Articles de revues : « Gravity-Decoherence »

1

Kiefer, Claus. « Topology, decoherence, and semiclassical gravity ». Physical Review D 47, n^o 12 (15 juin 1993) : 5414–21. http://dx.doi.org/10.1103/physrevd.47.5414.

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Podolskiy, Dmitriy, et Robert Lanza. « On decoherence in quantum gravity ». Annalen der Physik 528, n^o 9-10 (26 septembre 2016) : 663–76. http://dx.doi.org/10.1002/andp.201600011.

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Mavromatos, Nick E. « CPT Violation and decoherence in quantum gravity ». Journal of Physics : Conference Series 171 (1 juin 2009) : 012007. http://dx.doi.org/10.1088/1742-6596/171/1/012007.

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Anastopoulos, C., et B. L. Hu. « Decoherence in quantum gravity : issues and critiques ». Journal of Physics : Conference Series 67 (1 mai 2007) : 012012. http://dx.doi.org/10.1088/1742-6596/67/1/012012.

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5

Kiefer, Claus. « Decoherence in quantum electrodynamics and quantum gravity ». Physical Review D 46, n^o 4 (15 août 1992) : 1658–70. http://dx.doi.org/10.1103/physrevd.46.1658.

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Das, Saurya, Matthew P. G. Robbins et Elias C. Vagenas. « Gravitation as a source of decoherence ». International Journal of Modern Physics D 27, n^o 02 (janvier 2018) : 1850008. http://dx.doi.org/10.1142/s0218271818500086.

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It is believed that classical behavior emerges in a quantum system due to decoherence. It has also been proposed that gravity can be a source of this decoherence. We examine this in detail by studying a number of quantum systems, including ultrarelativistic and nonrelativistic particles, at low and high temperatures in an expanding universe, and show that this proposal is valid for a large class of quantum systems.

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Rijavec, Simone, Matteo Carlesso, Angelo Bassi, Vlatko Vedral et Chiara Marletto. « Decoherence effects in non-classicality tests of gravity ». New Journal of Physics 23, n^o 4 (1 avril 2021) : 043040. http://dx.doi.org/10.1088/1367-2630/abf3eb.

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Hu, B. L. « Gravitational decoherence, alternative quantum theories and semiclassical gravity ». Journal of Physics : Conference Series 504 (14 avril 2014) : 012021. http://dx.doi.org/10.1088/1742-6596/504/1/012021.

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Samuel, Joseph. « Gravity and decoherence : the double slit experiment revisited ». Classical and Quantum Gravity 35, n^o 4 (15 janvier 2018) : 045004. http://dx.doi.org/10.1088/1361-6382/aaa313.

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Gambini, Rodolfo, Rafael A. Porto et Jorge Pullin. « Fundamental decoherence from quantum gravity : a pedagogical review ». General Relativity and Gravitation 39, n^o 8 (11 juillet 2007) : 1143–56. http://dx.doi.org/10.1007/s10714-007-0451-1.

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Bera, Sayantani, Sandro Donadi, Kinjalk Lochan et Tejinder P. Singh. « A Comparison Between Models of Gravity Induced Decoherence ». Foundations of Physics 45, n^o 12 (14 juillet 2015) : 1537–60. http://dx.doi.org/10.1007/s10701-015-9933-2.

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Illuminati, Fabrizio, Gaetano Lambiase et Luciano Petruzziello. « Neutrino Dynamics in a Quantum-Corrected Schwarzschild Spacetime ». Universe 8, n^o 4 (24 mars 2022) : 202. http://dx.doi.org/10.3390/universe8040202.

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We study neutrino propagation in a curved spacetime background described by the Schwarzschild solution with the addition of quantum corrections evaluated in the framework of perturbative quantum gravity at lowest order. In particular, we investigate neutrino oscillations and decoherence within the Gaussian wave packet description, finding that quantum gravity corrections significantly affect the intrinsic features of mixed particles and induce potentially measurable physical effects.

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Luciano, Giuseppe Gaetano, et Massimo Blasone. « Gravitational Effects on Neutrino Decoherence in the Lense–Thirring Metric ». Universe 7, n^o 11 (1 novembre 2021) : 417. http://dx.doi.org/10.3390/universe7110417.

