Journal Article

Collective atomic scattering and motional effects in a dense coherent medium

Bothwell, T., Schachenmayer, J., Nicholson, T. L., Rey, A. M., Bishof, M., Kaiser, R., Ye, J., Zhu, B., Lukin, M. D., Bromley, S. L., Yelin, S. F., Zhang, X.

2016

Overview

We investigate collective emission from coherently driven ultracold 88 Sr atoms. We perform two sets of experiments using a strong and weak transition that are insensitive and sensitive, respectively, to atomic motion at 1 μK. We observe highly directional forward emission with a peak intensity that is enhanced, for the strong transition, by > 10 3 compared with that in the transverse direction. This is accompanied by substantial broadening of spectral lines. For the weak transition, the forward enhancement is substantially reduced due to motion. Meanwhile, a density-dependent frequency shift of the weak transition (∼10% of the natural linewidth) is observed. In contrast, this shift is suppressed to < 1% of the natural linewidth for the strong transition. Along the transverse direction, we observe strong polarization dependences of the fluorescence intensity and line broadening for both transitions. The measurements are reproduced with a theoretical model treating the atoms as coherent, interacting radiating dipoles. Light scattering from a dense coherent medium is determined by the interplay of dispersive and radiative dipole–dipole interactions. Here, the authors control the motional effects that obscure the coherence of scattered light and study collective emission in a driven gas of cold strontium-88 atoms.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 140/125 / 639/624/400/1100 / 639/766/36 / Emissions / Humanities and Social Sciences / multidisciplinary / Physics / Quantum Physics / Science / Science (multidisciplinary)