The Strong Field Simulator: An Attosecond Study of Electron Recollision

We report on a novel attosecond study of electron recollision using sub-cycle XUV pulses to ionize noble gases dressed by an infrared field of sufficient intensity to drive recollision, this technique is dubbed the Strong Field Simulator. Previous strong-field experiments have been limited as tunneling can happen at times within the infrared field cycle that are weighted by the instantaneous ionization probability proportional to field strength. Thus, the measurement is confined to trajectories near the extreme of the electric field. In this experiment, the XUV pulses serve to replace the tunneling step of the semi-classical model, while the infrared field still accelerates the electron and drives recollision. Isolating the ionization step from the other two, we select the moment of ionization, and correspondingly the electron's quantum trajectory, by varying the arrival time of the XUV pulse with respect to the infrared field. We observe the outcomes of these singular trajectories by measuring the electron energy spectra in addition to the relative rateThis three-step model assumes that electrons follow distinct classical trajectories in the second step that correspond to specific ionization times in the first. Past work on understanding this phenomenon has been limited, as the measured observables correspond to a superposition of all possible trajectories of single and double ionization. The XUV/infrared delay, infrared and XUV wavelengths, infrared intensity, and target species are all controllable parameters allowing for a robust multi-dimensional study of electron recollision.