Selective Vibrational Population Transfer using Combined STIRAP and Counter-Diabatic Fields

TL;DR

This study demonstrates that combining STIRAP with counter-diabatic fields enhances vibrational population transfer efficiency in polyatomic molecules, especially within complex state manifolds, surpassing traditional methods under certain conditions.

Contribution

It introduces a combined STIRAP and counter-diabatic field approach for improved vibrational energy transfer in complex molecular systems, with analysis of its effectiveness and stability.

Findings

Combined approach outperforms ordinary STIRAP in efficiency.

Approximate CDF is effective for multi-state systems.

Method remains stable under CDF variation.

Abstract

We report studies of state-to-state vibrational energy transfer in an isolated polyatomic molecule driven by combined stimulated Raman adiabatic passage (STIRAP) and counter-diabatic fields (CDF), using as vehicles selective population of one of a pair of near degenerate states in SCCl$_2$ and enhancing the yield of HNC in the HCN/HNC isomerization reaction. The efficiency of the population transfer within a subset of states embedded in a dense manifold of states is examined for the cases that the transition dipole moments between the initial and target states are much smaller than and comparable to the transition dipole moments between background states, and for the case that the subset states have large transition dipole moments with the background states. We show that, in a subset of states that is coupled to background states, a combination of STIRAP fields and CDFs that do not individually generate processes that are competitive with the desired population transfer can generate greater population transfer efficiency than can ordinary STIRAP with field strength and/or pulse duration similarly restricted. We also show that the exact CDF for an isolated three level system is a useful approximation to the exact CDF for three and five state systems embedded in background states, and we report a study of the stability of the STIRAP + approximate CDF control protocol to variation of the CDF.