Localisation faible de la lumière dans un gaz d´atomes froids

Recent experimental results show that the interference contrast observed in coherent backscattering (CBS) of light by cold atoms is drastically reduced with respect to classical disordered media. In the present theoretical contribution, we study the impact of the degeneracy of the atomic dipole transition on weak localisation of light. The non-scalar components of the atomic scattering operator are characteristic of the internal structure, and strongly modify the interference properties of multiple light scattering. A systematic analysis in terms of irreducible tensors permits to calculate exact analytical expressions for the single and double scattering contributions to the CBS signal for arbitrarily degenerate atomic dipole transitions. Furthermore, we sum up the series of ladder and crossed diagrams that describe the average scattered light intensity and the weak localisation corrections, respectively. We find that the degeneracy of the atomic transition has negligeable impact on the average light amplitude, small impact on the average intensity, but decisive impact on the interference corrections. The internal degrees of freedom very effectively reduce the interference leading to weak localisation and, therefore, the CBS signal for any degenerate atomic dipole transition.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Ludwig-Maximilians-Universität

Year

2001

Author dc:creator

• Müller, Cord Axel

Repository record source_url

https://edoc.ub.uni-muenchen.de/400/

OAI identifier oai:identifier

oai:edoc.ub.uni-muenchen.de:400