Exciton-polaritons in two-dimensional transition metal dichalcogenides | Chitraleema Chakraborty

Two-dimensional transition metal dichalcogenides (TMDC) hosts strongly bound excitons owing to strong Coulomb interaction. In addition to neutral excitons, unintentional doping in the exfoliated monolayer also results in the formation of trions, the bound state of an electron and exciton. We show strong coupling between exciton and cavity photon by integrating monolayer TMDC as an active material within a planar microcavity structure. We observe an anomalous trion dispersion with negative curvature near zero in-plane momentum. Our theoretical analysis suggests the presence of electron mediated interaction between the exciton-polariton and the trion-polariton in the microcavity. 2D TMDCs can be associated with an additional quantum degree of freedom known as valleys which can be optically accessed via polarization state of excited photons. In this talk, I will also discuss how we have used valley exciton-polaritons to circumvent intervalley dephasing and preserve finite valley coherence at room temperature. Our work suggests a pathway for studying interesting regimes in quantum many-body physics yielding possible new phases of quantum matter and room temperature valley-polaritonic devices.