Optimal three-state field-free molecular orientation with terahertz pulses

We present a combined analytical and numerical investigation to show how an optimal control field can be designed to generate maximum field-free orientation of molecules for three populated rotational states. Based on a model involving pure rotational ladder-climbing excitation between rotational st...

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Bibliographic Details
Published in:arXiv.org 2021-05
Main Authors: Qian-Qian, Hong, Li-Bao, Fan, Chuan-Cun Shu, Henriksen, Niels E
Format: Article
Language:English
Subjects:
Amplitudes
Optimal control
Orientation
Rotational states
Terahertz frequencies
Online Access:Get full text
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Summary:We present a combined analytical and numerical investigation to show how an optimal control field can be designed to generate maximum field-free orientation of molecules for three populated rotational states. Based on a model involving pure rotational ladder-climbing excitation between rotational states, a set of optimal amplitude and phase conditions are analytically derived for the applied control fields. The maximum degree of orientation can be achieved when the field satisfies amplitude and phase conditions at the two transition frequencies. Multiple optimal solutions exist and to examine these conditions, we devise a quantum coherent control scheme using two terahertz pulses and successfully apply it to the linear polar molecule HCN at ultracold temperature. The sensitivity of both populations and phases of rotational states to control field parameters, i.e., the detuning, bandwidth, and time delay, is analyzed for understanding the optimal orientation mechanism. This work thus examines the frequency domain landscape belonging to optimal pulses.
ISSN:2331-8422
DOI:10.48550/arxiv.2105.13690