Abstract

The spatial distribution of cesium atoms in a 1D optical molasses are probed by measuring the absorption (or amplification) of a weak laser beam. Very narrow stimulated Raman and Rayleigh resonances are observed. The position of the Raman resonance gives access to the oscillation frequency of the atoms in the wavelength-scale optical potential. From the width of the Raman lines (~35 kHz), we deduce the damping time of this oscillation, which exhibits a dramatic lengthening due to the spatial confinement of atoms to a fraction of optical wavelength (Lamb–Dicke effect). Furthermore, the narrow stimulated Rayleigh signals (8 kHz) give experimental evidence for a large scale spatial order of the atomic gas presenting some analogy with an antiferromagnetic medium.

© 1992 Optical Society of America