13.3.26

Article: Exciton coherence propagation measured with non-local four-wave mixing micro-spectroscopy

 

Excitons—electron–hole pairs bound by Coulomb interaction in a semiconductor—can act as carriers of optical coherence over mesoscopic distances. Using femtosecond laser excitation and coherent nonlinear micro-spectroscopy, the spatio-temporal propagation of exciton wave packets in a high-quality CdTe quantum well can be directly tracked on length scales reaching 10 µm.

Excitons created within the optical light cone inherit the phase of the excitation pulse and can transport this phase information while diffusing through the quantum well before recombining radiatively. Time-of-flight measurements allow simultaneous observation of both exciton density and coherence during propagation.

The results highlight the potential of excitons to mediate coherent links within semiconductor nanostructures, opening new possibilities for compact excitonic circuits. Such approaches may provide an alternative route toward miniaturized architectures for future quantum technologies and contribute to studies of coherent carrier transport relevant for fields ranging from quantum information to photovoltaics and biological energy transfer.

Authors: M. Raczyński, A. Dydniański, K. E. Połczyńska, G. Szwed, A. Szczerba, J.-W. Jung, G. Nogues, W. Langbein, P. Kossacki, W. Pacuski, and J. Kasprzak

Optica Vol. 13, Issue 2, pp. 362-365 (2026) 

https://doi.org/10.1364/OPTICA.582443