4 research outputs found
Analogue gravity and radial fluid flows: The case of AdS and its deformations
An analogue model for the spacetime has been recently
introduced by Mosna, Pitelli and Richartz [Phys. Rev. D 94, 104065 (2016)] by
considering sound waves propagating on a fluid with an ill-defined velocity
profile at its source/sink. The wave propagation is then uniquely defined only
when one imposes an extra boundary condition at the source/sink (which
corresponds to the spatial infinity of ). Here we show that, once
this velocity profile is smoothed out at the source/sink, the need for extra
boundary conditions disappears. This, in turn, corresponds to deformations of
the spacetime near its spatial infinity. We also examine how
this regularization of the velocity profile picks up a specific boundary
condition for the idealized system, so that both models agree in the long
wavelength limit.Comment: 6 pages, 3 figures. To appear in Phys Rev
Communication through quantum fields near a black hole
We study the quantum channel between two localized first-quantized systems
that communicate in 3+1 dimensional Schwarzschild spacetime via a quantum
field. We analyze the information carrying capacity of direct and black
hole-orbiting null geodesics as well as of the timelike contributions that
arise because the strong Huygens principle does not hold on the Schwarzschild
background. We find, in particular, that the non-direct-null and timelike
contributions, which do not possess an analog on Minkowski spacetime, can
dominate over the direct null contributions. We cover the cases of both
geodesic and accelerated emitters. Technically, we apply tools previously
designed for the study of wave propagation in curved spacetimes to a
relativistic quantum information communication setup, first for generic
spacetimes, and then for the case of Schwarzschild spacetime in particular.Comment: 38 pages (incl. 13 pages appendix), 14 figures, RevTeX 4.1. v3:
update to published versio
“Fantasmas” na mecânica quântica
CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCan you pick a complex subject in quantum mechanics and discuss it with a minimum number of equations, in a simplified form that the general scientific public could understand? This was a question presented to graduate students of the one-year Quantum Mechanics course based on the text book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano, at the State University of Campinas (UNICAMP), Brazil. The first seven authors of this paper are graduate students (alphabetical order) that accepted to try it. The chosen subject was "delocalized quantum states", and it will be discussed using colloquial terms like quantum ghosts, spooky action, splitting beings and invisibility cloak. © Sociedade Brasileira de Física. Printed in Brazil.Can you pick a complex subject in quantum mechanics and discuss it with a minimum number of equations, in a simplified form that the general scientific public could understand? This was a question presented to graduate students of the one-year Quantum Mechanics course based on the text book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano, at the State University of Campinas (UNICAMP), Brazil. The first seven authors of this paper are graduate students (alphabetical order) that accepted to try it. The chosen subject was "delocalized quantum states", and it will be discussed using colloquial terms like quantum ghosts, spooky action, splitting beings and invisibility cloak.383111CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOSem informaçãoSem informaçãoSem informaçãoPode-se escolher um topico complexo em mecanica quantica e discuti-lo com um numero mınimo de equações, e de forma simplificada para que um publico com apenas conhecimento basico em fısica possa entender? Essa foi a pergunta apresentada aos alunos de pos-graduação das disciplinas de um ano de Mecanica Quantica I e II da Universidade Estadual de Campinas (UNICAMP), baseadas no livro “Quantum Mechanics” de J. J. Sakurai e Jim Napolitano. Os primeiros sete autores desse artigosão os alunos de pos-graduação (em ordem alfabetica) que aceitaram o desafio. O topico escolhido foi estados quanticos delocalizados, e sera discutido utilizando termos coloquiais como fantasmas quanticos, ações fantasmagoricas, entidades divididas e capa de invisibilidade.G.M.A., D.T.M, M.M. and M.A.P.L acknowledge support from the Brazilian agency “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq). D.Q.A., L.F.M.C, and S.I.C.G acknowledge support from the Brazilian agency “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior” (CAPES), and L.F.C.F acknowledges support from the Brazilian state of São Paulo agency “Fundação de Amparo à Pesquisa do Estado de São Paulo” (FAPESP). The authors thank Amanda A. R. Lima for drawing the inspiring figure 2. The authors are grateful to Profs. Michael Brunger, Prof. Amir Caldeira and Prof. José A. Roversi for their critical reading of the manuscript and constructive comments and suggestions. The authors also thank for critical reading of this manuscript, the following group of people of the aimed public target: Paulo S. P. Lima (Mechanical Engineer), Martín E. Navarro Maldonado (Chemical Engineer), and Luis Quesada (Professor of Computer Science and Informatics)
Hadamard Tail from Initial Data on the Light Cone
Field perturbations of a curved background spacetime generally propagate not
only at the speed of light but also at all smaller velocities. This so-called
contribution to wave propagation is relevant in various
settings, from classical self-force calculations to communication between
quantum particle detectors. One method for calculating this tail contribution
is by integrating the homogeneous wave equation using Characteristic Initial
Data on the light cone. However, to the best of our knowledge, this method has
never been implemented before except in flat or conformally-flat spacetimes,
where null geodesics emanating from a point do not cross. In this work, we
implement this method on the black hole toy model Pleba\'nski-Hacyan spacetime,
. We obtain new results in this spacetime by
calculating the Hadamard tail of a scalar field everywhere where it is defined
(namely, in the maximal normal neighbourhood of an arbitrary point) and
investigate how it varies for various values of the coupling constant. This
serves as a proof-of-concept for the Characteristic Initial Data method on
spacetimes where null geodesics emanating from a point cross.Comment: 11 pages, 4 figure