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We present an explicit computation of matrix elements of the hamiltonian constraint operator in non-perturbative quantum gravity. In particular, we consider the euclidean term of Thiemann's version of the constraint and compute its action…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Roumen Borissov , Roberto De Pietri , Carlo Rovelli

In canonical quantum gravity, when space is a compact manifold with boundary there is a Hamiltonian given by an integral over the boundary. Here we compute the action of this `boundary Hamiltonian' on observables corresponding to open…

General Relativity and Quantum Cosmology · Physics 2009-10-28 John Baez , Javier P. Muniain , Dardo Piriz

In a quantum theory of gravity the gravitational Wilson loop, defined as a suitable quantum average of a parallel transport operator around a large near-planar loop, provides important information about the large-scale curvature properties…

High Energy Physics - Theory · Physics 2008-11-26 Herbert W. Hamber , Ruth M. Williams

We compute explicitly the equations of motion of the Hamiltonian formulation of quadratic gravity. This is the theory with the most general Lagrangian with terms of quadratic order in the curvature tensor. We employ the symbolic…

General Relativity and Quantum Cosmology · Physics 2026-03-13 Jorge Bellorin

A covariant spin-foam formulation of quantum gravity has been recently developed, characterized by a kinematics which appears to match well the one of canonical loop quantum gravity. In particular, the geometrical observable giving the area…

General Relativity and Quantum Cosmology · Physics 2014-11-20 You Ding , Carlo Rovelli

We derive an explicit Hamiltonian for copying the basis up and down states of a quantum two-state system - a qubit - onto n "copy" qubits initially all prepared in the down state. In terms of spin components, for spin-1/2 particle spin…

Quantum Physics · Physics 2014-11-18 Dima Mozyrsky , Vladimir Privman , Mark Hillery

The Hamiltonian constraint remains an elusive object in loop quantum gravity because its action on spinnetworks leads to changes in their corresponding graphs. As a result, calculations in loop quantum gravity are often considered…

General Relativity and Quantum Cosmology · Physics 2025-07-28 Thiago L. M. Guedes , Guillermo A. Mena Marugán , Markus Müller , Francesca Vidotto

..."but we do not have quantum gravity." This phrase is often used when analysis of a physical problem enters the regime in which quantum gravity effects should be taken into account. In fact, there are several models of the gravitational…

General Relativity and Quantum Cosmology · Physics 2010-12-23 Marcin Domagala , Kristina Giesel , Wojciech Kaminski , Jerzy Lewandowski

An important aspect in understanding the dynamics in the context of deparametrized models of LQG is to obtain a sufficient control on the quantum evolution generated by a given Hamiltonian operator. More specifically, we need to be able to…

General Relativity and Quantum Cosmology · Physics 2017-08-02 Mehdi Assanioussi , Jerzy Lewandowski , Ilkka Mäkinen

The discrete picture of geometry arising from the loop representation of quantum gravity can be extended by a quantum deformation. The operators for area and volume defined in the q-deformation of the theory are partly diagonalized. The…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Roumen Borissov , Seth Major , Lee Smolin

In this work we define a new type of flux operators on the Hilbert space of loop quantum gravity. We use them to solve an equation of the form $F(A)=c\,\Sigma$ in loop quantum gravity. This equation, which relates the curvature of a…

General Relativity and Quantum Cosmology · Physics 2020-07-15 Hanno Sahlmann , Thomas Zilker

We study the scalar modes of linear perturbations in loop quantum cosmology. This is done on a lattice where each cell is taken to be homogeneous and isotropic and can be quantized via standard homogeneous loop quantum cosmology techniques.…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Edward Wilson-Ewing

Quantum-reduced loop gravity is a model of loop quantum gravity, which - from the technical point of view - is characterized by the remarkably simple form of its basic operators. In this article we examine the operators of the…

General Relativity and Quantum Cosmology · Physics 2021-01-01 Ilkka Mäkinen

We study the classical and quantum oscillator in the context of a non-additive (deformed) displacement operator, associated with a position-dependent effective mass, by means of the supersymmetric formalism. From the supersymmetric partner…

Quantum Physics · Physics 2021-09-15 Bruno G. da Costa , Genilson A. C. da Silva , Ignacio S. Gomez

We consider the coupling between three dimensional gravity with zero cosmological constant and massive spinning point particles. First, we study the classical canonical analysis of the coupled system. Then, we go to the Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Karim Noui , Alejandro Perez

This work introduces a new space $\T'_*$ of `vertex-smooth' states for use in the loop approach to quantum gravity. Such states provide a natural domain for Euclidean Hamiltonian constraint operators of the type introduced by Thiemann (and…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Jerzy Lewandowski , Donald Marolf

We show that under certain technical assumptions, including the existence of a constant mean curvature (CMC) slice and strict positivity of the scalar field, general relativity conformally coupled to a scalar field can be quantised on a…

General Relativity and Quantum Cosmology · Physics 2013-04-25 Norbert Bodendorfer , Alexander Stottmeister , Andreas Thurn

In loop quantum gravity (LQG), states of the gravitational field are represented by labeled graphs called spin networks. Their dynamics can be described by a Hamiltonian constraint, { which acts on the spin network states modifying both…

General Relativity and Quantum Cosmology · Physics 2025-11-27 Thiago L. M. Guedes , Guillermo A. Mena Marugán , Francesca Vidotto , Markus Müller

In this article we further investigate the construction of graph coherent states, first introduced in [1], in the context of loop quantum gravity. We specifically investigate the possibility of defining a family of graph coherent states…

General Relativity and Quantum Cosmology · Physics 2020-07-01 Mehdi Assanioussi

We relate three-dimensional loop quantum gravity to the combinatorial quantisation formalism based on the Chern-Simons formulation for three-dimensional Lorentzian and Euclidean gravity with vanishing cosmological constant. We compare the…

General Relativity and Quantum Cosmology · Physics 2012-02-07 C. Meusburger , K. Noui