Attosecond Quantum-Beat Spectroscopy in Helium

TL;DR

This paper demonstrates attosecond spectroscopy to observe and analyze the real-time evolution of electron wavepackets in helium, revealing detailed ionization dynamics through quantum beat signals.

Contribution

It introduces a method combining XUV attosecond pulses and IR pulses to measure and control electron wavepacket dynamics in helium with high temporal resolution.

Findings

Observation of quantum beat signals in photoelectron spectrograms

Real-time tracking of electron wavepacket evolution

Determination of time-dependent ionization dynamics of 2p state

Abstract

The evolution of electron wavepackets determines the course of many physical and chemical phenomena and attosecond spectroscopy aims to measure and control such dynamics in real-time. Here, we investigate radial electron wavepacket motion in Helium by using an XUV attosecond pulse train to prepare a coherent superposition of excited states and a delayed femtosecond IR pulse to ionize them. Quantum beat signals observed in the high resolution photoelectron spectrogram allow us to follow the field-free evolution of the bound electron wavepacket and determine the time-dependent ionization dynamics of the low-lying 2p state.