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A nonperturbative theory is developed, aiming at an exact and efficient evaluation of a general quantum system interacting with arbitrary bath environment at any temperature and in the presence of arbitrary time-dependent external fields.…

Statistical Mechanics · Physics 2007-05-23 Rui-Xue Xu , YiJing Yan

Consistent dynamics which couples classical and quantum degrees of freedom exists, provided it is stochastic. This dynamics is linear in the hybrid state, completely positive and trace preserving. One application of this is to study the…

Quantum Physics · Physics 2023-01-04 Jonathan Oppenheim , Carlo Sparaciari , Barbara Šoda , Zachary Weller-Davies

We study the back-reaction of quantum systems onto classical ones. Taking the starting point that semi-classical physics should be described at all times by a point in classical phase space and a quantum state in Hilbert space, we consider…

Quantum Physics · Physics 2024-12-18 Isaac Layton , Jonathan Oppenheim , Zachary Weller-Davies

A description of the motion in noninertial reference frames by means of the inclusion of high time derivatives is studied. Incompleteness of the description of physical reality is a problem of any theory, both in quantum mechanics and…

General Physics · Physics 2020-01-01 Timur F. Kamalov

We present a fully covariant transport framework for Molecular Dynamics that enables a consistent description of the evolution of relativistic N-body systems. For the first time, we derive relativistic equations of motion incorporating both…

Nuclear Theory · Physics 2025-11-19 Jiaxing Zhao , Joerg Aichelin , Elena Bratkovskaya

Models that provide experimentally testable violations of ordinary Quantum Mechanics have been recently proposed. These models are based on non-unitary time evolutions of density matrices that are generated by linear positive maps. We…

High Energy Physics - Theory · Physics 2009-10-30 F. Benatti , R. Floreanini

In principle, non-Hermitian quantum equations of motion can be formulated using as a starting point either the Heisenberg's or the Schr\"odinger's picture of quantum dynamics. Here it is shown in both cases how to map the algebra of…

Quantum Physics · Physics 2011-02-07 Alessandro Sergi

Equations of motion that recognize biochemical patterns are described. The equations are partial differential equations in a continuous multiple component system in which adequate initial and boundary conditions are given. The biochemical…

Biological Physics · Physics 2010-03-25 Eisuke Chikayama

We derive the renormalized nonequilibrium equations of motion for a scalar field and its quantum back reaction in a conformally flat Friedmann-Robertson-Walker universe. We use a fully covariant formalism proposed by us recently for…

High Energy Physics - Phenomenology · Physics 2014-11-17 Jurgen Baacke , Katrin Heitmann , Carsten Patzold

We investigate the relationship between strict positivity of the Kossakowski matrix, irreducibility and positivity improvement properties of Markovian Quantum Dynamics. We show that for a Gaussian quantum dynamical semigroup strict…

Quantum Physics · Physics 2025-04-01 Julián Agredo , Franco Fagnola , Damiano Poletti

We outline an approach that streamlines considerably the construction and analysis of well-behaved nonlinear quantum dynamics, with completely positive extensions to entangled systems. A few notes are added on the issue of quantum…

Quantum Physics · Physics 2007-05-23 S. Gheorghiu-Svirschevski

It is argued that in the description of macroscopic systems inside quantum mechanics the study of the dynamics of selected degrees of freedom slowly varying on a suitable time scale, corresponding to relevant observables for the given…

Quantum Physics · Physics 2007-05-23 B. Vacchini

We provide a general construction of quantum generalized master equations with memory kernel leading to well defined, that is completely positive and trace preserving, time evolutions. The approach builds on an operator generalization of…

Quantum Physics · Physics 2016-12-15 Bassano Vacchini

The vast majority of the literature dealing with quantum dynamics is concerned with linear evolution of the wave function or the density matrix. A complete dynamical description requires a full understanding of the evolution of measured…

We present a general methodology for addressing the infinite hierarchy problem that arises in measurement-induced dynamics of replicated quantum systems. Our approach introduces trace-preserving replica cutoffs using tomographic-like…

Quantum Physics · Physics 2025-04-02 Graham Kells

We study the concepts of complete positivity, positivity and non-Markovianity in a two-level open quantum system whose dynamics are governed by a time-local quantum master equation. We establish necessary and sufficient conditions on the…

Quantum Physics · Physics 2023-12-27 G. Théret , D. Sugny

By modeling the interaction of a system with an environment through a renewal approach, we demonstrate that completely positive non-Markovian dynamics may develop some unexplored non-standard statistical properties. The renewal approach is…

Quantum Physics · Physics 2009-08-07 Adrian A. Budini Paolo Grigolini

We compute explicitly the equations of motion of the Hamiltonian formulation of quadratic gravity. This is the theory with the most general Lagrangian with terms of quadratic order in the curvature tensor. We employ the symbolic…

General Relativity and Quantum Cosmology · Physics 2026-03-13 Jorge Bellorin

Whether gravity must be quantized remains one of the biggest open problems in fundamental physics. Classical-quantum hybrid theories have recently attracted attention as a possible framework in which gravity is treated classically yet…

Quantum Physics · Physics 2026-04-14 Masahiro Hotta , Sebastian Murk , Daniel R. Terno

Simple Hartree-type equations lead to dynamics of a subsystem that is not completely positive in the sense accepted in mathematical literature. In the linear case this would imply that negative probabilities have to appear for some system…

Quantum Physics · Physics 2009-10-30 Marek Czachor , Maciej Kuna