Discussion of the adiabatic hypothesis in control schemes using exceptional points

TL;DR

This paper investigates the feasibility of using laser pulses to induce vibrational transfers via exceptional points in molecules, revealing significant non-adiabatic effects and the impact of dissipation on adiabatic control schemes.

Contribution

It provides a direct numerical analysis showing the limitations of adiabatic control near exceptional points in dissipative molecular systems.

Findings

Adiabatic flips are difficult to achieve due to non-adiabatic exchanges.

Dissipation significantly affects the control process.

Longer pulse durations are required for successful control, especially in Na2.

Abstract

We present calculations for the action of laser pulses on vibrational transfer within the H2+ and Na2 molecules in the presence of dissipation due to photodissociation of the molecule. The laser fields perform closed loops surrounding exceptional points in the laser parameter plane of intensity and wavelength. In principle the process should produce controlled vibrational transfers due to an adiabatic flip of the dressed eigenstates. We directly solve the Schr\"odinger equation with the complete time-dependent field instead of using the adiabatic Floquet formalism which initially suggested the design of the laser pulses. Results given by wavepacket propagations disagree with predictions obtained using the adiabatic hypothesis. Thus we show that there are large non-adiabatic exchanges and that the dissipative character of the dynamics renders the adiabatic flip very difficult to obtain. Using much longer durations than expected from previous studies, the adiabatic flip is only obtained for the Na2 molecule and with strong dissociation.