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The volume operator plays a central role in both the kinematics and dynamics of canonical approaches to quantum gravity which are based on algebras of generalized Wilson loops. We introduce a method for simplifying its spectral analysis,…

General Relativity and Quantum Cosmology · Physics 2009-10-30 R. Loll

Loop quantum gravity (LQG) is a quantization program for gravity based on the principles of QFT and general covariance of general relativity. Quantum states of LQG describe gravitational excitations based on graphs embedded in a spatial…

General Relativity and Quantum Cosmology · Physics 2024-10-18 Hanno Sahlmann , Waleed Sherif

As a laboratory for loop quantum gravity, we consider the canonical quantization of the three-dimensional Chern-Simons theory on a noncompact space with the topology of a cylinder. Working within the loop quantization formalism, we define…

General Relativity and Quantum Cosmology · Physics 2010-03-03 Clisthenis P. Constantinidis , Gabriel Luchini , Olivier Piguet

Coherent states in a projected Hilbert space have many useful properties. When there are conserved quantities, a representation of the entire Hilbert space is not necessary. The same issue arises when conditional observations are made with…

Quantum Physics · Physics 2016-12-28 P. D. Drummond , M. D. Reid

We revise imposition of various constraints in spin foam models of 4-dimensional general relativity. We argue that the usual simplicity constraint must be supplemented by a constraint on holonomies and together they must be inserted…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Sergei Alexandrov

Symmetries impose structure on the Hilbert space of a quantum mechanical model. The mathematical units of this structure are the irreducible representations of symmetry groups and I consider how they function as conceptual units of…

Quantum Physics · Physics 2018-01-29 N. L. Harshman

Interwiners are the building blocks of spin-network states. The space of intertwiners is the quantization of a classical symplectic manifold introduced by Kapovich and Millson. Here we show that a theorem by Minkowski allows us to interpret…

General Relativity and Quantum Cosmology · Physics 2011-03-23 Eugenio Bianchi , Pietro Dona' , Simone Speziale

We study some fundamental issues related to the Hilbert space representation of quantum mechanics in the presence of a minimal length and maximal momentum. In this framework, the maximally localized states and quasi-position representation…

General Relativity and Quantum Cosmology · Physics 2014-12-12 Amir Etemadi , Kourosh Nozari

We present a new formulation of quantum holonomy theory, which is a candidate for a non-perturbative and background independent theory of quantum gravity coupled to matter and gauge degrees of freedom. The new formulation is based on a…

General Relativity and Quantum Cosmology · Physics 2016-12-21 Johannes Aastrup , Jesper M. Grimstrup

A finite dimensional system with a quadratic Hamiltonian constraint is Dirac quantized in holomorphic, antiholomorphic and mixed representations. A unique inner product is found by imposing Hermitian conjugacy relations on an operator…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Jorma Louko

We study the interactions of the higher-spin gauge theory arising from the IKKT matrix model on a covariant quantum FLRW quantum space-time $\mathcal{M}^{1,3}_{\mathtt{J}}$, denoted as HS-IKKT. In particular, we elaborate some of the…

High Energy Physics - Theory · Physics 2024-09-19 Harold C. Steinacker , Tung Tran

The quantum states or Hilbert spaces for the quantum field theory in de Sitter space-time are studied on ambient space formalism. In this formalism, the quantum states are only depended $(1)$ on the topological character of the de Sitter…

General Relativity and Quantum Cosmology · Physics 2016-07-27 M. V. Takook

Recent developments in gravitational path integrals indicate that the nonperturbative physical Hilbert space of a closed universe is one-dimensional within each superselection sector. This raises a basic puzzle: how can a unique…

High Energy Physics - Theory · Physics 2026-03-03 Yasunori Nomura , Tomonori Ugajin

In this study, we model a spin-network in loop quantum gravity as a regular tetrahedral lattice, applying lattice physics techniques to study its structure and vertex dynamics. Using the area eigenvalue, $A\propto 8\pi l_P^2$, we derive a…

General Relativity and Quantum Cosmology · Physics 2025-07-22 Noah M. MacKay

Quantum systems are viewed as emergent systems from the fundamental degrees of freedom. The laws and rules of quantum mechanics are understood as an effective description, valid for the emergent systems and specially useful to handle…

Mathematical Physics · Physics 2025-11-26 Ricardo Gallego Torromé

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

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

We describe a scheme for the exploration of quantum gravity phenomenology focussing on effects that could be thought as arising from a fundamental granularity of space-time. In contrast with the simplest assumptions, such granularity is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Yuri Bonder , Daniel Sudarsky

A common misconception is that Lorentz invariance is inconsistent with a discrete spacetime structure and a minimal length: under Lorentz contraction, a Planck length ruler would be seen as smaller by a boosted observer. We argue that in…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Etera R. Livine , Daniele Oriti

Loop quantum gravity methods are applied to a symmetry-reduced model with homogeneity in two dimensions, derived from a Gowdy model [5,6]. The conditions for propagation of unidirectional plane gravitational waves at exactly the speed of…

General Relativity and Quantum Cosmology · Physics 2025-04-28 F. Hinterleitner