Tunable quantum coherence in transition metal dichalcogenide bilayers*

Quantum coherence associated with excitons and valleys in transition metal dichalcogenide (TMD) monolayers is lost on an ultrafast time scale (~ 200 fs), imposing limits on how such pseudospins can be manipulated. Here, we investigate how quantum coherence of excitons are modified in hBN encapsulated TMD bilayers. By applying two-dimensional coherent spectroscopic techniques, we separate different dephasing pathways and explore methods for controlling such decoherence.