Resolving Optimal Electron-Hole Dynamics in IR-assisted XUV Photoionization for Quantum Control of High-Order Harmonic Generation*

In photoionization, the correlated dynamics of low-lying orbital electrons is affected by the interaction between the parent ion and the ejected photoelectron. For slow photoelectrons, interchannel couplings affect the degree of coherence between hole states [1]. Recent works have suggested that such couplings may be the missing link to understanding the dynamics of high order harmonic generation before the photoionized electron recombines with the parent atom [2]. It has also been shown that details of the electron-hole dynamics are imprinted in the HHG yield and can be probed using a combination of XUV and IR fields [3]. In this work, we theoretically investigate IR-assisted XUV-photoionization schemes for quantum control of harmonic generation under the influence of the hole dynamics in the photoion. The XUV field configuration promotes the photoelectron wave packet to the same continuum state following different photoionization pathways prior to recombination. We analyze and time-resolve the details of electron-density dynamics yielding to the optimized HHG spectrum using an interferometric scheme that involves two atomic targets generating HHG radiation that interfere in the same detection plane as a function of the time delay between the fields acting on each target. We show a direct mapping between the optimized electron-density dynamics and interfering HHG radiation phase spectrum.

[1] S. Pabst et al., Phys. Rev. Lett. 106, 053003 (2010)

[2] Y. Mairesse et al., Phys. Rev. Lett. 104, 213601 (2010)

[3] Leeuwenburgh et al., Phys. Rev. Lett. 111, 123002 (2013)