Observation of Suppression of Light Scattering Induced by Dipole-Dipole Interactions in a Cold-Atom Ensemble

5 pages, 5 figuresInternational audienceWe study the emergence of collective scattering in the presence of dipole-dipole interactions when weilluminate a cold cloud of rubidium atoms with a near-resonant and weak intensity laser. The size of theatomic sample is comparable to the wavelength of light. When we gradually increase the number of atomsfrom 1 to ∼450, we observe a broadening of the line, a small redshift and, consistently with these, a strongsuppression of the scattered light with respect to the noninteracting atom case. We compare our data tonumerical simulations of the optical response, which include the internal level structure of the atoms