Control by decoherence: Weak field control of an excited state objective

Gil Katz*, Mark A. Ratner, Ronnie Kosloff

*Corresponding author for this work

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

Coherent control employing a broadband excitation is applied to a branching reaction in the excited state. In a weak field for an isolated molecule, a control objective is only frequency dependent. This means that phase control of the pulse cannot improve the objective beyond the best frequency selection. Once the molecule is put into a dissipative environment a new timescale emerges. In this study, we demonstrate that the dissipation allows us to achieve coherent control of branching ratios in the excited state. The model studied contains a nuclear coordinate and three electronic states: the ground and two coupled diabatic excited states. The influence of the environment is modeled by the stochastic surrogate Hamiltonian. The excitation is generated by a Gaussian pulse where the phase control introduced a chirp to the pulse. For sufficient relaxation, we find significant control in the weak field depending on the chirp rate. The observed control is rationalized by a timing argument caused by a focused wavepacket. The initial non-adiabatic crossing is enhanced by the chirp. This is followed by energy relaxation which stabilizes the state by having an energy lower than the crossing point.

Original languageEnglish (US)
Article number015003
JournalNew Journal of Physics
Volume12
DOIs
StatePublished - Jan 19 2010

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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