English
Related papers

Related papers: Analysing (cosmological) singularity avoidance in …

200 papers

The quantization of the reduced phase-space of the Einstein-Hilbert action for gravity in $2+1D$ has been shown to bring about the emergence, at the quantum level, of a topological quantum field theory endowed with an $SU_q(2)$ quantum…

General Relativity and Quantum Cosmology · Physics 2023-03-08 Niels Gresnigt , Antonino Marciano , Emanuele Zappala

The leading long-distance 1-loop quantum corrections to the Coulomb potential are derived for scalar QED and their gauge-independence is explicitly checked. The potential is obtained from the direct calculation of the 2-particle scattering…

High Energy Physics - Theory · Physics 2009-10-31 J. A. Helayel-Neto , A. Penna-Firme , I. L. Shapiro

We comment on structural properties of the algebras $\mathfrak{A}_{LQG/LQC}$ underlying loop quantum gravity and loop quantum cosmology, especially the representation theory, relating the appearance of the (dynamically induced)…

General Relativity and Quantum Cosmology · Physics 2015-04-10 Alexander Stottmeister , Thomas Thiemann

We reconsider the Rovelli-Smolin model of gravity coupled to the Klein-Gordon time field with an eye towards capturing the degrees of freedom of the scalar field lost in the framework in which time is deparametrized by the scalar field.…

General Relativity and Quantum Cosmology · Physics 2016-02-03 Jerzy Lewandowski , Hanno Sahlmann

The Volume Operator plays a crucial role in the definition of the quantum dynamics of Loop Quantum Gravity (LQG). Efficient calculations for dynamical problems of LQG can therefore be performed only if one has sufficient control over the…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Johannes Brunnemann , Thomas Thiemann

Quantum reduced loop gravity is designed to consistently study symmetry reduced systems within the loop quantum gravity framework. In particular, it bridges the gap between the effective cosmological models of loop quantum cosmology and the…

General Relativity and Quantum Cosmology · Physics 2018-12-05 Emanuele Alesci , Aurélien Barrau , Gioele Botta , Killian Martineau , Gabriele Stagno

Based on a recent purely geometric construction of observables for the spatial diffeomorphism constraint, we propose two distinct quantum reductions to spherical symmetry within full 3+1-dimensional loop quantum gravity. The construction of…

General Relativity and Quantum Cosmology · Physics 2015-05-28 Norbert Bodendorfer , Jerzy Lewandowski , Jedrzej Świeżewski

The inverse scale factor, which in classical cosmological models diverges at the singularity, is quantized in isotropic models of loop quantum cosmology by using techniques which have been developed in quantum geometry for a quantization of…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Martin Bojowald

In this work we investigate the canonical quantization of 2+1 gravity with cosmological constant $\Lambda>0$ in the canonical framework of loop quantum gravity. The unconstrained phase space of gravity in 2+1 dimensions is coordinatized by…

General Relativity and Quantum Cosmology · Physics 2012-08-15 Karim Noui , Alejandro Perez , Daniele Pranzetti

Given the Loop-Quantum-Gravity (LQG) non-graph-changing Hamiltonian $\widehat{H[N]}$, the coherent state expectation value $\langle\widehat{H[N]}\rangle$ admits an semiclassical expansion in $\ell^2_{\rm p}$. In this paper, we compute…

General Relativity and Quantum Cosmology · Physics 2022-05-17 Cong Zhang , Shicong Song , Muxin Han

We present a quantum algorithm for solving the finite-horizon discrete-time Linear Quadratic Gaussian (LQG) control problem, which integrates optimal control and state estimation in the presence of stochastic disturbances and noise.…

Quantum Physics · Physics 2025-07-15 Nahid Binandeh Dehaghani , Rafal Wisniewski , A. Pedro Aguiar

We study numerically the first order radiative corrections to the self-energy, in covariant loop quantum gravity. We employ the recently developed 'sl2cfoam-next' spinfoam amplitudes library, and some original numerical methods. We analyze…

General Relativity and Quantum Cosmology · Physics 2022-09-29 Pietropaolo Frisoni , Francesco Gozzini , Francesca Vidotto

Following the same steps made for a scalar field in a parallel publication, we propose a class of perturbative theories of quantum gravity based on fractional operators, where the kinetic operator of the graviton is either made of…

General Relativity and Quantum Cosmology · Physics 2021-08-16 Gianluca Calcagni

The study of toy models in loop quantum gravity (LQG), defined as truncations of the full theory, is relevant to both the development of the LQG phenomenology, in cosmology and astrophysics, and the progress towards the resolution of the…

General Relativity and Quantum Cosmology · Physics 2022-07-13 Eneko Aranguren , Iñaki Garay , Etera R. Livine

The U(N) framework and the spinor representation for loop quantum gravity are two new points of view that can help us deal with the most fundamental problems of the theory. Here, we review the detailed construction of the U(N) framework…

General Relativity and Quantum Cosmology · Physics 2011-10-21 Enrique F. Borja , Jacobo Diaz-Polo , Iñaki Garay

This series of lectures gives a simple and self-contained introduction to the non-perturbative and background independent loop approach of canonical quantum gravity. The Hilbert space of kinematical quantum states is constructed and a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Marcus Gaul , Carlo Rovelli

We construct in this article a new realization of quantum geometry, which is obtained by quantizing the recently-introduced flux formulation of loop quantum gravity. In this framework, the vacuum is peaked on flat connections, and states…

General Relativity and Quantum Cosmology · Physics 2021-06-18 Benjamin Bahr , Bianca Dittrich , Marc Geiller

The non-factorizing nature of the Hilbert space in Loop Quantum Gravity (LQG) due to gauge invariance requires a generalized definition of entanglement entropy. This work employs the framework of von Neumann algebras to investigate the…

General Relativity and Quantum Cosmology · Physics 2025-11-04 Muxin Han

We explore the extension of quantum cosmology outside the homogeneous approximation, using the formalism of loop quantum gravity. We introduce a model where some of the inhomogeneous degrees of freedom are present, providing a tool for…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Carlo Rovelli , Francesca Vidotto

This paper deals with several technical issues of non-perturbative four-dimensional Lorentzian canonical quantum gravity in the continuum that arose in connection with the recently constructed Wheeler-DeWitt quantum constraint operator. 1)…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Thomas Thiemann