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We study the time evolution of correlation functions in closed quantum systems for nonequilibrium ensembles of initial conditions. For a scalar quantum field theory we show that generic time-reversal invariant evolutions approach…

High Energy Physics - Phenomenology · Physics 2010-02-04 J. Berges , J. Cox

The time evolution of an extended quantum system can be theoretically described in terms of the Schwinger-Keldysh functional integral formalism, whose action conveniently encodes the information about the dynamics. We show here that the…

Statistical Mechanics · Physics 2015-11-11 L. M. Sieberer , A. Chiocchetta , A. Gambassi , U. C. Täuber , S. Diehl

In this paper we describe a new model for solidification with heat flux using the phase field crystal (PFC) framework. The equations are thermodynamically consistent, in the sense that the time rate of change of the entropy density is…

Materials Science · Physics 2021-07-13 C. Wang , S. M. Wise

We present a finite-temperature extension of density matrix embedding theory (FT-DMET) for realistic crystalline systems. We describe a practical framework for constructing extended bath orbitals, solving the embedding problem, and…

Computational Physics · Physics 2026-01-06 Laurence Giordano , Y. Stanley Tan , Zhi-Hao Cui , Chong Sun

Noncommutative phase-space and its effects have been studied in different settings in physics, in order to unveil a better understanding of phase-space structures. Here, we use the thermal diffusion approach to study how noncommutative…

Quantum Physics · Physics 2019-09-16 Jonas F. G. Santos

We study the time evolution of a single qubit in contact with a bath, within the framework of projection operator methods. Employing the so-called modified Redfield theory which also treats energy conserving interactions non-perturbatively,…

Statistical Mechanics · Physics 2024-06-10 Jiaozi Wang , Jochen Gemmer

Dynamical evolution of the quantum ground state (vacuum) is analyzed for time variant harmonic oscillators characterized by asymptotically constant frequency. The oscillatory density matrix in the asymptotic future is uniquely determined by…

High Energy Physics - Theory · Physics 2007-05-23 M. Yoshimura

The heat-kernel expansion and $\zeta$-regularization techniques for quantum field theory and extended objects on curved space-times are reviewed. In particular, ultrastatic space-times with spatial section consisting in manifold with…

High Energy Physics - Theory · Physics 2011-08-17 A. A. Bytsenko , G. Cognola , L. Vanzo , S. Zerbini

In this work, we consider a two level $P\sigma_{z}$ pseudo-Hermitian system in contact with a thermal bath to study various thermodynamic properties. The system is realized in terms of infinitely many invariant subspaces. We find explicit…

Quantum Physics · Physics 2025-03-25 Gargi Das , Bhabani Prasad Mandal

One of the fundamental problems of quantum statistical physics is how an ideally isolated quantum system can ever reach thermal equilibrium behavior despite the unitary time evolution of quantum-mechanical systems. Here, we study, via…

Quantum Physics · Physics 2025-06-24 Marvin Lenk , Sayak Biswas , Anna Posazhennikova , Johann Kroha

We propose a general extended coherent state approach to the qubit (or fermion) and multi-mode boson coupling systems. The application to the spin-boson model with the discretization of a bosonic bath with arbitrary continuous spectral…

Quantum Gases · Physics 2015-05-14 Yu-Yu Zhang , Qing-Hu Chen , Ke-Lin Wang

Time-evolution of the Universe as described by the Friedmann equation can be coupled to equations of motion of matter fields. Quantum effects may be incorporated to improve these classical equations of motion by the renormalization group…

High Energy Physics - Theory · Physics 2024-10-08 Istvan Gabor Marian , Andrea Trombettoni , Istvan Nandori

Conventional phase-field models often drive solid-solid interfaces to coalesce when in close proximity. This feature limits their use for processes like diffusion bonding, where the interfaces might need to remain distinct under certain…

Materials Science · Physics 2026-02-20 Maryam Khodadad , Noel Walkington , Suresh Kalyanam , Matteo Pozzi , Kaushik Dayal

We introduce a group-theoretical extension of the Dicke model which describes an ensemble of two-level atoms interacting with a finite radiation field. The latter is described by a spin model whose main feature is that it possesses a…

Quantum Physics · Physics 2020-06-17 L. F. Quezada , A. Martín-Ruiz , A. Frank

We investigate the evolution of a target qubit caused by its multiple random collisions with $N$-qubit clusters. Depending on the cluster state, the evolution of the target qubit may correspond to its effective interaction with a thermal…

We introduce a nonperturbative, first-principles approach to time-dependent problems in quantum field theory. In this approach, the time-evolution of quantum field configurations is calculated in real time and at the amplitude level. This…

Nuclear Theory · Physics 2015-06-18 Xingbo Zhao , Anton Ilderton , Pieter Maris , James P. Vary

We investigate the thermodynamical properties of quantum fields in curved spacetime. Our approach is to consider quantum fields in curved spacetime as a quantum system undergoing an out-of-equilibrium transformation. The non-equilibrium…

Quantum Physics · Physics 2016-01-14 Nana Liu , John Goold , Ivette Fuentes , Vlatko Vedral , Kavan Modi , David Edward Bruschi

Generalized Hydrodynamics (GHD) has recently been devised as a method to solve the dynamics of integrable quantum many-body systems beyond the mean-field approximation. In its original form, a major limitation is the inability to predict…

The generalized amplitude damping (GAD) quantum channel implements the interaction between a qubit and an environment with arbitrary temperature and arbitrary interaction time. Here, we implement a photonic version of the GAD for the case…

We argue that macroscopic electrodynamics is unsuited to describe the process of radiative thermalization between a levitated nanoparticle in high vacuum and the thermal electromagnetic field. Based on physical arguments, we propose a model…

Quantum Physics · Physics 2018-10-10 Adrian E. Rubio Lopez , Carlos Gonzalez-Ballestero , Oriol Romero-Isart