Ultrafast quantum beats of anisotropic excitons in atomically thin ReS2

Sangwan Sim, Doeon Lee, Artur V. Trifonov, Taeyoung Kim, Soonyoung Cha, Ji Ho Sung, Sungjun Cho, Wooyoung Shim, Moon Ho Jo, Hyunyong Choi

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16 Citations (Scopus)


Quantum beats, periodic oscillations arising from coherent superposition states, have enabled exploration of novel coherent phenomena. Originating from strong Coulomb interactions and reduced dielectric screening, two-dimensional transition metal dichalcogenides exhibit strongly bound excitons either in a single structure or hetero-counterpart; however, quantum coherence between excitons is barely known to date. Here we observe exciton quantum beats in atomically thin ReS2 and further modulate the intensity of the quantum beats signal. Surprisingly, linearly polarized excitons behave like a coherently coupled three-level system exhibiting quantum beats, even though they exhibit anisotropic exciton orientations and optical selection rules. Theoretical studies are also provided to clarify that the observed quantum beats originate from pure quantum coherence, not from classical interference. Furthermore, we modulate on/off quantum beats only by laser polarization. This work provides an ideal laboratory toward polarization-controlled exciton quantum beats in two-dimensional materials.

Original languageEnglish
Article number351
JournalNature communications
Issue number1
Publication statusPublished - 2018 Dec 1

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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    Sim, S., Lee, D., Trifonov, A. V., Kim, T., Cha, S., Sung, J. H., Cho, S., Shim, W., Jo, M. H., & Choi, H. (2018). Ultrafast quantum beats of anisotropic excitons in atomically thin ReS2 Nature communications, 9(1), [351]. https://doi.org/10.1038/s41467-017-02802-8