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It is known that the action of Euclidean Einstein gravity is not bounded from below and that the metric of flat space does not correspond to a minimum of the action. Nevertheless, perturbation theory about flat space works well. The deep…

General Relativity and Quantum Cosmology · Physics 2009-10-31 G. Modanese

In a published paper [Sengupta, 2016], we have proposed that the brain (and other self-organized biological and artificial systems) can be characterized via the mathematical apparatus of a gauge theory. The picture that emerges from this…

Neurons and Cognition · Quantitative Biology 2017-11-15 Biswa Sengupta , Karl Friston

We consider quantum Einstein gravity in three dimensional de Sitter space. The Euclidean path integral is formulated as a sum over geometries, including both perturbative loop corrections and non-perturbative instanton corrections coming…

High Energy Physics - Theory · Physics 2011-09-22 Alejandra Castro , Nima Lashkari , Alexander Maloney

We re-consider the idea that quantum fluctuations might reflect the existence of an 'objective randomness', i.e. a basic property of the vacuum state which is independent of any experimental accuracy of the observations or limited knowledge…

General Physics · Physics 2015-05-28 M. Consoli , A. Pluchino , A. Rapisarda

Quantum estimation theory provides optimal observations for various estimation problems for unknown parameters in the state of the system under investigation. However, the theory has been developed under the assumption that every observable…

Quantum Physics · Physics 2009-11-10 M. Hotta , M. Ozawa

Multimode Gaussian quantum light, including multimode squeezed and/or multipartite quadrature entangled light, is a very general and powerful quantum resource with promising applications to quantum information processing and metrology…

Quantum Physics · Physics 2010-08-05 Olivier Pinel , Julien Fade , Nicolas Treps , Claude Fabre

We investigate the uncertainty relation for estimating the position of one electron in a uniform magnetic field in the framework of the quantum estimation theory. Two kinds of momenta, canonical one and mechanical one, are used to generate…

Quantum Physics · Physics 2020-08-26 Shin Funada , Jun Suzuki

The usual derivation of Einstein's field equations from the Einstein--Hilbert action is performed by silently assuming the metric tensor's symmetric character. If this symmetry is not assumed, the result is a new theory, such as Einstein's…

General Relativity and Quantum Cosmology · Physics 2025-08-05 Viktor T. Toth

The class of Cressie-Read empirical likelihoods are constructed with weights derived at a minimum distance from the empirical distribution in the Cressie-Read family of divergences indexed by $\gamma$ under the constraint of an unbiased set…

Statistics Theory · Mathematics 2017-11-03 Laura Turbatu

Viewing gravitational energy-momentum as equal by observation, but different in essence from inertial energy-momentum naturally leads to the gauge theory of volume-preserving diffeormorphisms of an inner Minkowski space which can describe…

Mathematical Physics · Physics 2012-03-13 C. Wiesendanger

We study a perturbation theory for embedding gravity equations in a background for which corrections to the embedding function are linear with respect to corrections to the flat metric. The arbitrariness remaining after solving the…

General Relativity and Quantum Cosmology · Physics 2022-12-02 S. S. Kuptsov , M. V. Ioffe , S. N. Manida , S. A. Paston

We analyze the thermal fluctuations of a free, conformally invariant, Maxwell quantum field (photon) interacting with a cosmological background spacetime, in the framework of quantum field theory in curved spacetimes and semiclassical and…

General Relativity and Quantum Cosmology · Physics 2025-07-01 Markus B. Fröb , Dražen Glavan , Paolo Meda

We derive the runnings of the $R$ and $R^2$ operators that stem from integrating out quantum torsion fluctuations on a maximally symmetric Euclidean background, while treating the metric as a classical field. Our analysis is performed in a…

General Relativity and Quantum Cosmology · Physics 2025-04-01 Riccardo Martini , Gregorio Paci , Dario Sauro

We investigate the problem of estimating simultaneously multiple parameters encoded in the shape of the modes on which the light is expanded. For this, we generalize the mode-encoded parameter estimation theory as introduced in Ref.[1] to a…

Quantum Physics · Physics 2025-05-23 Alexander Boeschoten , Giacomo Sorelli , Manuel Gessner , Claude Fabre , Nicolas Treps

Planck-scale quantum spacetime undergoes probabilistic local curvature fluctuations whose distributions cannot explicitly depend on position otherwise vacuum's small-scale quantum structure would fail to be statistically homogeneous. Since…

High Energy Physics - Theory · Physics 2012-03-28 Christopher D. Burton

In the semi-classical regime, quantum fluctuations embedded in a Riemannian spacetime can be effectively recast as classical back reactions and manifest themselves in the form of non-minimal couplings between matter and curvature. In this…

General Relativity and Quantum Cosmology · Physics 2022-02-07 Che-Yu Chen , Yu-Hsien Kung

Environmental fluctuations degrade the performance of solid-state qubits but can in principle be mitigated by real-time Hamiltonian estimation down to time scales set by the estimation efficiency. We implement a physics-informed and an…

The microcanonical statistical mechanics of a set of self-gravitating particles is analyzed in mean-field approach. In order to deal with an upper bounded entropy functional, a softened gravitational potential is used. The softening is…

Statistical Mechanics · Physics 2008-11-26 Eduardo Follana , Victor Laliena

Many results in the quantum metrology literature use the Cram\'er-Rao bound and the Fisher information to compare different quantum estimation strategies. However, there are several assumptions that go into the construction of these tools,…

Quantum Physics · Physics 2018-01-31 Jesús Rubio , Paul Knott , Jacob Dunningham

We describe a method to computationally estimate the probability density function of a univariate random variable by applying the maximum entropy principle with some local conditions given by Gaussian functions. The estimation errors and…

Statistics Theory · Mathematics 2012-06-21 Mihail-Ioan Pop