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International Conference Physics and Control

Quantum control of dissociation of an iodine molecule by one and two femtosecond laser pulses excitation

Mikhail S. Ananyevskiy, A. S. Vetchinkin, Oleg M. Sarkisov, Stanislav Ya Umanskii, Аlexander L. Fradkov, Yu. A. Zotov

Published Oct 4, 2006• 3 citations

Abstract

We introduce two approaches to the synthesis of the optimized schemes of dissociation control of diatomic molecules. The first one bases on the early introduced speed-gradient algorithms of the quantum control. We use the semi classical model of molecular dynamics onto the ground state. The introduced algorithm is a robust and it has only one tuning parameter. The numerical results of the control of the predissociation of iodine molecule illustrate the high possibility of the dissociation for 100 fs laser pulse. The second approach bases on quantum model of dissociation through B excited electronic state. This model doesn't assume the solving of any time-depended equations. The optimized scheme of iodine dissociation with different nuclear isotopes is obtained. The best isotope separation achieves up to 300 fs with 80% efficiency.

DOI: 10.1109/phycon.2005.1514061

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We theoretically study the control of two-photon excitation to bound and dissociative states in a molecule induced by trains of laser pulses, which are equivalent to certain sets of spectral phase modulated pulses. To this end, we solve the time-dependent Schr\"odinger equation for the interaction of molecular model systems with an external intense laser field. Our numerical results for the temporal evolution of the population in the excited states show that, in the case of an excited dissociative state, control schemes, previously validated for the atomic case, fail due to the coupling of electronic and nuclear motion. In contrast, for excitation to bound states the two-photon excitation probability is controlled via the time delay and the carrier-envelope phase difference between two consecutive pulses in the train.

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The predissociation of a diatomic molecule after excitation by an ultrashort laser pulse leads to a succession of partial nuclear wave packets on the dissociative potential curve. Matter wave interferences result from their evolution. We show here theoretically how control pulses inducing Rabi oscillations on the electronic atomic part of the wave function can change totally the shape of the nuclear interference pattern. This is a consequence of the entanglement between the electronic and nuclear parts of the wave function. Application to information storage is finally discussed.

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