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Wolfgang Langbein

Publications and source records attributed to Wolfgang Langbein.

4 recordsLinked to original sources
PubMed2006

Heterodyne spectral interferometry for multidimensional nonlinear spectroscopy of individual quantum systems.

A novel implementation of transient nonlinear spectroscopy is presented that allows the study of the transient nonlinear polarization emitted from individual electronic transitions. Both the amplitude and the phase of the polarization are retrieved, permitting the implementation of multidimensional spectroscopy in the excitation pulse delays. The technique is shown to detect mutual coherent coupling in a group of individual, localized excitonic transitions.

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PubMed2005

Microscopic measurement of photon echo formation in groups of individual excitonic transitions.

The third-order polarization emitted from groups of individual localized excitonic transitions after pulsed optical excitation is measured. We observe the evolution of the nonlinear response from the case of a free polarization decay for a single transition, to that of a photon echo for many transitions. The echo is shown to arise from the mutual rephasing of the emission from individual transitions.

Journal Article↗
PubMed2002

Elastic scattering dynamics of cavity polaritons: evidence for time-energy uncertainty and polariton localization.

The directional dynamics of the resonant Rayleigh scattering from a semiconductor microcavity is investigated. When optically exciting the lower polariton branch, the strong dispersion results in a directional emission on a ring. The coherent emission ring shows a reduction of its angular width for increasing time after excitation, giving direct evidence for the time-energy uncertainty in the dynamics of the scattering by disorder. The ring width converges with time to a finite value, a direct measure of an intrinsic momentum broadening of the polariton states localized by multiple disorder scattering.

Journal Article↗