Attosecond time-resolved photoelectron holography

Abstract

Ultrafast strong-field physics provides insight into quantum phenomena that evolve on an attosecond time scale, the most fundamental of which is quantum tunneling. The tunneling process initiates a range of strong field phenomena such as high harmonic generation (HHG), laser-induced electron diffraction, double ionization and photoelectron holography—all evolving during a fraction of the optical cycle. Here we apply attosecond photoelectron holography as a method to resolve the temporal properties of the tunneling process. Adding a weak second harmonic (SH) field to a strong fundamental laser field enables us to reconstruct the ionization times of photoelectrons that play a role in the formation of a photoelectron hologram with attosecond precision. We decouple the contributions of the two arms of the hologram and resolve the subtle differences in their ionization times, separated by only a few tens of attoseconds.

R -matrix-with-time-dependence theory for ultrafast atomic processes in arbitrary light fields

“…The generalized RMT approach, introduced in this article, represents a viable theoretical tool for investigating this transition, in a systematic fashion, as the driving wavelength (or number of photons required for ionization) increases. However, we emphasize that the newly developed suite of codes appear promising for a plethora of other novel applications, whether in regard of fundamental, laser-induced atomic processes (in particular, inner-shell dynamics [99] and the production of valence ring currents [93]), or experimental schemes of contemporary interest (including the attoclock [20,[31][32][33][34][35], HHG in cross-polarized [15,75] and circularly or elliptically polarized [9][10][11][12] laser pulses, as well as attosecond photoelectron holography [100]). As a result, the methodology presented here constitutes a significant and timely development in R-matrix techniques, facilitating the accurate simulation, and more profound understanding, of ultrafast, many-body dynamics in atomic systems exposed to arbitrarily polarized light fields.…”

Two-color phase-of-the-phase spectroscopy with circularly polarized laser pulses

“…(the correction of order ξ to the saddle point solution does not contribute in first order to the action). The term proportional to cos θ in (17) changes sign (i.e., the phase jumps by π) when the square bracket vanishes,…”

Deep Learning for Feynman’s Path Integral in Strong-Field Time-Dependent Dynamics

“…As a result, despite of the notable success of these methods, there still exist a large number of unexplored regimes, including the open question about whether one could truly achieve the quantumclassical correspondence. Actually, with increasingly so-phisticated experiments, the limitation of existing semiclassical methods based on FPI for reproducing and explaining some quantum phenomena has been becoming increasingly evident due to the limited amount of paths, especially for the new attosecond measurements where a series of high-resolution photoelectron spectra with different pump-probe delays are needed to obtain attosecond time-resolved movies of electrons [25][26][27][28][29][30][31][32].Since the game Go was mastered by deep neural networks (DNNs), deep learning (DL) has received extensive attention [33,34]. Recently, this technique has powered many fields of science, including planning chemical syntheses [35], acceleration of super-resolution localization microscopy and nudged elastic band calculations [36][37][38][39], classifying scientific data [40,41], solving highdimensional problems in condensed matter systems [42][43][44][45][46][47][48], reconstructing the shape of ultrashort pulses [49], and so on.…”

“…As a result, despite of the notable success of these methods, there still exist a large number of unexplored regimes, including the open question about whether one could truly achieve the quantumclassical correspondence. Actually, with increasingly so-phisticated experiments, the limitation of existing semiclassical methods based on FPI for reproducing and explaining some quantum phenomena has been becoming increasingly evident due to the limited amount of paths, especially for the new attosecond measurements where a series of high-resolution photoelectron spectra with different pump-probe delays are needed to obtain attosecond time-resolved movies of electrons [25][26][27][28][29][30][31][32].…”