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This paper considers the use of singular perturbation approximations for a class of linear quantum systems arising in the area of linear quantum optics. The paper presents results on the physical realizability properties of the approximate…

Systems and Control · Computer Science 2011-07-29 Ian R. Petersen

The probability of there being sufficient inflation to solve the fine-tuning associated with the horizon and flatness problems has recently been shown to be exponentially small, within the context of classical general relativity. Here this…

General Relativity and Quantum Cosmology · Physics 2007-08-27 William Nelson

We explore the quantum nature of black holes by introducing an effective framework that takes into account deviations from the classical results. The approach is based on introducing quantum corrections to the classical Schwarzschild…

General Relativity and Quantum Cosmology · Physics 2022-09-14 Emanuele Binetti , Manuel Del Piano , Stefan Hohenegger , Franco Pezzella , Francesco Sannino

Homogeneous cosmological models with non-vanishing intrinsic curvature require a special treatment when they are quantized with loop quantum cosmological methods. Guidance from the full theory which is lost in this context can be replaced…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Ghanashyam Date , Kevin Vandersloot

The notion of a macroscopic quantum state must be pinned down in order to assess how well experiments probe the large-scale limits of quantum mechanics. However, the issue of quantifying so-called quantum macroscopicity is fraught with…

Quantum Physics · Physics 2025-03-12 Benjamin Yadin , Matteo Fadel

We summarize the basics of the loop representation of quantum gravity and describe the main aspects of the formalism, including its latest developments, in a reorganized and consistent form. Recoupling theory, in its graphical…

General Relativity and Quantum Cosmology · Physics 2011-09-09 Roberto De Pietri , C. Rovelli

We consider the transformations of quantum states obtainable by a process of the following sort. Combine the given input state with a specially prepared initial state of an auxiliary system. Apply a unitary transformation to the combined…

Quantum Physics · Physics 2015-10-13 Andreas Blass , Yuri Gurevich

Black holes in equilibrium and the counting of their entropy within Loop Quantum Gravity are reviewed. In particular, we focus on the conceptual setting of the formalism, briefly summarizing the main results of the classical formalism and…

General Relativity and Quantum Cosmology · Physics 2009-01-12 Alejandro Corichi

Loop quantum cosmology predicts that quantum gravity effects resolve the big-bang singularity and replace it by a cosmic bounce. Furthermore, loop quantum cosmology can also modify the form of primordial cosmological perturbations, for…

General Relativity and Quantum Cosmology · Physics 2017-06-28 Edward Wilson-Ewing

Coupling any interacting quantum mechanical system to gravity in one dimension requires the cosmological constant to belong to the matter energy spectrum and thus to be quantized, even though the gravity sector is free of any quantum…

High Energy Physics - Theory · Physics 2007-05-23 Jan Govaerts

We show how to reliably calculate quantum gravitational corrections to cosmological models using the unique effective action formalism for quantum gravity. Our calculations are model independent and apply to any ultra-violet complete theory…

High Energy Physics - Theory · Physics 2025-01-07 Xavier Calmet , Roberto Casadio , Marco Sebastianutti

The local Hamiltonian problem consists of estimating the ground-state energy (given by the minimum eigenvalue) of a local quantum Hamiltonian. First, we show the existence of a good product-state approximation for the ground-state energy of…

Quantum Physics · Physics 2016-02-04 Fernando G. S. L. Brandão , Aram W. Harrow

Loop quantum cosmology (LQC) is used to provide concrete evidence in support of the general paradigm underlying spin foam models (SFMs). Specifically, it is shown that: i) the physical inner product in the timeless framework equals the…

General Relativity and Quantum Cosmology · Physics 2009-12-10 Abhay Ashtekar , Miguel Campiglia , Adam Henderson

Quantum computers hold promise to enable efficient simulations of the properties of molecules and materials; however, at present they only permit ab initio calculations of a few atoms, due to a limited number of qubits. In order to harness…

Materials Science · Physics 2020-07-07 He Ma , Marco Govoni , Giulia Galli

Bridging between descriptions involving few large and many small quantum numbers is the main open problem in loop quantum gravity. In other words, one would like to be able to represent the same physical system in terms of a few "coarse"'…

General Relativity and Quantum Cosmology · Physics 2017-06-26 Norbert Bodendorfer

Many problems of industrial interest are NP-complete, and quickly exhaust resources of computational devices with increasing input sizes. Quantum annealers (QA) are physical devices that aim at this class of problems by exploiting quantum…

Aspects of the full theory of loop quantum gravity can be studied in a simpler context by reducing to symmetric models like cosmological ones. This leads to several applications where loop effects play a significant role when one is…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Martin Bojowald

Loop quantum cosmology applies techniques derived for a background independent quantization of general relativity to cosmological situations and draws conclusions for the very early universe. Direct implications for the singularity problem…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Martin Bojowald

An action functional for the loop quantum cosmology difference equation is presented. It is shown that by guessing the general form of the solution and optimizing the action functional with respect to the parameters in the guessed solution…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Fatimah Shojai , Ali Shojai

Coupling any interacting quantum mechanical system to gravity in one (time) dimension requires the cosmological constant to belong to the matter energy spectrum and thus to be quantised, even though the gravity sector is free of any quantum…

High Energy Physics - Theory · Physics 2007-05-23 Jan Govaerts