Observing angular precession of a Rydberg wave packet due to spin-orbit coupling by orthogonal polarized half-cycle pulses

We investigate the response of an $np$ Rydberg wave packet to orthogonal polarized half-cycle pulses(HCPs) over the course of its field free evolution. The population redistribution from $p$ to $s$ states is highly sensitive to the polarization of HCPs and changes with the precession of the electron orbits due to spin-orbit coupling. The selection rules of HCP redistribution are obtained and an intuitive classical interpretation is given.