Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

AIP conference proceedings

Expectation Matrix Based Quantum Dynamics of a Univariate System at the Zero Fluctuation Limit

Metin Demіralp, Theodore E. Simos, George Maroulis

Published Jan 1, 2007• 0 citations
Publisher

Abstract

The variation of the expectation matrix of position and momentum operator in time can serve us to investigate the evolution of a quantum system in time. This brings the utilization of the ODEs instead of Schrödinger's equation at the expense of incapability for the calculation of the wave function. As long as we deal with the observables which can be expressed in terms of position and momentum operators this may be quite practical to know about the quantum dynamics of the system under consideration. Expectation matrix of an operator becomes a function of the expectation matrices of the position and momentum operator when the fluctuations diminish to zero. At this limit, the time‐variant ODEs for the expectation matrices of the position and momentum operator can be handled by using the matrix algebraic tools even in the case of nonlinearities in the potential function. This work presents certain details about these points.

DOI
10.1063/1.2835957

Related papers

Approximation methods for the solution of quantum evolution equations at the zero fluctuation limit

Buket Benek, Metin Demіralp

This paper is focused on the solution of a univariate quantum dynamical system that can be treated through the dynamics of expectation values of the position and momentum operators. This goal is realised by using the fluctuationlessness theorem. The concerned equations are matrix equations and derived using the wave function of the Schrodinger equation. The quality of the obtained approximated solution is tested by comparing it with the real solution for different n values.

•May 27, 2008•0 citations

Phase Space Consideration in Quantum Dynamical Fluctuation Expansion

Esma Meral, Metin Demіralp

A new method called “Fluctuation Expansion” has been recently proposed for solving quantum dynamical problems . This method is succesfully applied to the dynamics of expectation values such that not the wave function itself but the expectation values of the position and momentum operator are taken into consideration and then the expectation value of certain entities depending on position and momentum operators are expressed via fluctuation expansion. This brings an infinite number of new unknown, fundamental and associate fluctuation terms. The derivatives of expectation values of the position and momentum operators and fluctuation operators are expressed in terms of these terms again. The resulting infinite set of differential equations and accompanying initial conditions are truncated at certain fluctuation order and then tried to be solved. Here we take a one dimensional time independent Hamiltonian and consider the zeroth and first order truncations. Equations obtained in this way are investigated in the sense of phase space which is defined by the expextation values of the position and momentum operator and the fluctuations entering the truncated equations. We find certain subspaces of the phase space such that there, certain expressions remain constant . This helps us to reduce the dimension of the problem.

CRC Press eBooks•May 4, 2022•0 citations

A Fluctuation Analysis at the Classical Limit for the Expectation Dynamics of a Single Quartic Quantum Anharmonic Oscillator

Muzaffer Ayvaz, Metin Demіralp, Theodore E. Simos +2 more

The definition of the fluctuation terms in the matrix representations of operators, especially function operators, brings a lot of facilitations to the numerical analysis of matrix representation issues. This work considers a one‐dimensional quantum oscillator with purely quartic anharmonicity and focuses on its position and momentum expectations. By using certain level commutator operation it is possible to get two ODEs as equations of motion, which are in classical nature when the fluctuation terms are omitted. To understand how fluctuation terms affect expectation dynamical analysis we add extra temporal unknowns and construct extra ODEs over them. There seem to be an infinite ODEs chain for fluctuation altough their truncations seem to be utilizable as approximations. Here basic theory is summarized. Further details will be prasented at the conference presentation.

AIP conference proceedings•Jan 1, 2010•2 citations

Utilization of the fluctuationlessness theorem in the evaluation of certain operator matrix representations for optimally controlled simple quantum harmonic oscillator

Muzaffer Ayvaz, Metin Demіralp

Recent years brought a new angle of view to the problems involving matrix representations of, especially, functions. It is the utilization of the fuctuation free matrix representation of those functions, where the matrix representation of the function is taken as the image of the matrix representation of the independent variable under the concerned function as a first approximation. The quality of the approximation becomes better as the fluctuations are suppressed by changing the subspace dimension under consideration. In this study, we discuss the quantum optimal control problem of simple harmonic oscillator as a first step towards the construction of possibly an efficient new tool. Here, the expectation value based optimal control equations are formulated and the all agents of the problem are taken linear for simplicity. The resultant linear system of ordinary differantial equations have exact solutions. By using these solutions and the fluctuationlessness approximation, it is possible to evaluate the matrix representation of an analytic function of the position and momentum operators.

•May 27, 2008•5 citations

Determination of Quantum Expectation Values Via Fluctuation Expansion

Metin Demіralp

The goal of this work is, the utilization of a method recently developed by the author, in quantum dynamical problems. Main idea is based on the relation between quantum and classical dynamics such that quantum dynamical problems become their classical dynamical counterparts when they are formulated via expectation values of certain operators and the probability density tends to be sharply localized. Expectation values can be expanded into a series in ascending appearence multiplicity of the complement of the projection operator which projects the space spanned by the wave function. This expansion contains fluctuation terms as unknowns besides the expectation values. We construct an infinite set of differential equations. The finite truncations of this set enables us to approximate the quantum dynamics of the system under consideration.

