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arXiv · 2510.14695

Quantum beats of exciton-polarons in CsPbI3 perovskite nanocrystals

A. V. Trifonov·M. O. Nestoklon·M. -A. Hollberg·S. Grisard·D. Kudlacik·E. V. Kolobkova·M. S. Kuznetsova·S. V. Goupalov·J. M. Kaspari·D. E. Reiter·D. R. Yakovlev·M. Bayer·I. A. Akimov
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Abstract

Exciton-phonon interactions govern the energy level spectrum and thus the optical response in semiconductors. In this respect, lead-halide perovskite nanocrystals represent a unique system, for which the interaction with optical phonons is particularly strong, giving rise to a ladder of multiple exciton states which can be optically excited with femtosecond pulses. We establish a new regime of coherent exciton-polaron dynamics with exceptionally long coherence times (T2 ~300 ps) in an ensemble of CsPbI3 nanocrystals embedded in a glass matrix. Using transient two-pulse photon echo at 2 K temperature, we observe quantum beats between the exciton-polaron states. Within a four-level model, we directly quantify the exciton-phonon coupling strength through the Huang-Rhys factors of 0.05-0.1 and 0.02-0.04 for low-energy optical phonons with energies of 3.2 and 5.1 meV, respectively. The pronounced size dependence of both coupling strengths and phonon lifetimes offers a path to tune the optical transitions between polaron states and to tailor the coherent optical dynamics in perovskite semiconductors for solid-state quantum technologies.

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A. V. Trifonov, M. O. Nestoklon, M. -A. Hollberg, S. Grisard, D. Kudlacik, E. V. Kolobkova, M. S. Kuznetsova, S. V. Goupalov, J. M. Kaspari, D. E. Reiter, D. R. Yakovlev, M. Bayer, I. A. Akimov. 2025-10-16. Quantum beats of exciton-polarons in CsPbI3 perovskite nanocrystals. https://doi.org/10.1038/s41467-026-73506-1

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