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Recent cosmological measurements suggest the possibility of an anisotropic universe. As a result, the Bianchi Type I model, being the simplest anisotropic extension to the standard Friedmann-Lema\^itre-Robertson-Walker metric has been…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-05 Boris Hoi-Lun Ng , Ming-Chung Chu

We use the method of embedding a subsystem (i.e. its observable algebra) into a larger quantum system to extract a cosmological sector from full Loop Quantum Gravity. The application of this method provides a setting for a systematic study…

General Relativity and Quantum Cosmology · Physics 2007-11-08 Tim A. Koslowski

Usual approaches to quantisation of a 3-Toda lead to numerical calculations requiring many steps that can be time consuming to insure their reliability. In order to reduce as much as possible the numerical part of the EKB quantisation…

General Relativity and Quantum Cosmology · Physics 2023-01-11 Herve Bergeron , Ewa Czuchry

To avoid instabilities in the continuum semi-classical limit of loop quantum cosmology models, refinement of the underlying lattice is necessary. The lattice refinement leads to new dynamical difference equations which, in general, do not…

General Relativity and Quantum Cosmology · Physics 2008-12-18 William Nelson , Mairi Sakellariadou

Isotropic models in loop quantum cosmology allow explicit calculations, thanks largely to a completely known volume spectrum, which is exploited in order to write down the evolution equation in a discrete internal time. Because of genuinely…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Martin Bojowald

We present a reconstruction algorithm for cosmological models based on $f(\mathcal{Q})$ gravity. We specifically focus on obtaining exact Bianchi Type-I and Friedmann-Lema\^{\i}tre-Robertson-Walker solutions, finding solutions that might…

General Relativity and Quantum Cosmology · Physics 2022-05-12 Fabrizio Esposito , Sante Carloni , Roberto Cianci , Stefano Vignolo

A free massless scalar field is coupled to homogeneous and isotropic loop quantum cosmology. The coupled model is investigated in the vicinity of the classical singularity, where discreteness is essential and where the quantum model is…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Martin Bojowald , Franz Hinterleitner

The use of techniques from loop quantum gravity for cosmological models may solve some difficult problems in quantum cosmology. The solutions under a number of circumstances have been well studied. We will analyse the behaviour of solutions…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Daniel Green , William G. Unruh

A theoretical model of shape-anisometric particles embedded in a cubic lattice is formulated for binary mixtures combining rod-like, plate-like and spherical particles. The model aims at providing a tool for the prediction and…

Soft Condensed Matter · Physics 2011-05-31 Stavros Peroukidis , Alexandros G. Vanakaras , Demetri J. Photinos

We present a new cosmological model derived from Loop Quantum Gravity. The formulation is based on a projection of the kinematical Hilbert space of the full theory down to a subspace representing the proper arena for an inhomogeneous…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Emanuele Alesci , Francesco Cianfrani

We analyze the quantum Bianchi I model in the setting of the nonstandard loop quantum cosmology. Elementary observables are used to quantize the volume operator. The spectrum of the volume operator is bounded from below and discrete. The…

General Relativity and Quantum Cosmology · Physics 2011-04-04 Przemyslaw Malkiewicz , Wlodzimierz Piechocki , Piotr Dzierzak

We show how to use polar molecules in an optical lattice to engineer quantum spin models with arbitrary spin S >= 1/2 and with interactions featuring a direction-dependent spin anisotropy. This is achieved by encoding the effective spin…

We study the dynamics of states perturbatively expanded about a harmonic system of loop quantum cosmology, exhibiting a bounce. In particular, the evolution equations for the first and second order moments of the system are analyzed. These…

General Relativity and Quantum Cosmology · Physics 2011-01-20 Martin Bojowald , David Mulryne , William Nelson , Reza Tavakol

The cosmic, general analitic solutions of the Brans--Dicke Theory for the flat space of homogeneous and isotropic models containing perfect, barotropic, fluids are seen to belong to a wider class of solutions --which includes cosmological…

General Relativity and Quantum Cosmology · Physics 2016-08-31 P. Chauvet , J. L. Cervantes-Cota

In arXiv:2603.18175, the authors argue, based on numerical studies of particular cases, that the quantum damping of cosmological shear in a modified loop quantum cosmological model (mLQC-I) that was recently found in arXiv:2510.14021 is not…

General Relativity and Quantum Cosmology · Physics 2026-04-13 Wen-Cong Gan , Leila L. Graef , Rudnei O. Ramos , Gustavo S. Vicente , Anzhong Wang

We propose a quantum symmetry reduction of loop quantum gravity to Bianchi I spacetimes. To this end, we choose the diagonal metric gauge for the spatial diffeomorphism constraint at the classical level, leading to an…

General Relativity and Quantum Cosmology · Physics 2015-04-16 Norbert Bodendorfer

We establish an intriguing connection between quantum phase transitions and bifurcations in the reduced fidelity between two different reduced density matrices for quantum lattice many-body systems with symmetry-breaking orders. Our finding…

Strongly Correlated Electrons · Physics 2009-05-20 Jin-Hua Liu , Qian-Qian Shi , Jian-Hui Zhao , Huan-Qiang Zhou

Starting from an anisotropic flat cosmological model(Bianchi type $I$), we show that conditions leading to isotropisation fall into 3 classes, respectively 1, 2, 3. We look for necessary conditions such that a Bianchi type $I$ model reaches…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Stephane Fay , Jean-Pierre Luminet

The entanglement entropy of the ground state of a quantum lattice model with local interactions usually satisfies an area law. However, in 1D systems some violations may appear in inhomogeneous systems or in random systems. In our…

Quantum Physics · Physics 2018-05-08 Giovanni Ramírez

We construct families of symmetric, antisymmetric, and asymmetric solitary modes in one-dimensional bichromatic lattices with the second-harmonic-generating ($\chi ^{(2)}$) nonlinearity concentrated at a pair of sites placed at distance…

Pattern Formation and Solitons · Physics 2013-07-17 V. A. Brazhnyi , B. A. Malomed