Dresden 2011 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 6: Quantum Effects: Light Scattering and Propagation

Q 6.1: Talk

Monday, March 14, 2011, 10:30–11:00, SCH A01

Multiple scattering of photons on disordered atomic samples: localization vs. nonlinearity — •Ralf Blattmann, Felix Eckert, Jochen Zimmermann, Vyacheslav Shatokhin, Thomas Wellens, and Andreas Buchleitner — Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3 , 79104 Freiburg

When single photons are multiply scattered inside a disordered cloud of cold atoms, interference between different scattering paths manifests themselves in weak and strong localization effects such as coherent backscattering and – in the most extreme case – even a complete suppression of classical diffusion. At higher laser intensities, however, nonlinear and inelastic multi-photon scattering events must be taken into account, and compete with the coherent transport effects mentioned above. First, we show – by means of diagrammatic scattering theory – that the coherent backscattering peak is reduced, or even inverted, for classical light propagating in a nonlinear disordered medium, and generalize these results to the regime of strong localization. In addition to the nonlinearity, we then address inelastic scattering resulting from the interaction of atoms with the quantized radiation field. In particular, we will analyze scattering of intense laser light by two atoms with degenerate energy levels. Finally, we consider coherent propagation of one and two photons in a one-dimensional disordered chain of two-level atoms, where – in contrast to 3D – recurrent scattering cannot be neglected.