Quantum Trajectory Selection via Strong Field Simulator

Strong field ionization and recollision is often described using a semi-classical model, whereby the electron first tunnels out of the atomic potential, then it is accelerated in the strong field, and finally it recollides with its parent ion. This 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. We demonstrate the strong field simulator (SFS) method, which simulates strong field recollision by replacing the tunneling ionization step with single photon ionization from a sub-cycle extreme-ultraviolet (XUV) pulse with photon energies at or above the ionization threshold. By varying the delay between the strong field and the XUV pulse, the SFS will allow for unprecedented studies of individual classes of trajectories, as well as accessing new ones. These measurements could reveal quantum aspects absent in the classical description, along with observing novel light-matter interactions. Here, we will describe a new apparatus that will enable these studies, and discuss some initial results.