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We analyze the effects of gravity on neutrino wave packet decoherence. As a specific example, we consider the gravitational field of a spinning spherical body described by the Lense–Thirring metric. By working in the weak-field limit and employing Gaussian wave packets, we show that the characteristic coherence length of neutrino oscillation processes is nontrivially affected, with the corrections being dependent on the mass and angular velocity of the gravity source. Possible experimental implications are finally discussed.

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Diósi, Lajos. « The gravity-related decoherence master equation from hybrid dynamics ». Journal of Physics : Conference Series 306 (8 juillet 2011) : 012006. http://dx.doi.org/10.1088/1742-6596/306/1/012006.

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Kay, Bernard S. « Decoherence of macroscopic closed systems within Newtonian quantum gravity ». Classical and Quantum Gravity 15, n^o 12 (1 décembre 1998) : L89—L98. http://dx.doi.org/10.1088/0264-9381/15/12/003.

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Shushi, Tomer. « Randomness in modified general relativity theory : The stochastic f(R) gravity model ». Canadian Journal of Physics 96, n^o 11 (novembre 2018) : 1173–77. http://dx.doi.org/10.1139/cjp-2017-0938.

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We consider a stochastic modification of the f(R) gravity models, and provide its important properties, including the gravity field equations for the model. We show a prediction in which particles are localized by a system of random gravitational potentials. As an important special case, we investigate a gravity model in the presence of a small stochastic space–time perturbation and provide its gravity field equations. Using the proposed model we examine the stochastic quantum mechanics interpretation, and obtain a novel Schrödinger equation with gravitational potential that is based on diffusion in a gravitational field. Furthermore, we provide a new interpretation to the wavefunction collapse. It seems that the stochastic f(R) gravity model causes decoherence of the spatial superposition state of particles.

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Maimone, Filippo, Adele Naddeo et Giovanni Scelza. « Interaction between Everett Worlds and Fundamental Decoherence in Non-Unitary Newtonian Gravity ». Universe 9, n^o 3 (27 février 2023) : 121. http://dx.doi.org/10.3390/universe9030121.

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It is shown that the non-unitary Newtonian gravity (NNG) model admits a simple interpretation in terms of the Feynman path integral, in which the sum over all possible histories is replaced by a summation over pairs of paths. Correlations between different paths are allowed by a fundamental decoherence mechanism of gravitational origin and can be interpreted as a kind of communication between different branches of the wave function. The ensuing formulation could be used in turn as a motivation to introduce non-unitary gravity itself.

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SONG, Jianlan. « Disproval of Gravity-induced Quantum Decoherence by Micius in Space ». Bulletin of the Chinese Academy of Sciences 34, n^o 1 (1 janvier 2020) : 16–17. http://dx.doi.org/10.3724/sp.j.7101866521.

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Joshi, Siddarth Koduru, Jacques Pienaar, Timothy C. Ralph, Luigi Cacciapuoti, Will McCutcheon, John Rarity, Dirk Giggenbach et al. « Space QUEST mission proposal : experimentally testing decoherence due to gravity ». New Journal of Physics 20, n^o 6 (12 juin 2018) : 063016. http://dx.doi.org/10.1088/1367-2630/aac58b.

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Cherkas, Sergey, et Vladimir Kalashnikov. « Æther as an Inevitable Consequence of Quantum Gravity ». Universe 8, n^o 12 (28 novembre 2022) : 626. http://dx.doi.org/10.3390/universe8120626.

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The fact that quantum gravity does not admit an invariant vacuum state has far-reaching consequences for all physics. It points out that space could not be empty, and we return to the notion of an æther. Such a concept requires a preferred reference frame for describing universe expansion and black holes. Here, we intend to find a reference system or class of metrics that could be attributed to “æther”. We discuss a vacuum and quantum gravity from three essential viewpoints: universe expansion, black hole existence, and quantum decoherence.

