Biomedical subjects

O Sigwarth

Publications and source records attributed to O Sigwarth.

3 recordsLinked to original sources

PubMed2005

Localization of matter waves in two-dimensional disordered optical potentials.

We consider ultracold atoms in 2D disordered optical potentials and calculate microscopic quantities characterizing matter wave quantum transport in the noninteracting regime. We derive the diffusion constant as a function of all relevant microscopic parameters and show that coherent multiple scattering induces significant weak localization effects. In particular, we find that even the strong localization regime is accessible with current experimental techniques and calculate the corresponding localization length.

Journal Article↗

PubMed2004

Magnetic field enhanced coherence length in cold atomic gases.

We study the effect of an external magnetic field on coherent backscattering of light from a cold rubidium vapor. We observe that the backscattering enhancement factor can be increased with B. This surprising behavior shows that the coherence length of the system can be increased by adding a magnetic field, in sharp contrast with usual situations. This is mainly due to the lifting of the degeneracy between Zeeman sublevels. We find good agreement between our experimental data and a full Monte Carlo simulation, taking into account the magneto-optical effects and the geometry of the atomic cloud.

Journal Article↗

PubMed2002

Hanle effect in coherent backscattering.

We study the shape of the coherent-backscattering (CBS) cone obtained when resonant light illuminates a thick cloud of laser-cooled rubidium atoms in the presence of a homogenous magnetic field. We observe new magnetic field-dependent anisotropies in the CBS signal. We show that the observed behavior is due to the modification of the atomic-radiation pattern by the magnetic field (Hanle effect in the excited state).

Journal Article↗