Strong field dynamics with ultrashort electron wave packet replicas

TL;DR

This paper presents a theoretical study of electron dynamics driven by combined VUV attosecond pulse trains and infrared lasers, revealing phase-dependent modulations in electron absorption linked to wave packet replicas.

Contribution

The authors develop a minimal analytical model to describe electron energy distribution and photon absorption as functions of phase delay, advancing understanding of ultrashort electron wave packet dynamics.

Findings

Absorption probability modulates strongly with phase delay at certain photon energies.

Higher photon energies show no phase delay dependence, matching experimental results.

The model explains electron dynamics using wave packet replicas created by attosecond pulses.

Abstract

We investigate theoretically electron dynamics under a VUV attosecond pulse train which has a controlled phase delay with respect to an additional strong infrared laser field. Using the strong field approximation and the fact that the attosecond pulse is short compared to the excited electron dynamics, we arrive at a minimal analytical model for the kinetic energy distribution of the electron as well as the photon absorption probability as a function of the phase delay between the fields. We analyze the dynamics in terms of electron wave packet replicas created by the attosecond pulses. The absorption probability shows strong modulations as a function of the phase delay for VUV photons of energy comparable to the binding energy of the electron, while for higher photon energies the absorption probability does not depend on the delay, in line with the experimental observations for helium and argon, respectively.