Ultrafast Rabi oscillation of a Gaussian atom ensemble

Abstract

We investigate Rabi oscillation of an atom ensemble in Gaussian spatial distribution. By using the ultrafast laser interaction with the cold atomic rubidium vapor spatially confined in a magneto-optical trap, the oscillatory behavior of the atom excitation is probed as a function of the laser pulse power. Theoretical model calculation predicts that the oscillation peaks of the ensemble-atom Rabi flopping fall on the simple Rabi oscillation curve of a single atom and the experimental result shows good agreement with the prediction. We also test the the three-pulse composite interaction $R_x(\pi/2)R_y(\pi)R_x(\pi/2)$ to develop a robust method to achieve a higher fidelity population inversion of the atom ensemble.