Within the first twp reporting periods, the PI and his Team have concluded a variety of breakthrough results in the field light-matter coupling with atomically thin materials. The Team could show, that it is possible to reach the strong coupling Regime of exciton and Photons in a microcavity with a single embedded monolayer (N. Lundt et al. 10.1038/ncomms13328) and they demonstrated the valley selective strong coupling at cryogenic, (N. Lundt et al. 2D Materials 10.1088/2053-1583/aa6ef2) as well as at room temperature (N. Lundt et al. Physical Review B 10.1103/physrevb.96.241403). The Team furthermore demonstrated the formation of so-called hybrid polaritons composed of III-V and TMDC excitons (M. Wurdack et al. Nature Communications 10.1038/s41467-017-00155-w) and subsequently the bosonic condensation of exciton-polaritons in a hybrid cavity at cryogenic temperature (M. Waldherr et al. Nature Communications 10.1038/s41467-018-05532-7).
The ERC Team identified techniques to Isolate single excitons in WSe2 monolayers via strain engineering (O. Iff et al. Optics Express 10.1364/oe.26.025944) and subsequently, the coupling of a strain-localized single exciton (single photon sources) to a plasmonic resonance (L. Tripathi et al. ACS Photonics 10.1021/acsphotonics.7b01053). Further, the team demonstrated the formation of biexciton states via quantum corelations (He et al. Nature Communications 10.1038/ncomms13409 28).
Among the major achievements in the third reporting period, the novel Valley Hall Effect of Exciton Polaritons (Lundt et al. Nature Nanotechnology 14 770 (2019)) , the initial demonstration of Valley Zeeman Splitting of TMD polaritons (Klaas et al. PRB 100 121303 (2019)) and full control over the effect of valley coherence in real- and artificial magnetic fields (Rupprecht et al. 2D Materials 7 035025 (2020)) were reported. We have furthermore reported giant strain-tuneability of TMD-based single photon sources (Iff et al. Nanoletters 19 6931 (2019)).
During the fourth reporting period we have demonstrated the first condensation of exciton-polaritons using TMDC monolayer in Nature Materials at cryogenic temperatures (Anton-Solanas et al. Nature Materials 20 1233 (2021)) as well as the coherence of exciton-polaritons at room temperature (M2.3) (Shan et al. Nature Communications 12, 6406 (2021)) . We furthermore observed the the surprising phenomena of polariton induced triplet quenching (or exciton brightening), (Shan et al. Nature Communications 13 3001 (2022)) . Finally, our technological developments of tunable open cavities have allowed us to demonstrate fully tunable polaritons in photonic lattices at room temperature (Lackner et al. Nature Communications 12, 4933 (2021)). We have furthermore reported the successful realization of TMDC-based single photon sources using the strain-positioning technique in combination with lateral Bragg-grating cavities (Iff et al. Nanoletters 21 4715 (2021)) (corresponding Milestones M3.2.2 and M3.3).
The following major scientific achievements were accomplished in the final reporting period (PR5), and successfully published and disseminated in peer review articles:
Following our demonstration of spatial coherence of exciton-polaritons, both at cryogenic conditions as well as at room temperature in the fourth reporting period , we were able to proof quantum coherence in a polariton system in the fifth period. The effect was demonstrated via the Hanbury-Brown and Twiss experiment, which allowed us to reconstruct the second order correlation function of the emitted light from our polariton fluid. The paper was published in Physical Review Letters in 2023. (Shan et al. Physical review Letters 131, 206901 (2023))
We have furthermore reported the successful realization of TMDC-based single photon sources in our open, tunable microcavity. The paper marks the state-of-the-art in the field, demonstrating high brightness, high purity quantum emission, and finally quantum coherence of single photons emitted by WSe2 quantum dot. T (Drawer, Mitryakhin, Shan et al. Nanoletters 23, 8683 (2023)). The soruce performance was directly exploited in the first quantum communication demonstration utilizing transition metal dichalcogenides, in collaboration with the group of T. Heindel at TU Berlin (Gao et al. NJP 2D Materials and their applications (2023))
