Semiclassical study of the optimal control of molecular rotors in tilted fields

Abstract. Advances towards the active manipulation of the quantum state of material system using laser pulses is offering the opportunity for progress towards a quantum information age. A broad set of powerful iterative numerical procedures has being developed within the framework of the Mathematica...

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Autores:: Guerrero Mancilla, Rubén Darío

Tipo de recurso:: Doctoral thesis

Fecha de publicación:: 2016

Institución:: Universidad Nacional de Colombia

Repositorio:: Universidad Nacional de Colombia

Idioma:: spa

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Summary:	Abstract. Advances towards the active manipulation of the quantum state of material system using laser pulses is offering the opportunity for progress towards a quantum information age. A broad set of powerful iterative numerical procedures has being developed within the framework of the Mathematical quantum control (QOC) theory having as a common goal of design, producing optimal pulse shapes capable of steer the quantum dynamics of an initial state towards a predetermined target state within a time of propagation that is predetermined too. All the formerly mentioned QOC procedures have in common that the convergence of the iterative procedure is conditioned to have non-zero overlap between the evolution of the initial state and the target at some point during the prescribed propagation time. Therefore, in order to guarantee the convergence of the optimization of the pulse, the initial guess for the optimal field should be chosen as a constant field of very high optical intensity. In summary all the iterative procedures for QOC have the following flaws: 1) The iterative procedure produces a discretization of the optimal pulse, therefore the resulting pulse shapes have the character of being proof of principle experiments that not necessarily have an experimental realm. 2) The results of the theorems regarding the existence of optimal controllers are limited to systems of low dimensionality. 3) Achieve convergence depends on using initial guesses of high optical intensity that can ionize the system that we are attempting to control. The issues listed above makes traditional procedures for QOC unsuitable in order to attempt controlling the dynamics of molecular systems. This thesis is aimed to design a pseudo-spectral approach to the QOC, in which the optimization of the pulse is performed using a genetic algorithm (GA) and is constrained to employ linear combination of analytic sub-pulses having the advantages of: 1) The methodology produces pulse shapes that are stressed to have experimental realm and at the same time avoid damaging the molecule along the optimization process 2) The pulse shapes have to be optimized only once per molecule and/or molecular process offering the opportunity of collecting a data-base of optimal pulses for broad set of molecules (or molecular processes) systematically 3) It is possible to employ the information collected along the GA optimization in order to infer the control mechanism induced by the pulse. As a consequnce of the set of improvements listed formerly, the methodology proposed in this thesis is a promising progress towards formulations of QOC suitable for the study and analysis of the QOC of molecular quantum dynamics determined onthe-fly.

Semiclassical study of the optimal control of molecular rotors in tilted fields

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