Coherent control phase lag across doubly-excited atomic strontium resonances in an $\omega-2\omega$ interference scheme

TL;DR

This paper extends the calculation of phase lag in coherent control from atomic barium to strontium, analyzing its spectrum and electron correlation effects near specific ionization thresholds.

Contribution

It provides the first predictions of phase lag for strontium's doubly excited states, considering electron correlations and Coulomb interactions.

Findings

Phase lag behavior is complex and cannot be fully explained by time delay analysis.

Electron correlations significantly influence the phase lag in strontium.

The study offers insights into the spectrum and decay channels of doubly excited strontium states.

Abstract

Accurate calculations of phase lag associated with coherent control where an excited system decays into more than one product channel have recently been reported for atomic barium in PhysRevA.105.013113 (2022). The present study extends the calculations to make predictions of that observable for another alkaline earth atom, strontium, with a discussion of its spectrum and phase lag for energies between the $Sr^{+}$ $4d_{3/2}$ and $4d_{5/2}$ thresholds. We will explore the physics influenced by the electron correlations of strontium and the long-range Coulomb potential. The behavior of the phase lag cannot be simply addressed by a time delay analysis, although the latter is often used to address the prominent channel of resonance decay of doubly excited states.