an almost aff-Poisson bracket on the constraint AV-bundle,
which plays a prominent role in the description of nonholonomic dynamics.
Moreover, these developments give a general description of nonholonomic systems
and the unified treatment permits to study nonholonomic systems after or before
reduction in the same framework. Also, it is not necessary to distinguish
between linear or affine constraints and the methods are valid for explicitly
time-dependent systems.Comment: 50 page
Integral field spectroscopy of type-II QSOs at z=0.3-0.4
We present and analyse integral-field observations of six type-II QSOs with
z=0.3-0.4, selected from the Sloan Digital Sky Survey (SDSS). Two of our sample
are found to be surrounded by a nebula of warm ionized gas, with the largest
nebula extending across 8" (40 kpc). Some regions of the extended nebulae show
kinematics that are consistent with gravitational motion, while other regions
show relatively perturbed kinematics: velocity shifts and line widths too large
to be readily explained by gravitational motion. We propose that a ~20 kpc x20
kpc outflow is present in one of the galaxies. Possible mechanisms for
triggering the outflow are discussed. In this object, we also find evidence for
ionization both by shocks and the radiation field of the AGN.Comment: 6 pages, 5 figures, accepted by MNRAS Letter
Estrategia imperial y crédito local. El archipiélago de Malvinas en la construcción de la frontera hispánica (1767-1774)
This article investigates the role of the Malvinas/Falkland Islands in the reconfiguration of Hispanic American space since 1767. It articulates three variables of analysis: the geopolitical importance of the Malvinas/Falkland Islands on a global scale, their place in the redefinition of the Spanish monarchy’s imperial frontier, and the role played by the economic actors of the RÃo de la Plata in the colonization of the archipelago. Using political, cartographical and fiscal sources, this work demonstrates that the consolidation of borders —a necessity for the Monarchy— depended on a confluence of interests with local financial oligarchies.El presente artÃculo indaga el rol del archipiélago de Malvinas en la reconfiguración del espacio hispanoamericano desde 1767. Para ello, se articulan tres variables de análisis: la importancia geopolÃtica de las islas Malvinas a escala global, su lugar en la redefinición de la frontera imperial de la monarquÃa española, y el papel que los actores económicos del RÃo de la Plata tuvieron en la colonización del archipiélago. Empleando documentación polÃtica, cartográfica y fiscal, este trabajo demuestra que la consolidación de las fronteras que la MonarquÃa precisaba asegurar confluyó con los intereses de las oligarquÃas financieras locales
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