Diagrammatic approach to attosecond delays in photoionization

TL;DR

This paper introduces a diagrammatic, many-body perturbation theory approach to accurately calculate attosecond photoionization delays, improving understanding and measurement techniques in attosecond metrology.

Contribution

It provides an ab initio, general method to compute photoionization delays, including atomic response corrections, applicable to complex many-electron systems.

Findings

Correction curves for attosecond pulse characterization schemes are presented.

Photoelectron delays in many-electron atoms can be measured with proper continuum--continuum delay subtraction.

The method is extendable to more complex systems with systematic correlation effects.

Abstract

We study laser-assisted photoionization by attosecond pulses using a time-independent formalism based on diagrammatic many-body perturbation theory. Our aim is to provide an ab inito route to the "delays" for this above-threshold ionization process, which is essential for a quantitative understanding of attosecond metrology. We present correction curves for characterization schemes of attosecond pulses, such as "streaking", that account for the delayed atomic response in ionization from neon and argon. We also verify that photoelectron delays from many-electron atoms can be measured using similar schemes if, instead, the so-called continuum--continuum delay is subtracted. Our method is general and it can be extended also to more complex systems and additional correlation effects can be introduced systematically.