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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

We investigate the phase diagram of quantum gravity with a vertex expansion about constantly-curved backgrounds. The graviton two- and three-point function are evaluated with a spectral sum on a sphere. We obtain, for the first time,…

High Energy Physics - Theory · Physics 2019-11-28 Nicolai Christiansen , Kevin Falls , Jan M. Pawlowski , Manuel Reichert

Background independence is often emphasized as an important property of a quantum theory of gravity that takes seriously the geometrical nature of general relativity. In a background-independent formulation, quantum gravity should determine…

General Relativity and Quantum Cosmology · Physics 2021-08-27 Martin Bojowald

We propose a new method to define theories of random geometries, using an explicit and simple map between metrics and large hermitian matrices. We outline some of the many possible applications of the formalism. For example, a…

High Energy Physics - Theory · Physics 2011-12-09 Frank Ferrari , Semyon Klevtsov , Steve Zelditch

Borrowing ideas from the relation between simply laced Lie algebras and Dynkin diagrams, a weighted graph theory representation of quantum information is addressed. In this way, the density matrix of a quantum state can be interpreted as a…

High Energy Physics - Theory · Physics 2016-09-13 Abdelilah Belhaj , Adil Belhaj , Larbi Machkouri , Moulay Brahim Sedra , Soumia Ziti

In loop quantum gravity, the area element of embedded spatial surfaces is given by a well-defined operator. We further characterize the quantized geometry of such surfaces by proposing definitions for operators quantizing scalar curvature…

General Relativity and Quantum Cosmology · Physics 2018-09-26 David Grüber , Hanno Sahlmann , Thomas Zilker

The idea that the Universe is a program in a giant quantum computer is both fascinating and suffers from various problems. Nonetheless, it can provide a unified picture of physics and this can be very useful for the problem of Quantum…

General Relativity and Quantum Cosmology · Physics 2012-08-03 Fotini Markopoulou

Quantum Graph Neural Networks (QGNNs) represent a novel fusion of quantum computing and Graph Neural Networks (GNNs), aimed at overcoming the computational and scalability challenges inherent in classical GNNs that are powerful tools for…

We consider a model of Quantum Gravity phenomenology, based on the idea that space-time may have some unknown granular structure that respects the Lorentz symmetry. The proposal involves non-trivial couplings of curvature to matter fields…

General Relativity and Quantum Cosmology · Physics 2008-01-21 Y. Bonder

There ought to exist a reformulation of quantum theory which does not depend on classical time. To achieve such a reformulation, we introduce the concept of an atom of space-time-matter (STM). An STM atom is a classical non-commutative…

General Relativity and Quantum Cosmology · Physics 2019-07-17 Shounak De , Tejinder P. Singh , Abhinav Varma

We present a mapping of dynamical graphs and, in particular, the graphs used in the Quantum Graphity models for emergent geometry, into an Ising hamiltonian on the line graph of a complete graph with a fixed number of vertices. We use this…

General Relativity and Quantum Cosmology · Physics 2011-08-08 Francesco Caravelli , Fotini Markopoulou

Just as for non-abelian gauge theories at strong coupling, discrete lattice methods are a natural tool in the study of non-perturbative quantum gravity. They have to reflect the fact that the geometric degrees of freedom are dynamical, and…

High Energy Physics - Theory · Physics 2009-10-31 R. Loll

We present a line by line derivation of canonical quantum mechanics stemming from the compatibility of the statistical geometry of distinguishable observations with the canonical Poisson structure of Hamiltonian dynamics. This viewpoint can…

High Energy Physics - Theory · Physics 2017-08-23 Djordje Minic , Chia-Hsiung Tze

After a brief introduction, basic ideas of the quantum Riemannian geometry underlying loop quantum gravity are summarized. To illustrate physical ramifications of quantum geometry, the framework is then applied to homogeneous isotropic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Abhay Ashtekar

A finite discrete graph is turned into a quantum (metric) graph once a finite length is assigned to each edge and the one-dimensional Laplacian is taken to be the operator. We study the dependence of the spectral gap (the first positive…

Mathematical Physics · Physics 2018-03-28 Ram Band , Guillaume Lévy

Perturbative algebraic quantum field theory (pAQFT) is a mathematically rigorous framework that allows to construct models of quantum field theories on a general class of Lorentzian manifolds. Recently this idea has been applied also to…

Mathematical Physics · Physics 2016-04-27 Kasia Rejzner

The recently proposed Holography-inspired approach to quantum gravity is reviewed and expanded. The approach is based on the foliation of the background spacetime and reduction of the offshell states to the physical states. Careful…

High Energy Physics - Theory · Physics 2019-07-30 I. Y. Park

It is argued that quantum gravity has an interpretation as a topological field theory provided a certain constraint from the path intergral measure is respected. The constraint forces us to couple gauge and matter fields to gravity for…

High Energy Physics - Theory · Physics 2009-10-30 Andrew Toon

The local geometry of the parameter space of a quantum system is described by the quantum metric tensor and the Berry curvature, which are two fundamental objects that play a crucial role in understanding geometrical aspects of condensed…

Quantum matrix geometry is the underlying geometry of M(atrix) theory. Expanding upon the idea of level projection, we propose a quantum-oriented non-commutative scheme for generating the matrix geometry of the coset space $G/H$. We employ…

High Energy Physics - Theory · Physics 2023-12-29 Kazuki Hasebe