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The ingoing and outgoing null expansions associated to a spatial 2-sphere are quantized in the spherically symmetric model of loop quantum gravity. It is shown that the resulting expansion operators are self-adjoint in the kinematical…

General Relativity and Quantum Cosmology · Physics 2026-04-22 Xiaotian Fei , Gaoping Long , Yongge Ma , Cong Zhang

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

In this article we examine a Hamiltonian constraint operator governing the dynamics of simple quantum states, whose graph consists of a single six-valent vertex, in quantum-reduced loop gravity. To this end, we first derive the action of…

General Relativity and Quantum Cosmology · Physics 2025-05-01 Ilkka Mäkinen

Shape dynamics is a reformulation of general relativity, locally equivalent to Einstein's theory, in which the refoliation invariance of the older theory is traded for local scale invariance. Shape dynamics is here derived in a formulation…

General Relativity and Quantum Cosmology · Physics 2017-05-26 Lee Smolin

The phenomenology for the deep spatial geometry of loop quantum gravity is discussed. In the context of a simple model of an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Seth A. Major

The problem of defining correctly geometric objects such as the curvature is a hard one in discrete geometry. In 2009, Ollivier defined a notion of curvature applicable to a wide category of measured metric spaces, in particular to graphs.…

Differential Geometry · Mathematics 2014-03-10 Benoît Loisel , Pascal Romon

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

In this thesis we consider the problem of dynamics in canonical loop quantum gravity, primarily in the context of deparametrized models, in which a scalar field is taken as a physical time variable for the dynamics of the gravitational…

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

We describe preliminary results of a detailed numerical analysis of the volume operator as formulated by Ashtekar and Lewandowski. Due to a simplified explicit expression for its matrix elements, it is possible for the first time to treat…

General Relativity and Quantum Cosmology · Physics 2009-11-11 J. Brunnemann , D. Rideout

We discuss a new approach to the problem of quantum gravity in which the quantum mechanical structures that are traditionally fixed, such as the Fubini-Study metric in the Hilbert space of states, become dynamical and so implement the idea…

General Relativity and Quantum Cosmology · Physics 2022-11-28 Per Berglund , Tristan Hübsch , David Mattingly , Djordje Minic

A generalized Clifford manifold is proposed in which there are coordinates not only for the basis vector generators, but for each element of the Clifford group, including the identity scalar. These new quantities are physically interpreted…

General Relativity and Quantum Cosmology · Physics 2007-05-23 William M. Pezzaglia

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

Within the context of loop quantum gravity there are several operators which measure geometry quantities. This work examines two of these operators, volume and angle, to study quantum geometry at a single spin network vertex - ``an atom of…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Seth A. Major , Michael D. Seifert

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

We study the renormalization of the Ricci curvature as an example of generally covariant operators in quantum gravity near two dimensions. We find that it scales with a definite scaling dimension at short distance. The Ricci curvature…

High Energy Physics - Theory · Physics 2016-09-06 Yoshihisa Kitazawa , Masao Ninomiya

A new link between tetrahedra and the group SU(2) is pointed out: by associating to each face of a tetrahedron an irreducible unitary SU(2) representation and by imposing that the faces close, the concept of quantum tetrahedron is seen to…

General Relativity and Quantum Cosmology · Physics 2009-10-30 A. Barbieri

The ZX-calculus, and the variant we consider in this paper (ZXH-calculus), are formal diagrammatic languages for qubit quantum computing. We show that it can also be used to describe SU(2) representation theory. To achieve this, we first…

Quantum Physics · Physics 2022-11-21 Richard D. P. East , Pierre Martin-Dussaud , John Van de Wetering

It is well known that the quantum double structure plays an important role in three dimensional quantum gravity coupled to matter field. In this paper, we show how this algebraic structure emerges in the context of three dimensional…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Karim Noui

In the previous article a new combinatorial and thus purely algebraical approach to quantum gravity, called Algebraic Quantum Gravity (AQG), was introduced. In the framework of AQG existing semiclassical tools can be applied to operators…

General Relativity and Quantum Cosmology · Physics 2008-11-26 K. Giesel , T. Thiemann

In this paper, we are going to discuss the gauge reduction with respect to the simplicity constraint in both classical and quantum theory of all dimensional loop quantum gravity. With the gauge reduction with respect to edge-simplicity…

General Relativity and Quantum Cosmology · Physics 2023-03-08 Gaoping Long , Xiangdong Zhang