Person:
Garay Elizondo, Luis Javier

First Name

Luis Javier

Last Name

Garay Elizondo

URI

https://hdl.handle.net/20.500.14352/75071

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Física Teórica

Area

Física Teórica

Identifiers

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Now showing 1 - 10 of 25

Quantum Gowdy model within the new loop quantum cosmology improved dynamics
(Journal of physics: Conference series, 2011) Martin- Benito, M.; Garay Elizondo, Luis Javier; Mena Marugán, Guillermo A.
The linearly polarized Gowdy T(3) model can be regarded as compact Bianchi I cosmologies with inhomogeneous modes allowed to travel in one direction. We study a hybrid quantization of this model that combines the loop quantization of the Bianchi I background, adopting the improved dynamics scheme put forward by Ashtekar and Wilson-Ewing, with a Fock quantization for the inhomogeneities. The Hamiltonian constraint operator provides a resolution of the cosmological singularity and superselects separable sectors. We analyze the complicated structure of these sectors. In any of them the Hamiltonian constraint provides an evolution equation with respect to the volume of the associated Bianchi I universe, with a well posed initial value problem. This fact allows us to construct the Hilbert space of physical states and to show that we recover the standard quantum field theory for the inhomogeneities.
Scale holography
(European physical journal C, 2018) Ruiz Cembranos, José Alberto; Ciarreta, Salvador E.R.; Garay Elizondo, Luis Javier
We present a new correspondence between a d-dimensional dynamical system and a family of higher-order derivative (d + 1)-dimensional systems. This new scaleholographic relation is built by the explicit introduction of a dimensionful constant which determines the size of the additional dimension. Scale holography is particularly useful for studying non-local theories, since the equivalent dual system on the higher dimensional manifold can be made to be local, as we illustrate with the specific examples of the p-adic string theory and the free particle.
The trans-Planckian problem as a guiding principle
(Journal of high energy physics, 2011) Barbado, L. C.; Barceló, C.; Garay Elizondo, Luis Javier; Jannes, Gil
We use the avoidance of the trans-Planckian problem of Hawking radiation as a guiding principle in searching for a compelling scenario for the evaporation of black holes or black-hole-like objects. We argue that there exist only three possible scenarios, depending on whether the classical notion of long-lived horizon is preserved by high-energy physics and on whether the dark and compact astrophysical objects that we observe have long-lived horizons in the first place. Along the way, we find that i) a theory with high-energy superluminal signalling and a long-lived trapping horizon would be extremely unstable in astrophysical terms and that i i) stellar pulsations of objects hovering right outside but extremely close to their gravitational radius can result in a mechanism for Hawking-like emission.
Hybrid classical-quantum formulations ask for hybrid notions
(Physical review A, 2012) Barceló, Carlos; Carballo- Rubio, Raúl; Garay Elizondo, Luis Javier; Gómez Escalante, Ricardo
We reappraise some of the hybrid classical-quantum models proposed in the literature with the goal of retrieving some of their common characteristics. In particular, first, we analyze in detail the Peres-Terno argument regarding the inconsistency of hybrid quantizations of the Sudarshan type. We show that to accept such hybrid formalism entails the necessity of dealing with additional degrees of freedom beyond those in the straight complete quantization of the system. Second, we recover a similar enlargement of degrees of freedom in the so-called statistical hybrid models. Finally, we use Wigner's quantization of a simple model to illustrate how in hybrid systems the subsystems are never purely classical or quantum. A certain degree of quantumness (classicality) is being exchanged between the different sectors of the theory, which in this particular unphysical toy model makes them undistinguishable.
Loop quantum cosmology of the Bianchi I model: complete quantization
(Journal of physics: Conference series, 2012) Martin Benito, M.; Garay Elizondo, Luis Javier; Mena Marugán, Guillermo A.; Wilson-Ewing, E.
We complete the canonical quantization of the vacuum Bianchi I model within the improved dynamics scheme of loop quantum cosmology, characterizing the Hilbert structure of the physical states and providing a complete set of observables acting on them. In order to achieve this task, it has been essential to determine the structure of the separable superselection sectors that arise owing to the polymeric quantization, and to prove that the initial value problem obtained when regarding the Hamiltonian constraint as an evolution equation, interpreting the volume as the evolution parameter, is well-posed.
Unveiling quantum entanglement degradation near a Schwarzschild black hole
(Physical review D, 2010) Martin Martinez, Eduardo; Garay Elizondo, Luis Javier; León, Juan
