Berlin 2024 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 36: Poster III

HL 36.18: Poster

Mittwoch, 20. März 2024, 18:00–20:30, Poster E

Pump-probe spectroscopy of Rydberg excitons in TMDC monolayers — •Max Wegerhoff, Moritz Scharfstädt, Andrea Bergschneider, and Stefan Linden — Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany

Quantum photonic technologies rely on strong optical nonlinearities, such as those provided by Rydberg atoms. The solid-state analog to this are Rydberg excitons. Rydberg excitons in cuprous oxides with principal quantum numbers of up to n=25 show strong optical nonlinearities, whose signatures could be detected by pump-probe spectroscopy [1]. In TMDC monolayers, which exhibit particularly strongly bound excitons, an increased nonlinearity could already be established for exciton-polaritons with n=2 [2].

Here, we report on the pump-probe spectroscopy of Rydberg states of excitons in TMDC monolayers at liquid helium temperatures. We use spectrally broad femtosecond probe pulses and a spectrometer to measure the transient differential reflectivity spectra. The degenerate pump-pulses are suppressed in a cross-polarized configuration such that the same Rydberg state is excited and probed. The doping of the monolayers is defined by electrical gating and kept neutral for the measurements.

[1] Heckötter, J., Walther, V., Scheel, S. et al., Nat Commun 12, 3556 (2021)

[2] Gu, J., Walther, V., Waldecker, L. et al., Nat Commun 12, 2269 (2021)

Keywords: TMDC monolayers; Rydberg excitons; Pump-probe spectroscopy