CRC Press eBooks•May 4, 2022•2 citations

Energetic fluctuation expansion in quantum evolvers dynamics from the new extended form of probabilistic evolution theoretical (PREVTH) perspective

Berfin Kalay

This paper is about the Quantum Evolver Dynamics which is based  on the Poisson Bracket algebra over the basic quantum operators for a univariate system whose potential function is analytic or  at most having polar singularity with a finite multiplicity in  the position operator. Paper is devoted to the formulation of  the evolver (temporally varying operator describing the evolution of a given operator) dynamics. The basic aim is to expand any given evolver to a fluctuation expansion with respect to the fluctuation in the Hamiltonian of the system. We reveal the relation of this (energetic) fluctuation expansion coefficient operators with the probabilistic evolution theoretical telescopic Kronecker power series which have been quite recently extended pretty much, for the isolated systems. Paper does not contain any illustration because of the concreteness in what we have developed here.

Journal | MESA•May 27, 2018•0 citations
The variation of the expectation matrix of position and momentum operator in time can serve us to investigate the evolution of a quantum system in time. This brings the utilization of the ODEs instead of Schrödinger's equation at the expense of incapability for the calculation of the wave function. As long as we deal with the observables which can be expressed in terms of position and momentum operators this may be quite practical to know about the quantum dynamics of the system under consideration. Expectation matrix of an operator becomes a function of the expectation matrices of the position and momentum operator when the fluctuations diminish to zero. At this limit, the time‐variant ODEs for the expectation matrices of the position and momentum operator can be handled by using the matrix algebraic tools even in the case of nonlinearities in the potential function. This work presents certain details about these points.
A new method called “Fluctuation Expansion” has been recently proposed for solving quantum dynamical problems . This method is succesfully applied to the dynamics of expectation values such that not the wave function itself but the expectation values of the position and momentum operator are taken into consideration and then the expectation value of certain entities depending on position and momentum operators are expressed via fluctuation expansion. This brings an infinite number of new unknown, fundamental and associate fluctuation terms. The derivatives of expectation values of the position and momentum operators and fluctuation operators are expressed in terms of these terms again. The resulting infinite set of differential equations and accompanying initial conditions are truncated at certain fluctuation order and then tried to be solved. Here we take a one dimensional time independent Hamiltonian and consider the zeroth and first order truncations. Equations obtained in this way are investigated in the sense of phase space which is defined by the expextation values of the position and momentum operator and the fluctuations entering the truncated equations. We find certain subspaces of the phase space such that there, certain expressions remain constant . This helps us to reduce the dimension of the problem.
The definition of the fluctuation terms in the matrix representations of operators, especially function operators, brings a lot of facilitations to the numerical analysis of matrix representation issues. This work considers a one‐dimensional quantum oscillator with purely quartic anharmonicity and focuses on its position and momentum expectations. By using certain level commutator operation it is possible to get two ODEs as equations of motion, which are in classical nature when the fluctuation terms are omitted. To understand how fluctuation terms affect expectation dynamical analysis we add extra temporal unknowns and construct extra ODEs over them. There seem to be an infinite ODEs chain for fluctuation altough their truncations seem to be utilizable as approximations. Here basic theory is summarized. Further details will be prasented at the conference presentation.
Recent years brought a new angle of view to the problems involving matrix representations of, especially, functions. It is the utilization of the fuctuation free matrix representation of those functions, where the matrix representation of the function is taken as the image of the matrix representation of the independent variable under the concerned function as a first approximation. The quality of the approximation becomes better as the fluctuations are suppressed by changing the subspace dimension under consideration. In this study, we discuss the quantum optimal control problem of simple harmonic oscillator as a first step towards the construction of possibly an efficient new tool. Here, the expectation value based optimal control equations are formulated and the all agents of the problem are taken linear for simplicity. The resultant linear system of ordinary differantial equations have exact solutions. By using these solutions and the fluctuationlessness approximation, it is possible to evaluate the matrix representation of an analytic function of the position and momentum operators.
The goal of this work is, the utilization of a method recently developed by the author, in quantum dynamical problems. Main idea is based on the relation between quantum and classical dynamics such that quantum dynamical problems become their classical dynamical counterparts when they are formulated via expectation values of certain operators and the probability density tends to be sharply localized. Expectation values can be expanded into a series in ascending appearence multiplicity of the complement of the projection operator which projects the space spanned by the wave function. This expansion contains fluctuation terms as unknowns besides the expectation values. We construct an infinite set of differential equations. The finite truncations of this set enables us to approximate the quantum dynamics of the system under consideration.
This paper is about the Quantum Evolver Dynamics which is based  on the Poisson Bracket algebra over the basic quantum operators for a univariate system whose potential function is analytic or  at most having polar singularity with a finite multiplicity in  the position operator. Paper is devoted to the formulation of  the evolver (temporally varying operator describing the evolution of a given operator) dynamics. The basic aim is to expand any given evolver to a fluctuation expansion with respect to the fluctuation in the Hamiltonian of the system. We reveal the relation of this (energetic) fluctuation expansion coefficient operators with the probabilistic evolution theoretical telescopic Kronecker power series which have been quite recently extended pretty much, for the isolated systems. Paper does not contain any illustration because of the concreteness in what we have developed here.