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The volume operator plays a pivotal role for the quantum dynamics of Loop Quantum Gravity (LQG), both in the full theory and in truncated models adapted to cosmological situations coined Loop Quantum Cosmology (LQC). It is therefore crucial…

General Relativity and Quantum Cosmology · Physics 2008-12-09 C. Flori , T. Thiemann

We study the properties of $\hat{Q}[\omega]$ operator on the kinematical Hilbert space ${\cal H}$ for canonical quantum gravity. Its complete spectrum with respect to the spin network basis is obtained. It turns out that $\hat{Q}[\omega]$…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Yongge Ma , Yi Ling

Representations of quantum computations are almost always based on a tensor product $\otimes$-structure. This coincides with what we are able to execute in our experiments, as well as what we observe in Nature, but it makes certain familiar…

Quantum Physics · Physics 2021-11-05 Luca Mondada

Considering as usual that the underlying geometry of our universe is well described by the spatially flat Friedmann-Lemaitre-Robertson-Walker line element, we review how the background of holonomy corrected Loop Quantum Cosmology (LQC)…

General Relativity and Quantum Cosmology · Physics 2019-05-01 Jaume de Haro , Llibert Aresté Saló , Supriya Pan

The main goal of this work is to explore the symmetries and develop the dynamics associated to a 3D Abelian BF model coupled to scalar fields submitted to a sigma model like constraint, at the classical and quantum levels. We apply to the…

General Relativity and Quantum Cosmology · Physics 2014-10-07 Diego C. M. Mendonça , Olivier Piguet

Results that illuminate the physical interpretation of states of nonperturbative quantum gravity are obtained using the recently introduced loop variables. It is shown that: i) While local operators such as the metric at a point may not be…

High Energy Physics - Theory · Physics 2011-04-20 Abhay Ashtekar , Carlo Rovelli , Lee Smolin

Relativistic quantum gravity with the action including terms quadratic in the curvture tensor is analyzed. We derive new expressions for the corresponding Lagrangian and the graviton propagator within dimensional regularization. We argue…

General Physics · Physics 2018-05-22 S. A. Larin

A quantum theory in a finite-dimensional Hilbert space can be geometrically formulated as a proper Hamiltonian theory as explained in [2, 3, 7, 8]. From this point of view a quantum system can be described in a classical-like framework…

Mathematical Physics · Physics 2017-07-26 Davide Pastorello

We start with the Hamiltonian formulation of the first order action of pure gravity with a full $\mathfrak{sl}(2,\mathbb C)$ internal gauge symmetry. We make a partial gauge-fixing which reduces $\mathfrak{sl}(2,\mathbb C)$ to its…

General Relativity and Quantum Cosmology · Physics 2017-06-28 Hongguang Liu , Karim Noui

In order to study 3d loop quantum gravity coupled to matter, we consider a simplified model of abelian quantum gravity, the so-called U(1)^3 model. Abelian gravity coupled to a scalar field shares a lot of commonalities with parameterized…

General Relativity and Quantum Cosmology · Physics 2019-05-01 Christoph Charles

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

In the paper is presented an invariant quantization procedure of classical mechanics on the phase space over flat configuration space. Then, the passage to an operator representation of quantum mechanics in a Hilbert space over…

Mathematical Physics · Physics 2015-06-16 Maciej Blaszak , Ziemowit Domanski

In Loop Quantum Gravity, the quantum action of the volume operator is crucial in understanding quantum dynamics. In this work, we implement a generalized numerical algorithm that can compute the quantum action of the volume operator on a…

General Relativity and Quantum Cosmology · Physics 2026-04-01 Haida Li , Hongguang Liu

We present a new perspective on early cosmology based on Loop Quantum Gravity. We use projected spinnetworks, coherent states and spinfoam techniques, to implement a quantum reduction of the full Kinematical Hilbert space of LQG, suitable…

General Relativity and Quantum Cosmology · Physics 2013-03-05 Emanuele Alesci

The theory of canonical linearized gravity is quantized using the Projection Operator formalism, in which no gauge or coordinate choices are made. The ADM Hamiltonian is used and the canonical variables and constraints are expanded around a…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Wayne R. Bomstad , John R. Klauder

In loop quantum gravity approach to Planck scale physics, quantum geometry is represented by superposition of the so-called spin network states. In the recent literature, a class of spin networks promising from the perspective of quantum…

General Relativity and Quantum Cosmology · Physics 2021-02-17 Grzegorz Czelusta , Jakub Mielczarek

This article presents a squeezing transformation for quantum systems associated to finite vector spaces. The physical idea of squeezing here is taken from the action of the usual squeezing operator over wave functions defined on a real…

Quantum Physics · Physics 2008-02-29 M. Ruzzi

This paper establishes a link between Noncommutative Geometry and canonical quantum gravity. A semi-finite spectral triple over a space of connections is presented. The triple involves an algebra of holonomy loops and a Dirac type operator…

High Energy Physics - Theory · Physics 2009-11-13 Johannes Aastrup , Jesper M. Grimstrup , Ryszard Nest

This article introduces operator on operator regression in quantum probability. Here in the regression model, the response and the independent variables are certain operator valued observables, and they are linearly associated with unknown…

Methodology · Statistics 2024-08-02 Suprio Bhar , Subhra Sankar Dhar , Soumalya Joardar

We present the weighted weak group inverse, which is a new generalized inverse of operators between two Hilbert spaces, introduced to extend weak group inverse for square matrices. Some characterizations and representations of the weighted…

Functional Analysis · Mathematics 2019-03-05 Dijana Mosic , Daochang Zhang