International Workshop on ATOMIC PHYSICS

November 24 - 27, 2014

Scientific coordinators:

Scientific report

MPI für Kernphysik, Heidelberg

Main focus of the workshop
The meeting brought together international leaders and experts in the field of strong-field light-matter interaction, in particular concerning atoms, molecules and clusters/nanoparticles in intense or high-energy light/laser fields.  The main focus theme was "Slow electrons and short light pulses".  The interest in this topic was born several years ago, where the so-called low-energy structure in strong-field (tunneling-/multiphoton-) photoemission spectra was found to be the result of the interaction of an electron with the spatially extended potential of its parent ion.  Since then, a number of further benchmark results, and low-energy "fine structure" have been obtained by continuous progress in experiments (enhanced resolution of detectors, improved control over laser fields and better statistics) as well as in theory (improved quasi-classical models and analysis).  Slow electrons occur also in a range of other scenarios (e.g. harder photons, clusters, Rydberg atoms) outside the special topic of low-energy (fine) structure.  The main goal of this workshop was to create and convey a comprehensive picture of the various physics processes that lead to slow-electron creation, and to disentangle and/or unify these mechanisms.

Key topics and corresponding speakers
To approach the main focus topic under a variety of perspectives—to obtain new insight and to create impact for other fields—speakers covering a broad variety of related fields in their talks were invited to the workshop:

- Quantum Control: Esa Räsänen, Matthias Wollenhaupt, Stefanie Gräfe

- Molecules: Eberhard Gross, Jamal Berakdar, Hans Jakob Wörner, Itzik Ben-Itzhak, Francoise Remacle,

- Clusters, Nanoparticles, Solids: Thomas Fennel, Frank Stienkemeier, Thomas Möller, Matthias Kling, Thomas Brabec, Bernd Schütte

- Quantum Statistics: Andreas Buchleitner, Peter Lambropoulos, Hossein Sadeghpour

- Strong x-rays/FEL: Markus Drescher, Robin Santra, Georg Schmid, Agapi Emmanouilidou

- Rydberg systems, trapped atoms and ions: Georg Raithel, Alejandro Saenz, Robert Jones

- Few-body systems: Anthony Starace, Nirit Dudovich, Reinhard Dörner, Boris Bergues, Dieter Bauer, Ursula Keller, Enderalp Yakaboylu, Olga Smirnova, Cosmin Blaga, Ulf Saalmann, Christian Ott, Zenghu Chang, Chii-Dong Lin, Manfred Lein, Koudai Toyota, Jens Biegert, Lutz Fechner

 General scientific outcome and perspectives
While being counterintuitive at first—strong fields typically create fast electrons by strong acceleration forces—the observation and analysis of slow electrons allows to focus on and to understand the challenging physics beyond the strong-field approximation, where atomic potential and laser field govern the strong-field dynamics on equal footing.

Participants of the Workshop that study apparently different processes shared their most recent results.  Throughout the presentations, several connections and interfaces opened up showing that similar experimental observations and theoretical concepts are present across areas. In particular, slow electrons occur in free and bound states (e.g. Rydberg atoms), can be created and controlled with laser frequencies ranging from the THz to the x-ray domain, emerge by quantum and classical processes in few-body as well as in complex systems.

This experience widened the scope for all participants, allowing them to think about their problems in a broader sense and approaching them with new tools and ideas. Cooperations among participants were fostered and forged. Very importantly, younger researchers were able to make contacts to experts, helped by stimulating discussions at their excellently prepared posters.