Van der Waals-Zeeman Colloquium

Tuesday, 13 May 2007, 16:00h

Multiple scattering of light in cold atoms : coherent wave transport and lasing

Prof. Robin Kaiser
Institut Nonlineaire de Nice, Nice

Coherent backscattering is signature of interferences in multiple scattering which can be observed with samples far from the Anderson localization threshold. We observed resonant coherent backscattering of light from a sample of laser-cooled atoms. Multiple scattering of light is known to exist in such samples since it limits the atomic density achievable in magneto-optical traps. Direct manifestations of multiple scattering of light in cold atoms such as ''radiation trapping'' had already been observed, but our experiments allowed to probe the interference effects in this situation. Adding gain in such systems allows for lasing with cold as gain medium, opening the way towards a random laser with cold atoms. Other intriguing features of multiple scattering of light are their mechanical effects, which can be described by a Coulomb type long range interaction. We will discuss several consequences of these mechanical effects, including collective self-sustained oscillations