München 2004 – scientific programme

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Q: Quantenoptik und Photonik

Q 47: Quanteneffekte IV

Q 47.4: Talk

Friday, March 26, 2004, 11:45–12:00, HS 218

Coherent backscattering of light by atoms in the saturated regime — •Thomas Wellens^1,2, Benoit Gremaud², Dominique Delande², and Christian Miniatura¹ — ¹Laboratoire Ondes et Désordre, FRE 2302 du CNRS, 1361 route des Lucioles, F-06560 Valbonne — ²Laboratoire Kastler Brossel, Université Pierre et Marie Curie, 4 Place Jussieu, F-75005 Paris

We present the first calculation of coherent backscattering of light by saturated atoms. We consider two distant atoms in free space, interacting with a quasi-monochromatic laser pulse. By restricting ourselves to two-photon scattering processes, we employ a perturbative approach, valid up to second order in the incident laser intensity. The backscattering enhancement factor, i.e. the intensity detected in exact backscattering direction divided by the background intensity, is found to be smaller than two (after excluding single scattering). This indicates a loss of coherence between the doubly scattered light emitted by atom 1 and 2, respectively. Since the undetected photon carries information about the path of the detected photon, the coherence loss can be explained by a which-path argument, in analogy to a double-slit experiment.