Rabi oscillations of Morris-Shore-transformed N-state systems by elliptically polarized ultrafast laser pulses

Abstract

We present an experimental investigation of ultrafast laser-driven Rabi oscillations of atomic rubidium. Because the broadband spectrum of an ultrafast laser pulse simultaneously couples all of the electronic hyperfine transitions between the excited and ground states, the complex excitation linkages involved with the D-1 or D-2 transition are energy degenerate. By application of the Morris-Shore transformation, this study shows that the considered multistate system is reduced to a set of independent two-state systems and dark states. In experiments performed by ultrafast laser interactions of atomic rubidium in the strong interaction regime, we demonstrate that the ultrafast dynamics of the considered system are governed by no more than two decoupled Rabi oscillations when it interacts with ultrafast laser pulses of any polarization state. We further show the implications of this result with regard to possible control of photoelectron polarizations.