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Amelino-Camelia, Giovanni. « Classicality, Matter–Antimatter Asymmetry, and Quantum Gravity Deformed Uncertainty Relations ». Modern Physics Letters A 12, n^o 19 (21 juin 1997) : 1387–92. http://dx.doi.org/10.1142/s0217732397001412.

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Some of the recent work on quantum gravity has involved modified uncertainty relations such that the products of the uncertainties of certain pairs of observables increase with time. It is here observed that this type of modified uncertainty relations would lead to quantum decoherence, which could explain the classical behavior of macroscopic systems, and CPT-violation, which could provide the seed for the emergence of a matter–antimatter asymmetry.

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LOMBARDO, FERNANDO C., MARIO A. CASTAGNINO et LUCA BOMBELLI. « FROM CLASSICAL CHAOS TO DECOHERENCE IN ROBERTSON–WALKER COSMOLOGY ». Modern Physics Letters A 14, n^o 07 (7 mars 1999) : 539–47. http://dx.doi.org/10.1142/s0217732399000596.

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We analyze the relationship between classical chaos and particle creation in Robertson–Walker cosmological models with gravity coupled with a scalar field. Within our class of models chaos and particle production are seen to arise in the same cases. Particle production is viewed as the seed of decoherence, which enables the quantum to classical transition and ensures that the correspondence between the quantum and classically chaotic models will be valid.

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23

Kiefer, Claus. « Emergence of a classical Universe from quantum gravity and cosmology ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 370, n^o 1975 (28 septembre 2012) : 4566–75. http://dx.doi.org/10.1098/rsta.2011.0492.

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I describe how we can understand the classical appearance of our world from a universal quantum theory. The essential ingredient is the process of decoherence. I start with a general discussion in ordinary quantum theory and then turn to quantum gravity and quantum cosmology. There is a whole hierarchy of classicality from the global gravitational field to the fluctuations in the cosmic microwave background, which serve as the seeds for the structure in the Universe.

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Feller, Alexandre, et Etera R. Livine. « Surface state decoherence in loop quantum gravity, a first toy model ». Classical and Quantum Gravity 34, n^o 4 (20 janvier 2017) : 045004. http://dx.doi.org/10.1088/1361-6382/aa525c.

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Diósi, Lajos. « Notes on certain Newton gravity mechanisms of wavefunction localization and decoherence ». Journal of Physics A : Mathematical and Theoretical 40, n^o 12 (7 mars 2007) : 2989–95. http://dx.doi.org/10.1088/1751-8113/40/12/s07.

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Bera, S., S. Donadi, K. Lochan et TP Singh. « A comparison between models of gravity induced decoherence of the wavefunction ». Journal of Physics : Conference Series 626 (3 juillet 2015) : 012040. http://dx.doi.org/10.1088/1742-6596/626/1/012040.

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27

Castagnino, M. A., A. Gangui, F. D. Mazzitelli et I. I. Tkachev. « Third quantization, decoherence and the interpretation of quantum gravity in minisuperspace ». Classical and Quantum Gravity 10, n^o 12 (1 décembre 1993) : 2495–504. http://dx.doi.org/10.1088/0264-9381/10/12/008.

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Crull, Elise M. « Less Interpretation and More Decoherence in Quantum Gravity and Inflationary Cosmology ». Foundations of Physics 45, n^o 9 (14 novembre 2014) : 1019–45. http://dx.doi.org/10.1007/s10701-014-9847-4.

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Benatti, F., R. Floreanini, S. Olivares et E. Sindici. « Noisy effects in interferometric quantum gravity tests ». International Journal of Quantum Information 15, n^o 08 (décembre 2017) : 1740014. http://dx.doi.org/10.1142/s0219749917400147.

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Quantum-enhanced metrology is boosting interferometer sensitivities to extraordinary levels, up to the point where table-top experiments have been proposed to measure Planck-scale effects predicted by quantum gravity theories. In setups involving multiple photon interferometers, as those for measuring the so-called holographic fluctuations, entanglement provides substantial improvements in sensitivity. Entanglement is however a fragile resource and may be endangered by decoherence phenomena. We analyze how noisy effects arising either from the weak coupling to an external environment or from the modification of the canonical commutation relations in photon propagation may affect this entanglement-enhanced gain in sensitivity.

