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The nonequilibrium dynamics of quantum fields is studied in inflationary cosmology, with particular emphasis on applications to the problem of post-inflation reheating. The Schwinger-Keldysh closed-time-path (CTP) formalism is utilized…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Stephen A. Ramsey

In her Comment arXiv:1202.4066 [hep-th] Hossenfelder proposes a generalization of the results we reported in Phys. Rev. D84 (2011) 087702 and argues that thermal fluctuations introduce incurable pathologies for the description of…

High Energy Physics - Theory · Physics 2013-07-18 Giovanni Amelino-Camelia , Laurent Freidel , Jerzy Kowalski-Glikman , Lee Smolin

In ultracold gases many experiments use atom imaging as a basic observable. The resulting image is averaged over a number of realizations and mostly only this average is used. Only recently the noise has been measured to extract physical…

Statistical Mechanics · Physics 2015-05-13 G. E. Astrakharchik , R. Combescot , L. P. Pitaevskii

We obtain a fluctuation--dissipation theorem describing thermal electromagnetic fluctuation effects in nonlinear media that we exploit in conjunction with a stochastic Langevin framework to study thermal radiation from Kerr ($\chi^{(3)}$)…

Mesoscale and Nanoscale Physics · Physics 2015-03-23 Chinmay Khandekar , Adi Pick , Steven G. Johnson , Alejandro W. Rodriguez

We study cosmological perturbations arising from thermal fluctuations in the big-bounce cosmology in the Einstein-Cartan-Sciama-Kibble theory of gravity. We show that such perturbations cannot have a scale-invariant spectrum if fermionic…

Cosmology and Nongalactic Astrophysics · Physics 2012-01-05 Nikodem J. Poplawski

We study the dynamics of scalar metric fluctuations in a non-perturbative variational formalism recently introduced, by which the dynamics of an geometrical scalar field $\theta$, describes the quantum geometrical effects on a Weylian-like…

General Relativity and Quantum Cosmology · Physics 2015-12-15 Mauricio Bellini

In this paper we study a quantum field theoretical approach, where a quantum probe is used to investigate the properties of generic non-flat FRLW space time. The fluctuations related to a massless conformal coupled scalar field defined on a…

General Relativity and Quantum Cosmology · Physics 2015-11-24 Y. Rabochaya

Thermodynamic uncertainty principles make up one of the few rare anchors in the largely uncharted waters of nonequilibrium systems, the fluctuation theorems being the more familiar. In this work we aim to trace the uncertainties of…

Statistical Mechanics · Physics 2022-08-02 Hang Dong , Daniel Reiche , Jen-Tsung Hsiang , Bei-Lok Hu

We present a microscopic theory of zero-temperature order parameter and pseudospin stiffness reduction due to quantum fluctuations in the ground state of double-layer quantum Hall ferromagnets. Collective excitations in this systems are…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Yogesh N. Joglekar , Allan H. MacDonald

We consider the back-reaction of cosmological fluctuations on the local expansion rate averaged over a space-like hypersurface of constant value of a clock field. We show that in the infrared limit, the fluctuations lead to a decrease in…

General Relativity and Quantum Cosmology · Physics 2023-02-14 Vincent Comeau , Robert Brandenberger

We study the effect of thermal blurring caused by the use of (momentum-space) rapidity as a proxy of coordinate-space rapidity in experimental measurements of conserved charge fluctuations in relativistic heavy ion collisions. In…

Nuclear Theory · Physics 2016-10-19 Yutaro Ohnishi , Masakiyo Kitazawa , Masayuki Asakawa

We study quantum fluctuations of a free massless scalar field during inflation in the presence of a point, line, or plane defect such as a black hole, cosmic string, or domain wall, using a perturbative expansion in powers of small defect…

High Energy Physics - Theory · Physics 2015-06-19 Hing-Tong Cho , Kin-Wang Ng , I-Chin Wang

Detailed measurements of the cosmic microwave background indicate the large-scale homogeneity of the universe. On very small scales, we observe however inhomogeneities such as galaxies, stars, planets and ourselves. In the context of hot…

General Relativity and Quantum Cosmology · Physics 2019-07-02 Wouter Ryssens

Deviations from the Friedmann-Robertson-Walker (FRW) cosmological model in the form of density inhomogeneities induce observational effects on the light propagating through these fluctuations. Using a rigorously parametrized metric whose…

Astrophysics · Physics 2007-05-23 Eric V. Linder

The spatial and temporal noise properties of diffuse radiation is investigated in the context of the cosmic microwave background (CMB), although generic formulae that enable application to any other forms of incoherent light of a prescribed…

Cosmology and Nongalactic Astrophysics · Physics 2009-06-02 Richard Lieu , Bizhu Jiang

The event horizon is a source of irreversibility, analogous to statistical irreversibility. This is why for systems with an event horizon there is no difference between quantum and thermal fluctuations. Quantum processes of quantum…

General Relativity and Quantum Cosmology · Physics 2025-10-16 G. E. Volovik

We revisit the quantum theory of a massive, minimally coupled scalar field, propagating on the Planck-era isotropic cosmological quantum spacetime which transitions to a classical spacetime in later times. The quantum effects modify the…

General Relativity and Quantum Cosmology · Physics 2020-03-06 Saeed Rastgoo , Yaser Tavakoli , Julio C. Fabris

We consider a model of modified gravity from the nonperturbative quantization of a metric. We obtain the modified gravitational field equations and the modified conservational equations. We apply it to the FLRW spacetime and find that due…

General Relativity and Quantum Cosmology · Physics 2016-05-20 Rong-Jia Yang

Linearized fluctuations of quantized matter fields and the spacetime geometry around de Sitter space are considered in the case that the matter fields are conformally invariant. Taking the unperturbed state of the matter to be the de Sitter…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Paul R. Anderson , Carmen Molina-Paris , Emil Mottola

Fluctuations are significant in mesoscopic systems and of particular importance in understanding quantum transport. Here, we show that fluctuations can be considered as a resource for the operations of open quantum systems as functional…

Mesoscale and Nanoscale Physics · Physics 2020-09-16 Jincheng Lu , Rongqian Wang , Chen Wang , Jian-Hua Jiang