The time-scale of nonlinear events driven by strong fields: can one control the spin coupling before ionization runs over?

Abstract

An initially populated spin state of an ion chain interacting with an external field can decay via spin coupling or via ionization. Using a simple two-level Hamiltonian we investigate the relation between spin-coupling and ionization rate and identify conditions for an efficient spin-control via a non-resonant Stark effect by suppressing ionization. The results are confirmed in solving the time-dependent Schrödinger equation for the interaction of a laser field with a spin-coupled model system where two electrons and a nucleus move in a collinear configuration. It is thus shown, that quantum control of intersystem crossing can indeed be effective if the intensity of the external field and the accompanying Stark-shift is adjusted properly to the spin-coupling strength.

High-fidelity quantum control via Autler-Townes splitting

“…Refs. [14][15][16][17][18][19][20][21]. The perturbed singlet-triplet states, arising from the level mixing due to the spin-orbit coupling, represent a gateway to gain access to the otherwise dark triplet states in these systems.…”

Molecular events in the light of strong fields: A light‐induced potential scenario

“…[100][101][102] However, under usual circumstances very strong fields are needed, such that the rate of ionization at the required laser intensity is faster than the rate of inter-system conversion. [103,104] certain conditions, the schemes can only operate when the spin-orbit coupling is weak, reverting to a few-level problem. [104,105] Other intramolecular or non-adiabatic couplings can be controlled in a similar manner.…”

“…[103,104] certain conditions, the schemes can only operate when the spin-orbit coupling is weak, reverting to a few-level problem. [104,105] Other intramolecular or non-adiabatic couplings can be controlled in a similar manner. For instance, one can generate LIACs that prevent the initial nuclear wave packet to reach a certain conical intersection in order to avoid energy deactivation.…”

Lighting the Landscape: Molecular Events Under Dynamic Stark Shifts

“…For instance, in the control of the spin state of the molecule, we have shown how electric pulses or electromagnetic fields can be used to avoid a singlet-triplet transition, by suitably modifying the singlet and triplet LIPs such that there is no crossing between them [101][102][103]. However, under usual circumstances very strong fields are needed, such that the rate of ionization at the required laser intensity is faster than the rate of inter-system conversion [104,105]. Under certain conditions, the schemes can only operate when the spin-orbit coupling is weak, reverting to a few-level problem [105,106].…”

“…However, under usual circumstances very strong fields are needed, such that the rate of ionization at the required laser intensity is faster than the rate of inter-system conversion [104,105]. Under certain conditions, the schemes can only operate when the spin-orbit coupling is weak, reverting to a few-level problem [105,106].…”