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Cascaded emission of single photons from the biexciton in monolayered WSe2



Yu-Ming He, Oliver Iff, Nils Lundt, Vasilij Baumann, Marcelo I. Davanco, Kartik Srinivasan, Sven Hofling, Christian Schneider


Monolayers of transition metal dichalcogenide materials emerged as a new material class to study excitonic effects in solid state. They benefit from the enormous coulomb correlations between electrons and holes, as a result of reduced dielectric screening. Especially in WSe2, sharp emission features have been observed at cryogenic temperatures, which were acting as single photon sources. It has been commonly assumed that this is a result of a tight exciton localization, which induces an anharmonic excitation spectrum via Pauli blocking. However, the clear cut evidence of the hypothesis, namely the demonstration of a localized biexciton with a binding energy exceeding the linewidth of the exciton, is elusive. Here, we unambiguously demonstrate the existence of a localized biexciton in a monolayer of WSe2, which triggers an emission cascade of single photons. The biexciton is identified by its superlinearity and distinct polarization in continuous wave micro-photoluminescence experiments. We evidence the cascaded nature of the emission process in a cross-correlation experiment, which yields a strong bunching behavior. Our work will pave the way to a new generation of quantum optics experiments with two-dimensional semiconductors.
Nature Photonics


Transition metal dichalcogenides, Single-photon sources


He, Y. , Iff, O. , Lundt, N. , Baumann, V. , Davanco, M. , Srinivasan, K. , Hofling, S. and Schneider, C. (2016), Cascaded emission of single photons from the biexciton in monolayered WSe2, Nature Photonics, [online],, (Accessed July 14, 2024)


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Created November 9, 2016, Updated October 12, 2021