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Addazi, Andrea. « Topological Portals from Matter to Antimatter ». Symmetry 14, n^o 3 (8 mars 2022) : 551. http://dx.doi.org/10.3390/sym14030551.

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We discuss possibilities of generating a Majorana mass for the neutron from topological quantum gravity effects which survive at mesoscopic scales from decoherence. We show how virtual micro-black hole (BH) pairs with skyrme/baryon hairs induce a neutron–antineutron transition which can be tested in next generation of experiments. Such effects do not destabilize the proton. We also discuss how BHs with mix ordinary and mirror baryon hairs can mediate neutron-mirror neutron mixings.

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Okon, Elias, et Daniel Sudarsky. « Less Decoherence and More Coherence in Quantum Gravity, Inflationary Cosmology and Elsewhere ». Foundations of Physics 46, n^o 7 (5 mai 2016) : 852–79. http://dx.doi.org/10.1007/s10701-016-0007-x.

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Arzano, Michele. « Decoherence and discrete symmetries in deformed relativistic kinematics ». EPJ Web of Conferences 166 (2018) : 00008. http://dx.doi.org/10.1051/epjconf/201816600008.

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Models of deformed Poincaré symmetries based on group valued momenta have long been studied as effective modifications of relativistic kinematics possibly capturing quantum gravity effects. In this contribution we show how they naturally lead to a generalized quantum time evolution of the type proposed to model fundamental decoherence for quantum systems in the presence of an evaporating black hole. The same structures which determine such generalized evolution also lead to a modification of the action of discrete symmetries and of the CPT operator. These features can in principle be used to put phenomenological constraints on models of deformed relativistic symmetries using precision measurements of neutral kaons.

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GAMBINI, RODOLFO, RAFAEL A. PORTO et JORGE PULLIN. « NO BLACK HOLE INFORMATION PUZZLE IN A RELATIONAL UNIVERSE ». International Journal of Modern Physics D 13, n^o 10 (décembre 2004) : 2315–20. http://dx.doi.org/10.1142/s0218271804006383.

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The introduction of a relational time in quantum gravity naturally implies that pure quantum states evolve into mixed quantum states. We show, using a recently proposed concrete implementation, that the rate at which pure states naturally evolve into mixed ones is faster than that due to collapsing into a black hole that later evaporates. This is rather remarkable since the fundamental mechanism for decoherence is usually very weak. Therefore the "black hole information puzzle" is rendered de-facto unobservable.

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Miller, Jonathan, et Roman Pasechnik. « Quasi-Classical Gravity Effect on Neutrino Oscillations in a Gravitational Field of a Heavy Astrophysical Object ». Advances in High Energy Physics 2015 (2015) : 1–15. http://dx.doi.org/10.1155/2015/381569.

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In the framework of quantum field theory, a graviton interacts locally with a quantum state having definite mass, that is, the gravitational mass eigenstate, while a weak boson interacts with a state having definite flavor, that is, the flavor eigenstate. An interaction of a neutrino with an energetic graviton may trigger the collapse of the neutrino to a definite mass eigenstate with probability expressed in terms of PMNS mixing matrix elements. Thus, gravitons would induce quantum decoherence of a coherent neutrino flavor state similarly to how weak bosons induce quantum decoherence of a neutrino in a definite mass state. We demonstrate that such an essentially quantum gravity effect may have strong consequences for neutrino oscillation phenomena in astrophysics due to relatively large scattering cross sections of relativistic neutrinos undergoing large angle radiation of energetic gravitons in gravitational field of a classical massive source (i.e., the quasi-classical case of gravitational Bethe-Heitler scattering). This graviton-induceddecoherenceis compared todecoherencedue to propagation in the presence of the Earth matter effect. Based on this study, we propose a new technique for the indirect detection of energetic gravitons by measuring the flavor composition of astrophysical neutrinos.

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Vergeles, S. N. « Dynamical method for quantizing gravity and the problem of decoherence in quantum cosmology ». Journal of Experimental and Theoretical Physics 91, n^o 5 (novembre 2000) : 859–72. http://dx.doi.org/10.1134/1.1334977.

