Optimized pulses for population transfer via laser induced continuum structures

TL;DR

This paper applies optimal control to design pulse shapes that maximize population transfer between bound states via a continuum, outperforming Gaussian STIRAP pulses especially under certain detuning and loss conditions.

Contribution

It introduces optimal pulse shaping with bang-interior controls for continuum-mediated population transfer, demonstrating improved efficiency over traditional Gaussian pulses.

Findings

Optimal controls exhibit bang-interior and interior-bang forms.

Optimal pulses outperform Gaussian STIRAP in various detuning and loss scenarios.

Transfer efficiency increases with the Fano factor magnitude.

Abstract

We use optimal control in order to find the optimal shapes of pulses maximizing the population transfer between two bound states which are coupled via a continuum of states. We find that the optimal bounded controls acquire the bang-interior and interior-bang form, with the bang part corresponding to the maximum allowed control value and the interior part to values between zero and the maximum. Then, we use numerical optimal control to obtain the switching times and the interior control values. We compare our results with those obtained using Gaussian STIRAP pulses, and find that the optimal method performs better, with the extent of improvement depending on the effective two-photon detuning and the size of incoherent losses. When we consider effective two-photon resonance, the improvement is more dramatic for larger incoherent losses, while when we take into account the effective two-photon detuning, the improvement is better for smaller incoherent losses. We also obtain how the transfer efficiency increases with increasing absolute value of the Fano factor. The present work is expected to find application in areas where the population transfer between two bound states through a continuum structure plays an important role, for example coherence effects, like population trapping and electromagnetically induced transparency, optical analogs for light waves propagating in waveguide-based photonic structures, and qubits coupled via a continuum of bosonic or waveguide modes.