Coherent Control Experiments on Molecular Multiphoton Excitation

Jean‐Claude Diels

Jing Su, Shaohao Chen, Agnieszka Jaroń-Becker +1 more

Bijoy K Dey

We give a framework for molecular multiphoton excitation processes induced by an optimally designed electric field. The molecule is initially prepared in a coherent superposition state of two of its eigenfunctions. The relative phase of the two superposed eigenfunctions has been shown to control the optimally designed electric field which triggers multiphoton excitation in the molecule. This brings forth flexibility in designing the optimal field in the laboratory by suitably tuning the molecular phase and hence by choosing the most favourable interfering routes that the system follows to reach the target. We follow the quantum fluid dynamical formulation for designing the electric field for the HBr molecule.

Bijoy K Dey

We give a framework for molecular multiphoton excitation processes induced by an optimally designed electric field. The molecule is initially prepared in a coherent superposition state of two of its eigenfunctions. The relative phase of the two superposed eigenfunctions has been shown to control the optimally designed electric field which triggers multiphoton excitation in the molecule. This brings forth flexibility in designing the optimal field in the laboratory by suitably tuning the molecular phase and hence by choosing the most favourable interfering routes that the system follows to reach the target. We follow the quantum fluid dynamical formulation for designing the electric field for the HBr molecule. 1.

W. R. Garrett, Yifei Zhu, L. Deng +1 more

Liat Levin, Daniel M. Reich, Moran Geva +3 more

Quantum coherent control of ultrafast bond making and the subsequent molecular dynamics is crucial for the realization of a new photochemistry, where a shaped laser field is actively driving the chemical system in a coherent way from the thermal initial state of the reactants to the final state of the desired products. We demonstrate here coherent control over the relative yields of Mg2 molecules that are generated via photoassociation and subsequently photodriven into different groups of final states. The strong-field process involves non-resonant multiphoton femtosecond photoassociation of a pair of thermally hot magnesium atoms into a bound Mg2 molecule and subsequent molecular dynamics on electronically excited states. The branching-ratio control is achieved with linearly chirped laser pulses, utilizing the different chirp dependence that various groups of final molecular states display for their post-pulse population. Our joint experimental and theoretical study establishes the feasibility of high degree coherent control over quantum molecular dynamics that is initiated by femtosecond photoassociation of thermal atoms.