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Di Domenico, Antonio. « Testing CPT Symmetry with Neutral K Mesons : A Review ». Symmetry 12, n^o 12 (11 décembre 2020) : 2063. http://dx.doi.org/10.3390/sym12122063.

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The neutral kaon system is a very peculiar system that offers unique possibilities to perform precise tests of the CPT symmetry. The entanglement of neutral kaon pairs that are produced at a ϕ-factory opens up new ways and scenarios in order to test this fundamental discrete symmetry. In this paper, the results of the most recent and significant CPT tests are reviewed. Experiments have set stringent limits on the CPT-violating parameters of different phenomenological models, some of them associated to possible decoherence mechanisms or Lorentz symmetry violation which might be justified in a quantum gravity framework. The present results show no violation of CPT symmetry, while their accuracy in some cases reaches the interesting level at which–in the most optimistic scenarios–quantum gravity effects might show up.

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Matsumura, Akira. « Role of matter coherence in entanglement due to gravity ». Quantum 6 (11 octobre 2022) : 832. http://dx.doi.org/10.22331/q-2022-10-11-832.

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We investigate the quantum nature of gravity in terms of the coherence of quantum objects. As a basic setting, we consider two gravitating objects each in a superposition state of two paths. The evolution of objects is described by the completely positive and trace-preserving (CPTP) map with a population-preserving property. This property reflects that the probability of objects being on each path is preserved. We use the ℓ1-norm of coherence to quantify the coherence of objects. In the present paper, the quantum nature of gravity is characterized by an entangling map, which is a CPTP map with the capacity to create entanglement. We introduce the entangling-map witness as an observable to test whether a given map is entangling. We show that, whenever the gravitating objects initially have a finite amount of the ℓ1-norm of coherence, the witness tests the entangling map due to gravity. Interestingly, we find that the witness can test such a quantum nature of gravity, even when the objects do not get entangled. This means that the coherence of gravitating objects always becomes the source of the entangling map due to gravity. We further discuss a decoherence effect and an experimental perspective in the present approach.

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Giesel, Kristina, et Michael Kobler. « An Open Scattering Model in Polymerized Quantum Mechanics ». Mathematics 10, n^o 22 (13 novembre 2022) : 4248. http://dx.doi.org/10.3390/math10224248.

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We derive a quantum master equation in the context of a polymerized open quantum mechanical system for the scattering of a Brownian particle in an ideal gas environment. The model is formulated in a top-down approach by choosing a Hamiltonian with a coupling between the system and environment that is generally associated with spatial decoherence. We extend the existing work on such models by using a non-standard representation of the canonical commutation relations, inspired by the quantization procedure applied in loop quantum gravity, which yields a model in which position operators are replaced by holonomies. The derivation of the master equation in a top-down approach opens up the possibility to investigate in detail whether the assumptions, usually used in such models in order to obtain a tractable form of the dissipator, hold also in the polymerized case or whether they need to be dropped or modified. Furthermore, we discuss some physical properties of the master equation associated to effective equations for the expectation values of the fundamental operators and compare our results to the already existing models of collisional decoherence.

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Sakharov, Alexander, Nick Mavromatos, Anselmo Meregaglia, André Rubbia et Sarben Sarkar. « Exploration of possible quantum gravity effects with neutrinos I : Decoherence in neutrino oscillations experiments ». Journal of Physics : Conference Series 171 (1 juin 2009) : 012038. http://dx.doi.org/10.1088/1742-6596/171/1/012038.

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KOPF, TOMÁŠ. « SPECTRAL GEOMETRY AND CAUSALITY ». International Journal of Modern Physics A 13, n^o 15 (20 juin 1998) : 2693–708. http://dx.doi.org/10.1142/s0217751x98001360.

