Highorder harmonic radiation of a single helium atom

High-order harmonic radiation of a single helium atom driven by a strong laser pulse Attila Czirják and Szilárd Majorosi University of Szeged, Hungary ELI-ALPS, Szeged, Hungary

Outline • Motivation • Quantum simulation • COMSOL model • Results • Summary

Motivation Krausz and Ivanov: Attosecond physics, Reviews of Modern Physics, 81, 2009.

Klasszikus és kvantum dinamika összehasonlítása Motivation Cavalieri et. al. Nature 2007 5

Klasszikus és kvantum dinamika összehasonlítása Motivation Cavalieri et. al. Nature 2007 6

Quantum simulation • Solve TDSE for He atom, driven by a short laser pulse Majorosi and Czirják, Comput. Phys. Commun. 208, 9 (2016).

Quantum simulation • Solve TDSE for He atom, driven by a short laser pulse – Single active electron – MCTDHF

Quantum simulation • Solve TDSE for He atom, driven by a short laser pulse • Compute high-harmonic spectra

Quantum simulation • Solve TDSE for He atom, driven by a short laser pulse • Compute high-harmonic spectra • Compute time dependent current density

COMSOL model • COMSOL Multiphysics and RF Module • axial symmetric formulation of the electromagnetic wave equation in the frequency domain. • Imported data for external current density • PML at the outgoing boundary

COMSOL model

Results h 8 h 9

Results h 20 h 21

Results h 40 h 41

Summary • Atomic electron drive by a strong laser field: very weak effect, high accuracy needed, quantum simulation with specialized code, • Resulting current density imported into COMSOL, • A simple COMSOL model can compute the electric field in the frequency domain, • We expect that our results contribute to the deeper understanding of the HHG emission process.

Acknowledgments The project has been supported by the European Union, co-financed by • the European Social Fund, – Grant No. EFOP-3. 6. 2 -16 -2017 -00005 (University of Szeged) • by the European Regional Development Fund, – GINOP-2. 3. 2 -15 -2016 -00036 (University of Szeged) – GINOP-2. 3. 6 -15 -2015 -00001 (Extreme Light Infrastructure – Attosecond Light Pulse Source) Thank you for your attention!