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We propose a fully covariant model for smeared particle detectors in quantum field theory in curved spacetimes. We show how effects related to accelerated motion of the detector and the curvature of spacetime influence the way different…

Quantum Physics · Physics 2020-06-26 Eduardo Martín-Martínez , T. Rick Perche , Bruno de S. L. Torres

Assuming that Quantum Mechanics is universal and that it can be applied over all scales, then the Universe is allowed to be in a quantum superposition of states, where each of them can correspond to a different space-time geometry. How can…

General Relativity and Quantum Cosmology · Physics 2024-02-27 José Luis Gaona-Reyes , Lucía Menéndez-Pidal , Mir Faizal , Matteo Carlesso

We give a review of UV renormalization of Ho\v{r}ava gravity (HG) models introduced as a remedy against violation of unitarity in quantum gravity theory. Projectable and non-projectable low-dimensional HG models and the spectra of their…

High Energy Physics - Theory · Physics 2023-02-07 Andrei O. Barvinsky

Quasifree states of a linear Klein-Gordon quantum field on globally hyperbolic spacetime manifolds are considered. Using techniques from the theory of pseudodifferential operators and wavefront sets on manifolds a criterion for a state to…

High Energy Physics - Theory · Physics 2007-05-23 Wolfgang Junker

We discuss the semiclassical limit of Quantum Reduced Loop Gravity, a recently proposed model to address the quantum dynamics of the early Universe. We apply the techniques developed in full Loop Quantum Gravity to define the semiclassical…

General Relativity and Quantum Cosmology · Physics 2015-06-18 Emanuele Alesci , Francesco Cianfrani

In this study, we propose a generalized pseudoclassical theory for the kicked rotor model in an attempt to discern the footprints of the classical dynamics in the deep quantum regime. Compared with the previous pseudoclassical theory that…

Quantum Physics · Physics 2024-01-30 Zhixing Zou , Jiao Wang

The quantum-reduced loop-gravity technique has been introduced for dealing with cosmological models. We show that it can be applied rather generically: anytime the spatial metric can be gauge-fixed to a diagonal form. The technique selects…

General Relativity and Quantum Cosmology · Physics 2013-11-13 Emanuele Alesci , Francesco Cianfrani , Carlo Rovelli

A gravity-induced approach to wavefunction collapse based on semiclassical gravity is enhanced by the hypothesis of a temporally expanding spacetime, which leads to a collapse model that can resolve the conflict between quantum nonlocality…

Quantum Physics · Physics 2022-12-21 Garrelt Quandt-Wiese

General covariance is a crucial notion in the study of field theories in curved spacetime. A field theory defined with respect to a semi-Riemannian metric is generally covariant if two metrics which are related by a diffeomorphism produce…

Mathematical Physics · Physics 2023-02-21 Filip Dul

The global time is defined in covariant form under the condition of a constant mean curvature slicing of spacetime. The background static metric is taken in the tangent space. The global intrinsic time is identified with the logarithmic…

General Relativity and Quantum Cosmology · Physics 2018-04-23 A. B. Arbuzov , A. E. Pavlov

We argue, in light of Collapse Model interpretation of quantum theory, that the fundamental division between the quantum and classical behaviors is analogous to the division of thermodynamic phases. A specific relationship between the…

Quantum Physics · Physics 2023-08-08 Fernanda Torres , Sujoy K. Modak , Alfredo Aranda

Let $X$ be a smooth projective variety over an algebraically closed field of arbitrary characteristic, and $f$ a dynamical correspondence of $X$. In 2016, the second author conjectured that the dynamical degrees of $f$ defined by the…

Algebraic Geometry · Mathematics 2021-12-01 Fei Hu , Tuyen Trung Truong

A new model is proposed for the purpose of modelling the ``wave function collapse'' of a two-state quantum system. The collapse to a classical state is driven by a nonlinear evolution equation with an extreme sensitivity to absolute phase.…

Quantum Physics · Physics 2007-05-23 H. Brusheim-Johansson , J. Hansson

We study a class of dynamical systems modelled as Markov chains that admit an invariant distribution via the corresponding transfer, or Koopman, operator. While data-driven algorithms to reconstruct such operators are well known, their…

Machine Learning · Computer Science 2022-12-14 Vladimir Kostic , Pietro Novelli , Andreas Maurer , Carlo Ciliberto , Lorenzo Rosasco , Massimiliano Pontil

Canonical methods can be used to construct effective actions from deformed covariance algebras, as implied by quantum-geometry corrections of loop quantum gravity. To this end, classical constructions are extended systematically to…

General Relativity and Quantum Cosmology · Physics 2013-05-30 Martin Bojowald , George M. Paily

Simulation of quantum dynamics is a grand challenge of computational physics. In this work we investigate methods for reducing the demands of such simulation by identifying reduced-order models for dynamics generated by parameterized…

Quantum Physics · Physics 2014-12-15 Akshat Kumar , Mohan Sarovar

We investigate a large class of gravity theories that respect spatial covariance, and involve kinetic terms for both the spatial metric and the lapse function. Generally such kind of theories propagate four degrees of freedom, one of which…

General Relativity and Quantum Cosmology · Physics 2019-05-16 Xian Gao , Zhi-Bang Yao

Effective models of black holes interior have led to several proposals for regular black holes. In the so-called polymer models, based on effective deformations of the phase space of spherically symmetric general relativity in vacuum, one…

General Relativity and Quantum Cosmology · Physics 2020-03-11 Denis Arruga , Jibril Ben Achour , Karim Noui

We perform a covariant constraint analysis of massive gravity valid for its entire parameter space, demonstrating that the model generically propagates five degrees of freedom; this is also verified by a new and streamlined Hamiltonian…

High Energy Physics - Theory · Physics 2014-12-03 S. Deser , M. Sandora , A. Waldron , G. Zahariade

Model order reduction is a technique that is used to construct low-order approximations of large-scale dynamical systems. In this paper, we investigate a balancing based model order reduction method for dynamical systems with a linear…

Optimization and Control · Mathematics 2019-09-11 Peter Benner , Pawan Goyal , Igor Pontes Duff