A Numerical Study of Quantum Decoherence

2012 ◽  
Vol 12 (1) ◽  
pp. 85-108 ◽  
Author(s):  
Riccardo Adami ◽  
Claudia Negulescu
Keyword(s):  
Density Matrix ◽  
Particle Density ◽  
Numerical Study ◽  
Heavy Particle ◽  
Splitting Method ◽  
Time Dependent ◽  
Quantum Decoherence ◽  
Approximation Formula ◽  
Time Splitting ◽  
Decoherence Effect

AbstractThe present paper provides a numerical investigation of the decoherence effect induced on a quantum heavy particle by the scattering with a light one. The time dependent two-particle Schrödinger equation is solved by means of a time-splitting method. The damping undergone by the non-diagonal terms of the heavy particle density matrix is estimated numerically as well as the error in the Joos-Zeh approximation formula.

Static properties of the 2D Hubbard model on a 4×4 cluster

1989 ◽  
Vol 03 (12) ◽  
pp. 1865-1873 ◽  
Author(s):  
Alberto Parola ◽  
Sandro Sorella ◽  
Stefano Baroni ◽  
Michele Parrinello ◽  
Erio Tosatti
Keyword(s):  
Density Matrix ◽  
Hubbard Model ◽  
Particle Density ◽  
Numerical Study ◽  
Exact Diagonalization ◽  
Exact Results ◽  
Power Method ◽  
Static Properties ◽  
Simple Power ◽  
The One

A numerical study of the 2D Hubbard model at various fillings has been performed. The static properties of 10, 14 and 16 electrons on a 4×4 cluster have been studied by exact diagonalization at intermediate couplings. A simple “power method” has been used in order to minimize memory requirements. Spin-spin, charge-charge and hole-hole correlations have been computed together with the one particle density matrix. This computation provides the first exact results on such a system, which can be used as a test for existing simulation algorithms.

scholarly journals Integrating Semilinear Wave Problems with Time-Dependent Boundary Values Using Arbitrarily High-Order Splitting Methods

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1113
Author(s):  
Isaías Alonso-Mallo ◽  
Ana M. Portillo
Keyword(s):  
Numerical Experiments ◽  
Splitting Method ◽  
Method Of Lines ◽  
Time Integration ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
High Order ◽  
Time Dependent ◽  
Boundary Values ◽  
Lipschitz Continuous

The initial boundary-value problem associated to a semilinear wave equation with time-dependent boundary values was approximated by using the method of lines. Time integration is achieved by means of an explicit time method obtained from an arbitrarily high-order splitting scheme. We propose a technique to incorporate the boundary values that is more accurate than the one obtained in the standard way, which is clearly seen in the numerical experiments. We prove the consistency and convergence, with the same order of the splitting method, of the full discretization carried out with this technique. Although we performed mathematical analysis under the hypothesis that the source term was Lipschitz-continuous, numerical experiments show that this technique works in more general cases.

Density cumulant functional theory: The DC-12 method, an improved description of the one-particle density matrix

2013 ◽  
Vol 138 (2) ◽  
pp. 024107 ◽  
Author(s):  
Alexander Yu. Sokolov ◽  
Andrew C. Simmonett ◽  
Henry F. Schaefer
Keyword(s):  
Density Matrix ◽  
Particle Density ◽  
Functional Theory ◽  
The One

Convergence of time-splitting approximations for degenerate convection-diffusion equations with a random source

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Roberto Díaz-Adame ◽  
Silvia Jerez
Keyword(s):  
Hyperbolic Conservation Laws ◽  
Splitting Method ◽  
Diffusion Equations ◽  
Hyperbolic Conservation ◽  
Convection Diffusion ◽  
Parabolic Case ◽  
Weak Entropy Solution ◽  
Degenerate Parabolic ◽  
Time Splitting ◽  
Operator Scheme

AbstractIn this paper we propose a time-splitting method for degenerate convection-diffusion equations perturbed stochastically by white noise. This work generalizes previous results on splitting operator techniques for stochastic hyperbolic conservation laws for the degenerate parabolic case. The convergence in $\begin{array}{} \displaystyle L^p_{loc} \end{array}$ of the time-splitting operator scheme to the unique weak entropy solution is proven. Moreover, we analyze the performance of the splitting approximation by computing its convergence rate and showing numerical simulations for some benchmark examples, including a fluid flow application in porous media.

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