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For a physical interpretation of a theory of quantum gravity, it is necessary to recover classical space–time, at least approximately. However, quantum gravity may eventually provide classical space–times by giving spectral data similar to those appearing in noncommutative geometry, rather than by giving directly a space–time manifold. It is shown that a globally hyperbolic Lorentzian manifold can be given by spectral data. A new phenomenon in the context of spectral geometry is observed: causal relationships. The employment of the causal relationships of spectral data is shown to lead to a highly efficient description of Lorentzian manifolds, indicating the possible usefulness of this approach. Connections to free quantum field theory are discussed for both motivation and physical interpretation. It is conjectured that the necessary spectral data can be generically obtained from an effective field theory having the fundamental structures of generalized quantum mechanics: a decoherence functional and a choice of histories.

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Chiarelli, Piero. « The Spinor-Tensor Gravity of the Classical Dirac Field ». Symmetry 12, n^o 7 (6 juillet 2020) : 1124. http://dx.doi.org/10.3390/sym12071124.

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In this work, with the help of the quantum hydrodynamic formalism, the gravitational equation associated with the classical Dirac field is derived. The hydrodynamic representation of the Dirac equation described by the evolution of four mass densities, subject to the theory-defined quantum potential, has been generalized to the curved space-time in the covariant form. Thence, the metric of space-time has been defined by imposing the minimum action principle. The derived gravity shows the spontaneous emergence of the “cosmological” gravity tensor (CGT), a generalization of the classical cosmological constant (CC), as a part of the energy-impulse tensor density (EITD). Even if the classical cosmological constant is set to zero, the CGT is non-zero, allowing a stable quantum vacuum (out of the collapsed branched polymer phase). The theory shows that in the classical macroscopic limit, the general relativity equation is recovered. In the perturbative approach, the CGT leads to a second-order correction to Newtonian gravity that takes contribution from the space where the mass is localized (and the space-time is curvilinear), while it tends to zero as the space-time approaches the flat vacuum, leading, as a means, to an overall cosmological constant that may possibly be compatible with the astronomical observations. The Dirac field gravity shows analogies with the modified Brans–Dicke gravity, where each spinor term brings an effective gravity constant G divided by its field squared. The work shows that in order to obtain the classical minimum action principle and the general relativity limit of the macroscopic classical scale, quantum decoherence is necessary.

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Mavromatos, Nick E. « Models & ; Searches of CPT Violation : a personal, very partial, list ». EPJ Web of Conferences 166 (2018) : 00005. http://dx.doi.org/10.1051/epjconf/201816600005.

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In this talk, first I motivate theoretically, and then I review the phenomenology of, some models entailing CPT Violation (CPTV). The latter is argued to be responsible for the observed matter-antimatter asymmetry in the Cosmos, and may owe its origin to either Lorentz-violating background geometries, whose effects are strong in early epochs of the Universe but very weak today, being temperature dependent in general, or to an ill-defined CPT generator in some quantum gravity models entailing decoherence of quantum matter as a result of quantum degrees of freedom in the gravity sector that are inaccessible to the low-energy observers. In particular, for the latter category of CPTV, I argue that entangled states of neutral mesons (Kaons or B-systems), of central relevance to KLOE-2 experiment, can provide smoking-gun sensitive tests or even falsify some of these models. If CPT is ill-defined one may also encounter violations of the spin-statistics theorem, with possible consequences for the Pauli Exclusion Principle, which I only briefly touch upon.

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AHLUWALIA, D. V. « AMBIGUITY IN SOURCE FLUX OF COSMIC/ASTROPHYSICAL NEUTRINOS : EFFECTS OF BI-MAXIMAL MIXING AND QUANTUM-GRAVITY INDUCED DECOHERENCE ». Modern Physics Letters A 16, n^o 14 (10 mai 2001) : 917–25. http://dx.doi.org/10.1142/s0217732301003760.

