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We propose a new formalism of quantum subsystems which allows to unify the existing and new methods of reduced description of quantum systems. The main mathematical ingredients are completely positive maps and correlation functions. In this…

Quantum Physics · Physics 2015-05-13 R. Alicki , M. Fannes , M. Pogorzelska

In these lectures I talk about simplifications and universalities found in scattering amplitudes for gauge and gravity theories. In contrast to Ward identities, which are understood to arise from familiar symmetries of the classical action,…

High Energy Physics - Theory · Physics 2015-11-10 John Joseph M. Carrasco

The evaluation of a relativistic spin network for the classical case of the Lie group SU(2) is given by an integral formula over copies of SU(2). For the graph determined by a 4-simplex this gives the evaluation as an integral over a space…

Quantum Algebra · Mathematics 2009-09-25 John W. Barrett

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 compute the complete spectrum of the area operator in the loop representation of quantum gravity, using recoupling theory. This result extends previous derivations, which did not include the ``degenerate'' sector, and agrees with the…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Simonetta Frittelli , Luis Lehner , Carlo Rovelli

We discuss how to use the recent progress in understanding of the $x$-$y$ duality and symplectic duality in the theory of topological recursion and its generalizations in order to efficiently compute the quantum spectral curve operators for…

Mathematical Physics · Physics 2025-04-22 Alexander Hock , Sergey Shadrin

We introduce a new operator representing the three-dimensional scalar curvature in loop quantum gravity. The operator is constructed by writing the Ricci scalar classically as a function of the Ashtekar variables and regularizing the…

General Relativity and Quantum Cosmology · Physics 2023-04-04 Ilkka Mäkinen

We use the recently introduced U(N) framework for loop quantum gravity to study the dynamics of spin network states on the simplest class of graphs: two vertices linked with an arbitrary number N of edges. Such graphs represent two regions,…

General Relativity and Quantum Cosmology · Physics 2011-03-28 Enrique F. Borja , Jacobo Diaz-Polo , Iñaki Garay , Etera R. Livine

After an overview of the physical motivations for studying quantum gravity, we reprint THE FORMAL STRUCTURE OF QUANTUM GRAVITY, i.e. the 1978 Cargese Lectures by Professor B.S. DeWitt, with kind permission of Springer. The reader is…

High Energy Physics - Theory · Physics 2008-11-26 Bryce S. DeWitt , Giampiero Esposito

In this article we introduce a new operator representing the three-dimensional scalar curvature in loop quantum gravity. Our construction does not apply to the entire kinematical Hilbert space of loop quantum gravity; instead, the operator…

General Relativity and Quantum Cosmology · Physics 2023-06-02 Jerzy Lewandowski , Ilkka Mäkinen

We discuss the extension of loop quantum gravity to topspin networks, a proposal which allows topological information to be encoded in spin networks. We will show that this requires minimal changes to the phase space, C*-algebra and Hilbert…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Christopher L. Duston

Group field theories represent a 2nd quantized reformulation of the loop quantum gravity state space and a completion of the spin foam formalism. States of the canonical theory, in the traditional continuum setting, have support on graphs…

General Relativity and Quantum Cosmology · Physics 2015-02-17 Daniele Oriti , James P. Ryan , Johannes Thürigen

The building blocks of a quantum theory of general relativity are expected to be discrete structures. Loop quantum gravity is formulated using a basis of spin networks (wave functions over oriented graphs with coloured edges), thus…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Jacobo Diaz-Polo , Iñaki Garay

Quantum Reduced Loop Gravity is a promising framework for linking Loop Quantum Gravity and the effective semiclassical dynamics of Loop Quantum Cosmology. We review its basic achievements and its main perspectives, outlining how it provides…

General Relativity and Quantum Cosmology · Physics 2016-08-03 Emanuele Alesci , Francesco Cianfrani

This thesis is dedicated to the study of open spin networks. We formulate quasi-local descriptions of loop quantum gravity. We investigate the coarse-graining procedure via tracing over bulk degrees of freedom, which encodes all that we can…

General Relativity and Quantum Cosmology · Physics 2023-06-08 Qian Chen

Loop quantum gravity has provided us with a canonical framework especially devised for background independent and diffeomorphism invariant gauge field theories. In this quantization the fundamental excitations are called spin network…

General Relativity and Quantum Cosmology · Physics 2010-09-28 Valentin Bonzom

We analyze Regge quantum gravity coupled to SU(2) gauge theory on $4^3\times 2$, $6^{3}\times 4$ and $8^{3}\times 4$ simplicial lattices. It turns out that the window of the well-defined phase of the gravity sector where geometrical…

High Energy Physics - Lattice · Physics 2011-09-09 B. A. Berg , W. Beirl , B. Krishnan , H. Markum , J. Riedler

In this thesis, we study the structure of Group Field Theories (GFTs) from the point of view of renormalization theory. Such quantum field theories are found in approaches to quantum gravity related to Loop Quantum Gravity (LQG) on the one…

High Energy Physics - Theory · Physics 2014-07-22 Sylvain Carrozza

We present an introduction to the canonical quantization of gravity performed in loop quantum gravity, based on lectures held at the 3rd quantum geometry and quantum gravity school in Zakopane in 2011. A special feature of this introduction…

General Relativity and Quantum Cosmology · Physics 2022-12-07 Kristina Giesel , Hanno Sahlmann

Important characteristics of the loop approach to quantum gravity are a specific choice of the algebra A of observables and of a representation of A on a measure space over the space of generalized connections. This representation is…

General Relativity and Quantum Cosmology · Physics 2011-01-27 Hanno Sahlmann