Nonlinear coupling between two Zeeman coherence gratings stored in cold atoms

Abstract

We investigate the storage and the nonlinear coupling of two Zeeman coherence gratings in an ensemble of cold cesium atoms. This nonlinear coupling was revealed through the analysis of the total energy that can be extracted from the atomic medium as a function of the relative intensities of the grating writing beams, which presented a minimum when their intensities were made equal. A theoretical model using the density matrix formalism accounts quantitatively well for the observed results and allowed us to identify several channels in which energy can be delivered in the reading process.