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For high energy cosmic neutrinos Athar, Jeźabek, and Yasuda (AJY) have recently shown that the existing data on neutrino oscillations suggest that cosmic neutrino flux at the AGN/GRB source, F(νe):F(νμ):F(ντ) ≈ 1:2:0, oscillates to F(νe):F(νμ):F(ντ) ≈ 1:1:1. These results can be confirmed at AMANDA, Baikal, ANTARES and NESTOR, and other neutrino detectors with a good flavor resolution. Here, we rederive the AJY result from quasi bi-maximal mixing, and show that observation of F(νe):F(νμ):F(ντ) ≈ 1:1:1 does not necessarily establish cosmic neutrino flux at the AGN/GRB source to be F(νe):F(νμ):F(ντ) ≈ 1:2:0. We also note that if the length scale for the quantum-gravity induced decoherence for astrophysical neutrinos is of the order of a Mpc, then independent of the MNS matrix, the Liu–Hu–Ge (LHG) mechanism would lead to flux equalization for the cosmic/astrophysical neutrinos.

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Gambini, Rodolfo, Rafael A. Porto et Jorge Pullin. « A relational solution to the problem of time in quantum mechanics and quantum gravity : a fundamental mechanism for quantum decoherence ». New Journal of Physics 6 (14 avril 2004) : 45. http://dx.doi.org/10.1088/1367-2630/6/1/045.

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Xiang, Xia, Jiankang Chen, Hui Wang, Liang Pei et Zhenyu Wu. « PS Selection Method for and Application to GB-SAR Monitoring of Dam Deformation ». Advances in Civil Engineering 2019 (7 décembre 2019) : 1–15. http://dx.doi.org/10.1155/2019/8320351.

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Ground-based synthetic aperture radar (GB-SAR) is a relatively new technique that can be used to monitor the deformation of large-volume targets, such as dams, slopes, and bridges. In this study, the permanent scatterer (PS) technique is used to address the issues encountered in the continuous monitoring of the external deformation of an arch-gravity dam in a hydraulic and hydropower engineering structure in Hubei, China; the technique includes large image data sizes, high accuracy requirements, a susceptibility of the monitoring data to atmospheric disturbances, complex phase unwrapping, and pronounced decoherence. Through an in-depth investigation of PS extraction methods, a combined PS selection (CPSS) method is proposed by fully taking advantage of the signal amplitude and phase information in the monitored scene. The principle and implementation of CPSS are primarily studied. In addition, preliminarily selected PS candidates are directly used to construct and update a triangular irregular network (TIN) to maintain the stability of the subsequent Delaunay TIN. To implement this method, a differential-phase standard-deviation threshold method is proposed to extract PSs that are highly spatially coherent and consistent. Finally, the proposed CPSS was applied to the safety monitoring of the dam. The monitoring results are compared with conventional inverted plumb line monitoring results, and the proposed CPSS is found to be effective and reliable.

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Kauffman, Stuart A. « Quantum Gravity If Non-Locality Is Fundamental ». Entropy 24, n^o 4 (15 avril 2022) : 554. http://dx.doi.org/10.3390/e24040554.

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I take non-locality to be the Michelson–Morley experiment of the early 21st century, assume its universal validity, and try to derive its consequences. Spacetime, with its locality, cannot be fundamental, but must somehow be emergent from entangled coherent quantum variables and their behaviors. There are, then, two immediate consequences: (i). if we start with non-locality, we need not explain non-locality. We must instead explain an emergence of locality and spacetime. (ii). There can be no emergence of spacetime without matter. These propositions flatly contradict General Relativity, which is foundationally local, can be formulated without matter, and in which there is no “emergence” of spacetime. If these be true, then quantum gravity cannot be a minor alteration of General Relativity but must demand its deep reformulation. This will almost inevitably lead to: matter not only curves spacetime, but “creates” spacetime. We will see independent grounds for the assertion that matter both curves and creates spacetime that may invite a new union of quantum gravity and General Relativity. This quantum creation of spacetime consists of: (i) fully non-local entangled coherent quantum variables. (ii) The onset of locality via decoherence. (iii) A metric in Hilbert space among entangled quantum variables by the sub-additive von Neumann entropy between pairs of variables. (iv) Mapping from metric distances in Hilbert space to metric distances in classical spacetime by episodic actualization events. (v) Discrete spacetime is the relations among these discrete actualization events. (vi) “Now” is the shared moment of actualization of one among the entangled variables when the amplitudes of the remaining entangled variables change instantaneously. (vii) The discrete, successive, episodic, irreversible actualization events constitute a quantum arrow of time. (viii) The arrow of time history of these events is recorded in the very structure of the spacetime constructed. (ix) Actual Time is a succession of two or more actual events. The theory inevitably yields a UV cutoff of a new type. The cutoff is a phase transition between continuous spacetime before the transition and discontinuous spacetime beyond the phase transition. This quantum creation of spacetime modifies General Relativity and may account for Dark Energy, Dark Matter, and the possible elimination of the singularities of General Relativity. Relations to Causal Set Theory, faithful Lorentzian manifolds, and past and future light cones joined at “Actual Now” are discussed. Possible observational and experimental tests based on: (i). the existence of Sub- Planckian photons, (ii). knee and ankle discontinuities in the high-energy gamma ray spectrum, and (iii). possible experiments to detect a creation of spacetime in the Casimir system are discussed. A quantum actualization enhancement of repulsive Casimir effect would be anti-gravitational and of possible practical use. The ideas and concepts discussed here are not yet a theory, but at most the start of a framework that may be useful.

