Quantum coherent control of the photoelectron angular distribution in bichromatic-field ionization of atomic neon

Abstract

We investigate the coherent control of the photoelectron angular distribution in bichromatic atomic ionization. Neon is selected as target since it is one of the most popular systems in current gas-phase experiments with free-electron lasers (FELSs). In particular, we tackle practical questions, such as the role of the fine-structure splitting, the pulse length, and the intensity. Time-dependent and stationary perturbation theory are employed, and we also solve the time-dependent Schrödinger equation in a single-active electron model. We consider neon ionized by a FEL pulse whose fundamental frequency is in resonance with either 2p − 3s or 2p − 4s excitation. The contribution of the nonresonant two-photon process and its potential constructive or destructive role for quantum coherent control is investigated.

New Method for Measuring Angle-Resolved Phases in Photoemission

“…More details can be found in Ref. [56]. Further derivations within the independent particle approximation are given in the Appendix.…”

Coherent control schemes for the photoionization of neon and helium in the Extreme Ultraviolet spectral region

“…In lowest (non-vanishing) order perturbation theory, the angle-integrated probability W 0 does not depend on the relative phase ϕ between the two harmonics for even κ . The odd β s, however, vary with ϕ , thereby revealing interference between the two ionisation pathways 12 , 13 , 30 – 32 . In contrast, the angle-integrated probability varies with ϕ for odd κ , while the ϕ -dependence of the anisotropy parameters is generally weak.…”

“…Our first example is the coherent control of the ionisation of neon by the fundamental and its second harmonic radiation. The experimental scheme was recently reported 3 , and a detailed description of the theoretical approaches, comparison with conventional perturbation theory and the role of triplet terms in the continuum can be found in 32 .…”

“…Here we have built on the results of 32 , and considered a different range of parameters in order to optimise the experimental conditions. While that study indicated that a quantitative comparison with published data may be possible, here we reach a different conclusion.…”

“…Recent theoretical work on XUV coherent control of H 30 and Ne 31 , 32 has explored a number of parameters of the experiments, with a view to interpreting the experimental data. The most recent work 32 discussed in extensive detail the formal derivation of equations describing the observable asymmetry. Here we use these results as a starting point for new calculations, and take a different point of view: we seek to understand to what extent effects are observable under optimal conditions.…”