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This paper considers the problem of robust stability for a class of uncertain nonlinear quantum systems subject to unknown perturbations in the system Hamiltonian. The nominal system is a linear quantum system defined by a linear vector of…

Quantum Physics · Physics 2016-11-17 Ian R. Petersen

In order to deal with a large cosmological constant a relaxation mechanism based on modified gravity has been proposed recently. By virtue of this mechanism the effect of the vacuum energy density of a given quantum field/string theory (no…

General Relativity and Quantum Cosmology · Physics 2012-01-31 Spyros Basilakos , Florian Bauer , Joan Sola

We study the loop quantum cosmology of a flat Friedmann-Lemaitre-Robertson-Walker space-time with a Maxwell field. We show that many of the qualitative properties derived for the case of a massless scalar field also hold for a Maxwell…

General Relativity and Quantum Cosmology · Physics 2015-01-07 Tomasz Pawlowski , Roberto Pierini , Edward Wilson-Ewing

In this paper we consider FRW cosmology in modified non-local gravity. The stability analysis shows that there is only one stable critical point for the model and the universe undergoes a quintessence dominated era.

General Relativity and Quantum Cosmology · Physics 2011-06-09 H. Farajollahi , F. Milani

One of critical components of Loop Quantum Gravity (LQG) and Cosmology (LQC) -- Thiemann regularization procedure is non-unique. Different choices of particular prescriptions lead to models which differ in both mathematical structure and…

General Relativity and Quantum Cosmology · Physics 2022-12-26 Maciej Kowalczyk , Tomasz Pawłowski

We study the evolution of linear perturbations in metric f(R) models of gravity and identify a potentially observable characteristic scale-dependent pattern in the behavior of cosmological structures. While at the background level viable…

Astrophysics · Physics 2014-11-18 Levon Pogosian , Alessandra Silvestri

A consistent implementation of quantum gravity is expected to change the familiar notions of space, time and the propagation of matter in drastic ways. This will have consequences on very small scales, but also gives rise to correction…

General Relativity and Quantum Cosmology · Physics 2009-08-26 Martin Bojowald , Golam Mortuza Hossain , Mikhail Kagan , S. Shankaranarayanan

Using Heisenberg's uncertainty principle it is shown that the gravitational stability condition for a crystalline vacuum cosmic space implies to obtain an equation formally equivalent to the relation first used by Gamow to predict the…

We study the dynamics of the scalar modes of linear perturbations around a flat, homogeneous and isotropic background in loop quantum cosmology. The equations of motion include quantum geometry effects and hold at all curvature scales so…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Edward Wilson-Ewing

Research during the last decade demonstrates that effects originating on the Planck scale are currently being tested in multiple observational contexts. In this review we discuss quantum gravity phenomenological models and their possible…

General Relativity and Quantum Cosmology · Physics 2012-12-14 Florian Girelli , Franz Hinterleitner , Seth A. Major

A general nonperturvative loop quantization procedure for metric modified gravity is reviewed. As an example, this procedure is applied to scalar-tensor theories of gravity. The quantum kinematical framework of these theories is rigorously…

General Relativity and Quantum Cosmology · Physics 2013-04-09 Xiangdong Zhang , Yongge Ma

In this paper we study dynamics of the closed FRW model with holonomy corrections coming from loop quantum cosmology. We consider models with a scalar field and cosmological constant. In case of the models with cosmological constant and…

General Relativity and Quantum Cosmology · Physics 2009-11-19 Jakub Mielczarek , Orest Hrycyna , Marek Szydlowski

We investigate the stability of continuous-time quantum walks (CTQW) across cycle, complete, star, Erd\H{o}s-R\'enyi, small-world, and scale-free topologies under energy-based intrinsic decoherence, node-based Haken-Strobl noise, and…

Quantum Physics · Physics 2026-03-20 Adithya L J , Johannes Nokkala , Jyrki Piilo , Chandrakala Meena

Quantum measurements have intrinsic properties which seem incompatible with our everyday-life macroscopic measurements. Macroscopic Quantum Measurement (MQM) is a concept that aims at bridging the gap between well understood microscopic…

Quantum Physics · Physics 2018-01-17 Marc-Olivier Renou , Nicolas Gisin , Florian Fröwis

Stability of the Einstein static universe versus the linear scalar, vector and tensor perturbations is investigated in the context of deformed Ho\v{r}ava-Lifshitz cosmology inspired by entropic force scenario. A general stability condition…

General Relativity and Quantum Cosmology · Physics 2017-02-14 Y. Heydarzade , M. Khodadi , F. Darabi

One of the most disturbing difficulties in thinking about the cosmological constant is that it is not stable under radiative corrections. The feedback mechanism proposed in [hep-th/0306108] is a dynamical way to protect a zero or small…

High Energy Physics - Theory · Physics 2014-11-18 Shinji Mukohyama

Cosmological perturbations in Loop Quantum Cosmology (LQC) are usually studied incorporating either holonomy corrections, where the Ashtekar connection is replaced by a suitable sinus function in order to have a well-defined quantum…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Jaime Haro

In this paper, a new Hamiltonian constraint operator for loop quantum cosmology is constructed by using the Chern-Simons action. The quantum dynamics of the $k=0$ cosmological model with respect to a massless scalar field as an emergent…

General Relativity and Quantum Cosmology · Physics 2019-09-23 Jinsong Yang , Cong Zhang , Yongge Ma

We explore the extension of quantum cosmology outside the homogeneous approximation, using the formalism of loop quantum gravity. We introduce a model where some of the inhomogeneous degrees of freedom are present, providing a tool for…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Carlo Rovelli , Francesca Vidotto

First, we review the $C^\ast$-algebraic foundations of loop quantization, in particular, the construction of quantum configuration spaces and the implementation of symmetries. Then, we apply these results to loop quantum gravity, focusing…

Mathematical Physics · Physics 2015-07-21 Christian Fleischhack