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We study the effective stochastic dynamics of a semiclassical probe induced by linear optomechanical interactions with a quantum oscillator. Quantum fluctuations lead to state-dependent non-equilibrium noise, which is exponentially enhanced…

Quantum Physics · Physics 2026-01-08 Pedro V. Paraguassú , Luca Abrahão , Thiago Guerreiro

Within the framework of loop quantum cosmology, there exists a semi-classical regime where spacetime may be approximated in terms of a continuous manifold, but where the standard Friedmann equations of classical Einstein gravity receive…

General Relativity and Quantum Cosmology · Physics 2009-11-10 James E. Lidsey

Developments in theoretical cosmology in the recent decades show a close connection with particle physics, quantum gravity and unified theories. Answers or hints to many fundamental questions in cosmology like the homogeneity and isotropy…

General Relativity and Quantum Cosmology · Physics 2007-05-23 B. L. Hu

Using the concept of open systems where the classical geometry is treated as the system and the quantum matter field as the environment, we derive a fluctuation-dissipation theorem for semiclassical cosmology. This theorem which exists…

General Relativity and Quantum Cosmology · Physics 2008-11-26 B. L. Hu , Sukanya Sinha

The quantum to classical transition of fluctuations in the early universe is still not completely understood. Some headway has been made incorporating the effects of decoherence and the squeezing of states, though the methods and procedures…

General Relativity and Quantum Cosmology · Physics 2021-05-24 Fulvio Melia

An elementary prediction of the quantization of the gravitational field is that the Newtonian interaction can entangle pairs of massive objects. Conversely, in models of gravity in which the field is not quantized, the gravitational…

Quantum Physics · Physics 2026-05-15 Giuseppe Fabiano , Tomohiro Fujita , Akira Matsumura , Daniel Carney

Semi-classical theories are approximations to quantum theory that treat some degrees of freedom classically and others quantum mechanically. In the usual approach, the quantum degrees of freedom are described by a wave function which…

Quantum Physics · Physics 2020-06-03 Ward Struyve

We present a semiclassical gravity in the framework of the double scale theory, a new interpretation of quantum mechanics which expands on the de Broglie-Bohm (dBB) theory. In this interpretation, any quantum system is associated with two…

General Physics · Physics 2023-02-23 Michel Gondran , Alexandre Gondran

In this talk, I present a theory of quantum gravity beyond Einstein. The theory is established based on spinnic and scaling gauge symmetries by treating the gravitational force on the same footing as the electroweak and strong forces. A…

High Energy Physics - Theory · Physics 2015-11-04 Yue-Liang Wu

The focus of this PhD thesis is on applications, new developments and extensions of the noncommutative gravity theory proposed by Julius Wess and his group. In part one we propose an extension of the usual symmetry reduction procedure to…

Mathematical Physics · Physics 2012-10-04 Alexander Schenkel

A link between canonical quantum gravity and fermionic quantum field theory is established in this paper. From a spectral triple construction which encodes the kinematics of quantum gravity semi-classical states are constructed which, in a…

High Energy Physics - Theory · Physics 2011-05-03 Johannes Aastrup , Jesper M. Grimstrup

In any quantum theory of gravity, it is of the utmost importance to recover the limit of quantum theory in an external spacetime. In quantum geometrodynamics (quantization of general relativity in the Schr\"odinger picture), this leads in…

General Relativity and Quantum Cosmology · Physics 2016-12-07 Claus Kiefer , Branislav Nikolic

We give a short update of our research program on nonequilibrium statistical field theory applied to quantum processes in the early universe and black holes, as well as the development of stochastic gravity theory as an extension of…

General Relativity and Quantum Cosmology · Physics 2009-11-10 B. L. Hu , Albert Roura , Sukanya Sinha , E. Verdaguer

Motivated by the gravity/fluid correspondence, we introduce a new method for characterizing nonlinear gravitational interactions. Namely we map the nonlinear perturbative form of the Einstein equation to the equations of motion of a…

General Relativity and Quantum Cosmology · Physics 2015-04-16 Huan Yang , Fan Zhang , Stephen R. Green , Luis Lehner

We consider spinfoam quantum gravity. We show in a simple case that the amplitude projects over a nontrivial (curved) classical geometry. This suggests that, at least for spinfoams without bubbles and for large values of the boundary spins,…

General Relativity and Quantum Cosmology · Physics 2013-01-09 Elena Magliaro , Claudio Perini

We investigate the nature of a gravitational two-state system (G2S) in the simplest setup in Newtonian gravity. In a quantum description of matter a single motionless massive particle can in principle be in a superposition state of two…

Quantum Physics · Physics 2015-08-26 Charis Anastopoulos , Bei-Lok Hu

We argue that recent developments in discretizations of classical and quantum gravity imply a new paradigm for doing research in these areas. The paradigm consists in discretizing the theory in such a way that the resulting discrete theory…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Rodolfo Gambini , Jorge Pullin

Effects of space time geometry fluctuations on fermionic fields have recently been looked for in nuclear physics experiments, and were found to be much lower than predicted, at a phenomenological level, by loop quantum gravity. We show that…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Gustavo Dotti , Reinaldo J. Gleiser

The possible cosmological effects of primordial fluctuation corrections to the evolution equation of matter obtained from the Wheeler--De Witt equation are explored. In particular, both the metric and a scalar matter field are expanded…

General Relativity and Quantum Cosmology · Physics 2008-11-26 C. Bertoni , E. Carretti , F. Finelli , A. Messina , G. Venturi

The intuitive classical space-time picture breaks down in quantum gravity, which makes a comparison and the development of semiclassical techniques quite complicated. Using ingredients of the group averaging method to solve constraints one…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Martin Bojowald , Parampreet Singh , Aureliano Skirzewski