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In hybrid classical-quantum theories, the dynamics of the classical system induce the classicality of the quantum system, meaning that such models do not necessarily require a measurement postulate to describe probabilistic measurement…

General Relativity and Quantum Cosmology · Physics 2024-02-28 Zachary Weller-Davies

In a remarkable paper, T. Koslowski introduced kinematical representations for loop quantum gravity in which there is a non-degenerate spatial background metric present. He also considered their properties, and showed that Gauss and…

General Relativity and Quantum Cosmology · Physics 2010-10-27 Hanno Sahlmann

A general nonperturvative loop quantization procedure for metric modified gravity is reviewed. As an example, this procedure is applied to scalar-tensor theories of gravity. The quantum kinematical framework of these theories is rigorously…

General Relativity and Quantum Cosmology · Physics 2013-04-09 Xiangdong Zhang , Yongge Ma

Two sets of spatially diffeomorphism invariant operators are constructed in the loop representation formulation of quantum gravity. This is done by coupling general relativity to an anti- symmetric tensor gauge field and using that field to…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Lee Smolin

We study a physically motivated representation of an algebra of operators in gravitational and non gravitational theories called the covariant representation of an algebra. This is a representation where the symmetries of the operator…

High Energy Physics - Theory · Physics 2023-08-29 Eyoab Bahiru

We introduce a quantum algorithm for computing the Ollivier Ricci curvature, a discrete analogue of the Ricci curvature defined via optimal transport on graphs and general metric spaces. This curvature has seen applications ranging from…

Quantum Physics · Physics 2025-12-11 Nhat A. Nghiem , Linh Nguyen , Tuan K. Do , Tzu-Chieh Wei , Trung V. Phan

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

We introduce a new loop expansion that provides a resolution of the identity in the Hilbert space of loop quantum gravity on a fixed graph. We work in the bosonic representation obtained by the canonical quantization of the spinorial…

General Relativity and Quantum Cosmology · Physics 2016-11-02 Eugenio Bianchi , Jonathan Guglielmon , Lucas Hackl , Nelson Yokomizo

A new canonical Hopf algebra called the quantum pseudo-K\"ahler plane is introduced. This quantum group can be viewed as a deformation quantization of the complex two-dimensional plane $\mathbb{C}^2$ with a pseudo-K\"ahler metric, or as a…

Representation Theory · Mathematics 2023-07-06 Hyun Kyu Kim

This article presents a simplified version of the author's previous work. We first construct a causal growth process (CGP). We then form path Hilbert spaces using paths of varying lengths in the CGP. A sequence of positive operators on…

Mathematical Physics · Physics 2013-05-23 Stan Gudder

We study a generalized version of the Hamiltonian constraint operator in nonperturbative loop quantum gravity. The generalization is based on admitting arbitrary irreducible SU(2) representations in the regularization of the operator, in…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Marcus Gaul , Carlo Rovelli

I propose a quantum gravity model in which geometric space emerges from random bits in a quantum phase transition driven by the combinatorial Ollivier-Ricci curvature and corresponding to the condensation of short cycles in random graphs.…

High Energy Physics - Theory · Physics 2017-10-25 Carlo A. Trugenberger

Using a new procedure based on Kummer's Confluent Hypergeometric Functions, we investigate the question of singularity avoidance in loop quantum gravity (LQG) in the context of U$(1)^3$ complexifier coherent states and compare obtained…

General Relativity and Quantum Cosmology · Physics 2021-09-16 Kristina Giesel , David Winnekens

We construct the regularised Wheeler-De Witt operator demanding that the algebra of constraints of quantum gravity is anomaly free. We find that for a subset of all wavefunctions being integrals of scalar densities this condition can be…

General Relativity and Quantum Cosmology · Physics 2016-08-15 A. Błaut , J. Kowalski-Glikman

Hilbert space representations of quantum SU(2) by multiplication operators on a local chart are constructed, where the local chart is given by tensor products of square integrable functions on a quantum disc and on the classical unit…

Quantum Algebra · Mathematics 2018-02-20 Elmar Wagner

The kinematics of loop gravity can be given a manifestly Lorentz-covariant formulation: the conventional SU(2)-spin-network Hilbert space can be mapped to a space K of SL(2,C) functions, where Lorentz covariance is manifest. K can be…

General Relativity and Quantum Cosmology · Physics 2011-05-25 Carlo Rovelli , Simone Speziale

A short review of scalar curvature invariants in gravity theories is presented. We introduce how these invariants are constructed and discuss the minimal number of invariants required for a given spacetime. We then discuss applications of…

General Relativity and Quantum Cosmology · Physics 2021-06-14 B. Shakerin , D. D. McNutt , B. Mattingly , A. Kar , W. Julius , M. Gorban , C. Watson , P. Brown , J. S. Lee , E. W. Davis , G. B. Cleaver

Building on the recently introduced notion of quantum Ricci curvature and motivated by considerations in nonperturbative quantum gravity, we advocate a new, global observable for curved metric spaces, the curvature profile. It is obtained…

General Relativity and Quantum Cosmology · Physics 2021-02-03 J. Brunekreef , R. Loll

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

The quantization of the Hamiltonian for a scalar field is performed in the framework of Quantum Reduced Loop Gravity. We outline how the regularization can be performed by using the analogous tools adopted in full Loop Quantum Gravity and…

General Relativity and Quantum Cosmology · Physics 2015-12-23 Jakub Bilski , Emanuele Alesci , Francesco Cianfrani