Optical Measurement of Multielectron During Recollision

The study of photoionization time delays is one of the major achievements of attosecond science. These measurements are typically performed using photoelectron spectrometers with isolated attosecond pulses or pulse trains. As the inverse process of photoionization, photorecombination is known to exhibit similar time delays, which can arise from multielectron interaction and electronic structure. Here, we demonstrate that, by perturbing the recollision process with a co-phased weak field, photorecombination delay due to multielectron interaction can be measured entirely optically by observing the modulation of the emitted extreme ultraviolet (XUV) radiation with respect to the delay between the driving and perturbing fields. We first investigate this by simulating recollision in the one-dimensional helium atom and study recollision-induced Fano resonance excitation. We then extend this work to more realistic systems and investigate recollision and the giant resonance in xenon using time-dependent density functional theory. Our results agree with experimental results measured in similar experimental conditions, showing the effect of the giant dipole resonance in xenon has on the recolliding electron. This work opens a new path to the study of strong-field induced ultrafast electron correlation by employing an all-optical measurement method.