We analyze the entanglement degradation provoked by the Hawking effect in a bipartite system Alice-Rob when Rob is in the proximities of a Schwarzschild black hole while Alice is free falling into it. We will obtain the limit in which the tools imported from the Unruh entanglement degradation phenomenon can be used properly, keeping control on the approximation. As a result, we will be able to determine the degree of entanglement as a function of the distance of Rob to the event horizon, the mass of the black hole, and the frequency of Rob's entangled modes. By means of this analysis we will show that all the interesting phenomena occur in the vicinity of the event horizon and that the presence of event horizons do not effectively degrade the entanglement when Rob is far off the black hole. The universality of the phenomenon is presented: There are not fundamental differences for different masses when working in the natural unit system adapted to each black hole. We also discuss some aspects of the localization of Alice and Rob states. All this study is done without using the single mode approximation.
Hawking versus Unruh effects, or the difficulty of slowly crossing a black hole horizon
(Journal of High Energy Physics, 2016) Barbado, Luis C.; Barceló, Carlos; Garay Elizondo, Luis Javier; Jannes, Gil
When analyzing the perception of Hawking radiation by different observers, the Hawking effect becomes mixed with the Unruh effect. The separation of both effects is not always clear in the literature. Here we propose an inconsistency-free interpretation of what constitutes a Hawking effect and what an Unruh effect. An appropriate interpretation is important in order to elucidate what sort of effects a detector might experience depending on its trajectory and the state of the quantum field. Under simplifying assumptions we introduce an analytic formula that separates these two effects. Armed with the previous interpretation we argue that for a free-falling detector to cross the horizon without experiencing high-energy effects, it is necessary that the horizon crossing is not attempted at low velocities.
Project number: 34
Software libre como herramienta de aprendizaje en mecánica
(2018) Ruiz Cembranos, José Alberto; Villarrubia Rojo, Héctor; Llanes Estrada, Felipe José; Garay Elizondo, Luis Javier; López Maroto, Antonio; Fernández Sanz, David
Esta memoria contiene los principales resultados del proyecto de innovación docente número 34 de la convocatoria 2017/2018 que lleva por título "Software libre como herramienta de aprendizaje en mecánica".
Unruh Effect without Thermality
(Physical Review Letters, 2019) Carballo-Rubio, Raúl; Garay Elizondo, Luis Javier; Martín-Martínez, Eduardo; Ramón, José de
We show that uniformly accelerated detectors can display genuinely thermal features even if the Kubo-Martin-Schwinger (KMS) condition fails to hold. These features include satisfying thermal detailed balance and having a Planckian response identical to cases in which the KMS condition is satisfied. In this context, we discuss that satisfying the KMS condition for accelerated trajectories is just sufficient but not necessary for the Unruh effect to be present in a given quantum field theory. Furthermore, we extract the necessary and sufficient conditions for the response function of an accelerated detector to be thermal in the infinitely adiabatic limit. This analysis provides new insight about the interplay between the KMS condition and the Unruh effect, and a solid framework in which the robustness of the Unruh effect against deformations of quantum field theories (perhaps Lorentz-violating) can be answered unambiguously. © 2019 American Physical Society.
Two faces of quantum sound
(Physical review D, 2010) Barceló, C.; Garay Elizondo, Luis Javier; Jannes, G.
Fluctuations around a Bose-Einstein condensate can be described by means of Bogolubov theory leading to the notion of quasiparticle and antiquasiparticle familiar to nonrelativistic condensed-matter practitioners. On the other hand, we already know that these perturbations evolve according to a relativistic Klein-Gordon equation in the long-wavelength approximation. For shorter wavelengths, we show that this equation acquires nontrivial corrections which modify the Klein-Gordon product. In this approach, quasiparticles can also be defined (up to the standard ambiguities due to observer dependence). We demonstrate that-in the low-energy as well as in the high-energy regimes-both concepts of quasiparticle are actually the same, regardless of the formalism (Bogolubov or Klein-Gordon) used to describe them. These results also apply to any barotropic, inviscid, irrotational fluid, with or without quantum potential. Finally, we illustrate how the quantization of these systems of quasiparticles proceeds by analyzing a stationary configuration containing an acoustic horizon. We show that there are several possible choices of a regular vacuum state, including a regular generalization of the Boulware vacuum. Issues such us Hawking radiation crucially depend on this vacuum choice.