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We propose a method to obtain the thermal-equilibrium density matrix of a many-body quantum system using artificial neural networks. The variational function of the many-body density matrix is represented by a convolutional neural network…

Disordered Systems and Neural Networks · Physics 2020-03-18 Naoki Irikura , Hiroki Saito

We study wormhole as the solution of the Wheeler-deWitt (WdW ) equation satisfying Hawking-Page wormhole boundary conditions in Friedmann-Robertson-Walker (FRW) cosmology. The quantum wormholes are formulated with arbitrary factor ordering…

General Relativity and Quantum Cosmology · Physics 2025-11-18 Farook Rahaman , Bikramarka S. Choudhury , Anikul Islam

The quantum dynamics of electron-nuclear systems is analyzed from the perspective of the exact factorization of the wavefunction, with the aim of defining gauge invariant equations of motion for both the nuclei and the electrons. For pure…

Chemical Physics · Physics 2023-10-16 Rocco Martinazzo , Irene Burghardt

We present a simple derivation of the Hellmann-Feynman theorem at finite temperature. We illustrate its validity by considering three relevant examples which can be used in quantum mechanics lectures: the one-dimensional harmonic…

Quantum Physics · Physics 2020-06-24 Marina Pons , Bruno Juliá-Díaz , Arnau Rios , Isaac Vidaña , Artur Polls

In present paper the Quantum Electrodynamics theory at finite temperatures for the bound states is presented. To describe the thermal effects arising in a heat bath the Hadamard form of thermal photon propagator is employed. This form…

Atomic Physics · Physics 2020-03-24 D. Solovyev

A computational scheme is developed to determine the response of a quantum field theory (QFT) with a factorized scattering operator under a variation of the Unruh temperature. To this end a new family of integrable systems is introduced,…

High Energy Physics - Theory · Physics 2009-10-31 M. R. Niedermaier

We address the dephasing dynamics of a qubit as an effective process to estimate the temperature of its environment. Our scheme is inherently quantum, since it exploits the sensitivity of the qubit to decoherence, and does not require…

In this paper it is studied the cosmology of a homogeneous and isotropic spacetime endorsed with a conformally coupled massless scalar field. We find six different solutions of the Friedmann equation that represent six different types of…

General Relativity and Quantum Cosmology · Physics 2017-09-20 Salvador J. Robles-Perez

We study the non-equilibrium dynamics of the Luttinger model after a quantum quench, when the initial state is a finite temperature thermal equilibrium state. The diagonal elements of the density matrix in the steady state show thermal…

Strongly Correlated Electrons · Physics 2013-10-16 Ádám Bácsi , Balázs Dóra

The thermodynamics of quantum systems driven out of equilibrium has attracted increasing attention in last the decade, in connection with quantum information and statistical physics, and with a focus on non-classical signatures. While a…

Quantum Physics · Physics 2022-06-01 Gonzalo Manzano , Roberta Zambrini

Wheeler-DeWitt equation is applied to $k > 0$ Friedmann Robertson Walker metric with various types of matter. It is shown that if the Universe ends in the matter dominated era (e.g., radiation or pressureless gas) with zero cosmological…

High Energy Physics - Theory · Physics 2010-11-01 Jong Hyun Kung

A way to address the conundrum of Quantum Gravity is to illustrate the potentially fundamental interplay between quantum field theory, curved space-times physics and thermodynamics. So far, when studying moving quantum systems in the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Nathaniel Obadia

We consider the Di\'osi-Penrose problem but rather than postulating background gravitational fluctuations, we instead consider the quantum filter that arises from space-time homodyning the continuum of output quadrature described in the…

Quantum Physics · Physics 2026-04-29 John Gough , Dylon Rees

An exact stochastic model for the thermalisation of quantum states is proposed. The model has various physically appealing properties. The dynamics are characterised by an underlying Schrodinger evolution, together with a nonlinear term…

Quantum Physics · Physics 2009-10-30 D. C. Brody , L. P. Hughston

The equations of time-dependent density functional theory are derived, via the expression for the quantum weak value, from ring polymer quantum theory using a symmetry between time and imaginary time. The imaginary time path integral…

Quantum Physics · Physics 2025-03-21 Russell B. Thompson , Zarin Tasneem , Yves Caudano

Wave-function methods have offered a robust, systematically improvable means to study ground-state properties in quantum many-body systems. Theories like coupled cluster and their derivatives provide highly accurate approximations to the…

Strongly Correlated Electrons · Physics 2023-05-10 Gaurav Harsha , Thomas M. Henderson , Gustavo E. Scuseria

We study the heat statistics of a multi-level $N$-dimensional quantum system monitored by a sequence of projective measurements. The late-time, asymptotic properties of the heat characteristic function are analyzed in the thermodynamic…

Quantum Physics · Physics 2021-09-15 Stefano Gherardini , Guido Giachetti , Stefano Ruffo , Andrea Trombettoni

The Schwinger model at finite temperature is analyzed using the Thermofield Dynamics formalism. The operator solution due to Lowenstein and Swieca is generalized to the case of finite temperature within the thermofield bosonization…

High Energy Physics - Theory · Physics 2010-12-13 L. V. Belvedere , R. L. P. G. Amaral , K. D. Rothe , A. F. Rodrigues

A stationary theory of quantum stochastic processes of second order is outlined. It includes KMS processes in wide sense like the equilibrium finite temperature quantum noise given by the Planck's spectral formula. It is shown that for each…

Quantum Physics · Physics 2014-11-18 V. P. Belavkin , O. Hirota , R. Hudson

Toward the formulation of the operational approach to quantum thermodynamics, the heat-up operator is explicitly constructed. This quantum operation generates for a generic system an irreversible transformation from a pure ground state at…

Statistical Mechanics · Physics 2010-10-07 Mozhgan Sabzehzari , Yuki Aoyaghi , Sumiyoshi Abe