Maximal refraction and superluminal propagation in a gaseous nanolayer

Abstract

We present an experimental measurement of the refractive index of high density Rb vapor in a gaseous atomic nanolayer. We use heterodyne interferometry to measure the relative phase shift between two copropagating laser beams as a function of the laser detuning and infer a peak index n = 1.26 \pm 0.02, close to the theoretical maximum of 1.31. The large index has a concomitant large index gradient creating a region with steep anomalous dispersion where a sub-nanosecond optical pulse is advanced by >100 ps over a propagation distance of 390 nm, corresponding to a group index of -1x10^5, the largest negative group index measured to date.

References in corpus (5)

• Experimental demonstration of quantum memory for light
• Cooperative atom-light interaction in a blockaded Rydberg ensemble
• Absolute absorption on the rubidium D lines: comparison between theory and experiment
• Wide-bandwidth, tunable, multiple-pulse-width optical delays using slow light in cesium vapor
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