Interferometric Scheme for Resolving the Dynamics of an Attosecond Wave packet

We propose an interferometric technique aimed at resolving the dynamics of a photoelectron wave packet emitted from two distinct residual photo-ion channels in the ionization of an atom by an ultra-short UV pulse. Our method employs a non-overlapping delayed few-cycle optical pulse, with its frequency tuned precisely at the transition energy between the bound states of the photo-ion. Through simplified two-channel time-dependent numerical simulations, complemented by an analytical treatment based on time-dependent perturbation theory, we illustrate that the resulting interferences, observed either in the ionization or asymptotic momentum, provide access to the energy-resolved relative phase of the ionization amplitudes between the two channels without measurement-induced effects. Furthermore, we investigate the potential of this technique to temporally resolve the wave packet evolution on the two distinct potential energy surfaces by manipulating the delay between the pump and probe pulses.