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CAMACHO, A. « ON A QUANTUM EQUIVALENCE PRINCIPLE ». Modern Physics Letters A 14, n^o 04 (10 février 1999) : 275–88. http://dx.doi.org/10.1142/s0217732399000328.

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The logical consistency of a description of quantum theory in the context of general relativity, which includes minimal coupling principle, is analyzed from the point of view of Feynman's formulation in terms of path integrals. We will argue from this standpoint and use an argument that claims the incompleteness of the general relativistic description of gravitation, which emerges as a consequence of the gravitationally induced phases of the so-called flavor-oscillation clocks, that the postulates of quantum theory are logically incompatible with the usual minimal coupling principle. It will be shown that this inconsistency could emerge from the fact that the required geometrical information to calculate the probability of finding a particle at any point of the respective manifold does not lie in a region with finite volume. Then we put forth a new quantum minimal coupling principle in terms of a restricted path integral, and along the ideas of this model not only the propagator of a free particle is calculated but also the conditions under which we recover Feynman's case for a free particle are deduced. The effect on diatomic interstellar molecules is also calculated. The already existing relation between restricted path integral formalism and decoherence model will enable us to connect the issue of a quantum minimal coupling principle with the collapse of the wave function. From this last remark we will claim that the geometrical structure of the involved manifold acts as, always present, a measuring device on a quantum particle. In other words, in this proposal we connect the issue of a quantum minimal coupling principle with a claim which states that gravity could be one of the physical entities which results in the collapse of the wave function.

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Xu, Ping, Yiqiu Ma, Ji-Gang Ren, Hai-Lin Yong, Timothy C. Ralph, Sheng-Kai Liao, Juan Yin et al. « Satellite testing of a gravitationally induced quantum decoherence model ». Science 366, n^o 6461 (19 septembre 2019) : 132–35. http://dx.doi.org/10.1126/science.aay5820.

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Quantum mechanics and the general theory of relativity are two pillars of modern physics. However, a coherent unified framework of the two theories remains an open problem. Attempts to quantize general relativity have led to many rival models of quantum gravity, which, however, generally lack experimental foundations. We report a quantum optical experimental test of event formalism of quantum fields, a theory that attempts to present a coherent description of quantum fields in exotic spacetimes containing closed timelike curves and ordinary spacetime. We experimentally test a prediction of the theory with the quantum satellite Micius that a pair of time-energy–entangled particles probabilistically decorrelate passing through different regions of the gravitational potential of Earth. Our measurement results are consistent with the standard quantum theory and hence do not support the prediction of event formalism.

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Gambini, Rodolfo, Rafael A. Porto et Jorge Pullin. « Fundamental decoherence in quantum gravity ». Brazilian Journal of Physics 35, n^o 2a (juin 2005). http://dx.doi.org/10.1590/s0103-97332005000200010.

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Schimmoller, Alex J., Gerard McCaul, Hartmut Abele et Denys I. Bondar. « Decoherence-free entropic gravity : Model and experimental tests ». Physical Review Research 3, n^o 3 (19 juillet 2021). http://dx.doi.org/10.1103/physrevresearch.3.033065.

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