The question of how long it takes a particle to tunnel through a potential barrier has been a
subject of intense theoretical debate for the last 80 years. In this decade of attosecond …

Due to their very nature, ultrafast phenomena are often accompanied by the occurrence of
nonadiabatic effects. From a theoretical perspective, the treatment of nonadiabatic …

Over the last decade, control of atomic-scale electronic motion by non-perturbative optical
fields has broken tremendous new ground with the advent of phase-controlled high-energy …

The balance of the linear photon momentum in multiphoton ionization is studied
experimentally. In the experiment argon and neon atoms are singly ionized by circularly …

We investigate experimentally the validity of proposed theories extending the tunneling
approximation towards the multiphoton regime in strong-field ionization of helium. We …

Attosecond physics offers new insights into ultrafast quantum phenomena involving electron
dynamics on the fastest measurable timescales. The rapid progress in this field enables us …

Interferometry has been at the heart of wave optics since its early stages, resolving the
coherence of the light field and enabling the complete reconstruction of the optical …

We present an ellipticity-resolved study of momentum distributions arising from strong-field
ionization of helium. The influence of the ion potential on the departing electron is …

The tunnelling model of ionization applies only to longitudinal fields: quasistatic electric
fields that do not propagate. Laser fields are transverse: plane wave fields that possess the …

We present experimental data on the nonadiabatic strong field ionization of atomic hydrogen
using elliptically polarized femtosecond laser pulses at a central wavelength of 390 nm. Our …