Ultrafast photoelectron holography with tailored fields

Laser-induced holographic patterns that form in above-threshold ionization (ATI) photoelectron angular distributions (PADs) are a powerful tool for investigating ultrafast electron dynamics in real time (Huismans et al, Science 331, 61 (2011)). Indeed, there is experimental evidence of coupling between nuclear and electronic motion in PH (Meckel et al, Nat. Phys. 10, 594 (2014), Walt et al, Nat. Comm. 15, 651 (2017)). These patterns require a reference and probe signal, which are associated with different types of interfering electron orbits. Most theoretical models of photoelectron holography (PH), however, either treat the contributing orbits classically, or neglect the binding potential in the continuum, which is an oversimplification. Using a novel approach developed at UCL in Professor Carla Faria's group, the Coulomb Quantum Orbit Strong Field Approximation (CQSFA) (Lai et al, Phys. Rev. A 92, 043407 (2015)), we have achieved a much better understanding of how the key holographic patterns form, and of the interplay between the Coulomb potential and external field (Maxwell et al, Phys. Rev. A 96, 023420 (2017)). Our studies have also uncovered a myriad of holographic patterns that are normally overlooked in the literature. In an experimental setting, these patterns are however obfuscated by more prominent features.

In this project, the student will seek particular pulse shapes, frequencies and polarizations, in order to enhance or suppress specific holographic patterns. Milestones include extending the CQSFA to fields of arbitrary shapes, temporal profiles and polarization, exploring field symmetries, and studying how interference patterns are affected by the interaction with the environment and multielectron effects. These studies are essential for tackling extended systems in future work.