scholarly journals Derivation of nonlinear single-particle equations via many-body Lindblad superoperators: A density-matrix approach

2014 ◽  
Vol 90 (12) ◽  
Author(s):  
Roberto Rosati ◽  
Rita Claudia Iotti ◽  
Fabrizio Dolcini ◽  
Fausto Rossi
Keyword(s):  
Density Matrix ◽  
Single Particle ◽  
Matrix Approach ◽  
Many Body

scholarly journals A Simple Derivation of the Bloch Equations for Localized Moment E.S.R. in Metals in the Presence of Anisotropy

1973 ◽  
Vol 26 (4) ◽  
pp. 475 ◽  
Author(s):  
DA Smith
Keyword(s):  
Electron Spin Resonance ◽  
Density Matrix ◽  
Matrix Approach ◽  
Many Body ◽  
Bloch Equations ◽  
Simple Derivation ◽  
Local Moments ◽  
Conduction Electrons ◽  
Spin Resonance ◽  
Body Techniques

A density-matrix approach is used to derive the coupled Bloch equations for the electron spin resonance of localized moments and conduction electrons in metals, including anisotropy fields acting on the local moments. The equations agree with those obtained elsewhere by more sophisticated many-body techniques. In particular, it is demonstrated explicitly that relaxation proceeds towards instantaneous equilibrium.

Many‐body theory of exchange effects in intermolecular interactions. Density matrix approach and applications to He–F−, He–HF, H2–HF, and Ar–H2 dimers

1994 ◽  
Vol 100 (7) ◽  
pp. 5080-5092 ◽  
Author(s):  
Robert Moszynski ◽  
Bogumil Jeziorski ◽  
Stanislaw Rybak ◽  
Krzysztof Szalewicz ◽  
Hayes L. Williams
Keyword(s):  
Density Matrix ◽  
Intermolecular Interactions ◽  
Matrix Approach ◽  
Many Body ◽  
Many Body Theory ◽  
Exchange Effects ◽  
Body Theory

QLB for Quantum Many-Body and Quantum Field Theory

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Mechanics ◽  
Quantum Computing ◽  
Single Particle ◽  
Body Problem ◽  
Three Dimensions ◽  
Quantum Field ◽  
Many Body ◽  
Quantum Particles

Chapter 32 expounded the basic theory of quantum LB for the case of relativistic and non-relativistic wavefunctions, namely single-particle quantum mechanics. This chapter goes on to cover extensions of the quantum LB formalism to the overly challenging arena of quantum many-body problems and quantum field theory, along with an appraisal of prospective quantum computing implementations. Solving the single particle Schrodinger, or Dirac, equation in three dimensions is a computationally demanding task. This task, however, pales in front of the ordeal of solving the Schrodinger equation for the quantum many-body problem, namely a collection of many quantum particles, typically nuclei and electrons in a given atom or molecule.

scholarly journals Feynman diagrams and rooted maps

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 149-167 ◽  
Author(s):  
Andrea Prunotto ◽  
Wanda Maria Alberico ◽  
Piotr Czerski
Keyword(s):  
Single Particle ◽  
Feynman Diagram ◽  
Feynman Diagrams ◽  
Topological Properties ◽  
Many Body ◽  
Perturbative Order ◽  
Original Definition ◽  
Many Body Systems ◽  
Definition Of ◽  
Particle Propagator

Abstract The rooted maps theory, a branch of the theory of homology, is shown to be a powerful tool for investigating the topological properties of Feynman diagrams, related to the single particle propagator in the quantum many-body systems. The numerical correspondence between the number of this class of Feynman diagrams as a function of perturbative order and the number of rooted maps as a function of the number of edges is studied. A graphical procedure to associate Feynman diagrams and rooted maps is then stated. Finally, starting from rooted maps principles, an original definition of the genus of a Feynman diagram, which totally differs from the usual one, is given.

Few-Particle Effects in Nonlinear Optical Spectra of Semiconductor Quantum Dots

1999 ◽  
Vol 571 ◽  
Author(s):  
Ulrich Hohenesteri ◽  
Fausto Rossi ◽  
Elisa Molinari
Keyword(s):  
Quantum Dots ◽  
Density Matrix ◽  
Nonlinear Optical ◽  
Coherent Control ◽  
Optical Spectra ◽  
Carrier Dynamics ◽  
Semiconductor Quantum Dots ◽  
Nonequilibrium Carrier ◽  
Optical Nonlinearities ◽  
Matrix Approach

ABSTRACTWe present a density-matrix approach for the description of nonequilibrium carrier dynamics in optically excited semiconductor quantum dots, that explicitly accounts for exciton-exciton as well as exciton-carrier interactions. Within this framework, we analyze few-particle effects in the optical spectra and provide a consistent description of additional peaks appearing at high photoexcitation density. We discuss possible applications of such optical nonlinearities in future coherent-control experiments.

A SOLVABLE MODEL OF INTERACTING MANY BODY SYSTEMS EXHIBITING A BREAKDOWN OF THE BOLTZMANN EQUATION

2014 ◽  
Vol 28 (03) ◽  
pp. 1450046
Author(s):  
B. H. J. McKELLAR
Keyword(s):  
Boltzmann Equation ◽  
Time Dependence ◽  
Single Particle ◽  
Density Operator ◽  
Particle Density ◽  
Solvable Model ◽  
Many Body ◽  
Single Particle Density ◽  
The Boltzmann Equation ◽  
Many Body Systems

In a particular exactly solvable model of an interacting system, the Boltzmann equation predicts a constant single particle density operator, whereas the exact solution gives a single particle density operator with a nontrivial time dependence. All of the time dependence of the single particle density operator is generated by the correlations.

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