Abstract

Atomically thin crystals of transition metal dichalcogenides (TMDCs) have emerged as a new platform to study tightly bound excitons and many-body excitations in ultimately thin materials. Their giant dipole coupling to light makes them prime materials for (nano-)photonic and electronic devices, and for fundamental research on cavity quantum electrodynamics. Additionally, TMDC excitons can emit at room temperature and they offer unique, tailorable interactions based on van-der-Waals engineering.

The strong coupling between excitons and confined photons yields the formation of exciton-polaritons; these are solid-state quasiparticles with properties linked to matter (Coulomb interactions, magnetic response) and light (extended spatial and temporal coherence). The bosonic character of exciton-polaritons enables their capability to condense into a macroscopic coherent state [1], similar to the laser emission, with additional features such as controllable nonlinear interactions.

In this talk, I will firstly discuss our recent results on the condensation of TMDC exciton-polaritons at cryogenic temperatures [2], created in a sample embedding a monolayer of MoSe2 in a hybrid optical microcavity composed by AlGaAs mirrors and a dielectric top mirror. Secondly, in a different sample composed by a monolayer of WSe2 embedded in a fully dielectric mirror, I will show recent results on condensation signatures of room-temperature TMDC exciton-polaritons (extended first order coherence) [3].

Our future experiments will explore open-cavity configurations containing optical lattices (see recent related work [4]) coupled to TMDC interlayer excitons [5]. We believe that this platform offers a powerful approach to study complex systems, such as the Bose-Hubbard model.

[1] J. Kasprzak, et al. Nature 443, 409 (2006).

[2] C. Anton-Solanas, et al. Nature Materials 20, 1233 (2021).

[3] H. Shan, et al. Nature Communications 12, 6406 (2021).

[4] L. Lackner, Nat Commun 12, 4933 (2021).

[5] Michl, arXiv:2105.09948 [cond-mat] (2021).

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