scholarly journals Coupled quantum oscillators within independent quantum reservoirs

2013 ◽  
Vol 91 (7) ◽  
pp. 537-541 ◽  
Author(s):  
Illarion Dorofeyev
Keyword(s):  
Open Quantum Systems ◽  
Equations Of Motion ◽  
Dissipative Systems ◽  
Langevin Equations ◽  
Coupling Constant ◽  
Nonmonotonic Dependence ◽  
Model Hamiltonian ◽  
Heisenberg Equations ◽  
Energy Of Interaction ◽  
Analytical Expressions

This paper addresses the problem of open quantum systems. The energy of interaction of coupled dissipative systems is the main focus of the study. Quantum Langevin equations for two quantum coupling oscillators within independent heat baths of quantum oscillators are obtained using a model Hamiltonian and corresponding Heisenberg equations of motion. Analytical expressions for mean energy of coupled oscillators and their mean energy of interaction are derived and analyzed. Nonmonotonic dependence of the interaction energy versus a coupling constant is demonstrated and an explanation is suggested.

Wigner Distribution Function for Open Quantum Systems

1997 ◽  
Vol 11 (09n10) ◽  
pp. 391-397 ◽  
Author(s):  
S. Baskoutas
Keyword(s):  
Distribution Function ◽  
Degrees Of Freedom ◽  
Wigner Distribution ◽  
Open Quantum Systems ◽  
Equations Of Motion ◽  
Analytical Form ◽  
Dissipative Systems ◽  
Wigner Distribution Function ◽  
Dissipative Tunneling ◽  
Lie Algebraic Structure

Using the modified biorthonormal Heisenberg equations of motion for non-Hermitian (NH) Hamilton operators, in order to imply a consistent Lie-algebraic structure and also the equivalence between the Heisenberg and Schrödinger pictures, we have obtained the analytical form of the Wigner distribution function which is unavoidable complex. Its imaginary part accounts for the influence of additional degrees of freedom, which are always present in the phenomenological representation of dissipative systems through (NH) Hamiltonians. Applications of the above formalism can be found, for instance, in dissipative macroscopic quantum tunneling (MQT) effect for Josephson junctions, and in the dissipative tunneling of trapped atoms in optical crystals.

scholarly journals The Problem of Engines in Statistical Physics

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 1095
Author(s):  
Robert Alicki ◽  
David Gelbwaser-Klimovsky ◽  
Alejandro Jenkins
Keyword(s):  
Statistical Physics ◽  
Degrees Of Freedom ◽  
Open Systems ◽  
Open Quantum Systems ◽  
Equations Of Motion ◽  
Blind Spot ◽  
Langevin Equations ◽  
External Loading ◽  
Realistic Description ◽  
Irreversible Dynamics

Engines are open systems that can generate work cyclically at the expense of an external disequilibrium. They are ubiquitous in nature and technology, but the course of mathematical physics over the last 300 years has tended to make their dynamics in time a theoretical blind spot. This has hampered the usefulness of statistical mechanics applied to active systems, including living matter. We argue that recent advances in the theory of open quantum systems, coupled with renewed interest in understanding how active forces result from positive feedback between different macroscopic degrees of freedom in the presence of dissipation, point to a more realistic description of autonomous engines. We propose a general conceptualization of an engine that helps clarify the distinction between its heat and work outputs. Based on this, we show how the external loading force and the thermal noise may be incorporated into the relevant equations of motion. This modifies the usual Fokker–Planck and Langevin equations, offering a thermodynamically complete formulation of the irreversible dynamics of simple oscillating and rotating engines.

scholarly journals Perturbation Analysis of Quantum Reset Models

2021 ◽  
Vol 183 (1) ◽  
Author(s):  
Géraldine Haack ◽  
Alain Joye
Keyword(s):  
Steady State ◽  
Perturbation Analysis ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Markov Semigroup ◽  
Coupling Constant ◽  
Coupling Term ◽  
Open Quantum ◽  
Effective Dynamics ◽  
A Chain

AbstractThis paper is devoted to the analysis of Lindblad operators of Quantum Reset Models, describing the effective dynamics of tri-partite quantum systems subject to stochastic resets. We consider a chain of three independent subsystems, coupled by a Hamiltonian term. The two subsystems at each end of the chain are driven, independently from each other, by a reset Lindbladian, while the center system is driven by a Hamiltonian. Under generic assumptions on the coupling term, we prove the existence of a unique steady state for the perturbed reset Lindbladian, analytic in the coupling constant. We further analyze the large times dynamics of the corresponding CPTP Markov semigroup that describes the approach to the steady state. We illustrate these results with concrete examples corresponding to realistic open quantum systems.

On the constant of motion of dissipative systems

2002 ◽  
Vol 80 (1) ◽  
pp. 1-5 ◽  
Author(s):  
A Patiño ◽  
H Rago
Keyword(s):  
Harmonic Oscillator ◽  
Equations Of Motion ◽  
Viscous Medium ◽  
Dissipative Systems ◽  
Damped Harmonic Oscillator ◽  
Constant Of Motion

We apply results on symmetries of equations of motion and equivalent Lagrangians to obtain a constant of motion for a particle travelling through a viscous medium and for the damped harmonic oscillator. PACS No.: 45.20Jj

scholarly journals ANISOTROPIC NULL STRING COSMOLOGIES

1998 ◽  
Vol 13 (39) ◽  
pp. 3169-3177 ◽  
Author(s):  
IOANNIS GIANNAKIS ◽  
K. KLEIDIS ◽  
A. KUIROUKIDIS ◽  
D. PAPADOPOULOS
Keyword(s):  
Equations Of Motion ◽  
String Tension ◽  
Perturbative Expansion ◽  
Speed Of Light ◽  
Zeroth Order ◽  
First Order ◽  
Cosmological Background ◽  
String Propagation ◽  
Analytical Expressions ◽  
Null String

We study string propagation in an anisotropic, cosmological background. We solve the equations of motion and the constraints by performing a perturbative expansion of the string coordinates in powers if c2 — the worldsheet speed of light. To zeroth order the string is approximated by a tensionless string (since c is proportional to the string tension T). We obtain exact, analytical expressions for the zeroth- and first-order solutions and we discuss some cosmological implications.

scholarly journals Exact density matrix elements for a driven dissipative system described by a quadratic Hamiltonian

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sh. Saedi ◽  
F. Kheirandish
Keyword(s):  
Density Matrix ◽  
Equations Of Motion ◽  
Dissipative System ◽  
Characteristic Functions ◽  
Matrix Elements ◽  
Exact Density ◽  
Quadratic Hamiltonian ◽  
Heisenberg Equations ◽  
Reduced Density ◽  
Heisenberg Equations Of Motion

AbstractFor a prototype quadratic Hamiltonian describing a driven, dissipative system, exact matrix elements of the reduced density matrix are obtained from a generating function in terms of the normal characteristic functions. The approach is based on the Heisenberg equations of motion and operator calculus. The special and limiting cases are discussed.

Heisenberg equations of motion in the Caldirola-Montaldi procedure

1982 ◽  
Vol 67 (2) ◽  
pp. 161-172 ◽  
Author(s):  
A. Jannussis ◽  
A. Leodaris ◽  
P. Filippakis ◽  
Th. Filippakis ◽  
V. Zisis
Keyword(s):  
Equations Of Motion ◽  
Heisenberg Equations ◽  
Heisenberg Equations Of Motion
Sign in / Sign up

Export Citation Format

Share Document