Anomalous Evolution of Moiré Trion Quantum Coherence under Charge Filling in a Semiconducting Twisted WSe₂/MoSe₂ Heterobilayer.

Abstract

Quantum confinement from the periodic moiré potential leads to the formation of a quantum two-level system featuring long coherence time in the WSe₂/MoSe₂ heterobilayer. Controllable charge filling has recently emerged as a significant technique for tuning the electronic properties of moiré excitonic systems. However, the interplay between the coherence of moiré-based excited states and charge-filling remains to be explored. In this study, we investigated the evolution of moiré charged exciton (trion) quantum coherence in WSe₂/MoSe₂ heterobilayer devices as a function of charge filling. With the occupation of moiré sites by doped electrons defined by the filling factor, a blueshift in moiré trion emission accompanied by a line width narrowing of approximately 400 μeV is clearly observed. We used an advanced experiment of light emission interferogram to distinguish the contribution from inhomogeneous and homogeneous broadening. Owing to the suppression of trion scattering, an extension of trion quantum coherence reaching beyond 25 ps near a filling factor of 1 is demonstrated, which indicates the signature of strongly correlated electronic states of moiré trion. This study establishes the quantum coherence of the moiré excitonic states as an effective microscopic probe for exploring the moiré excitonic systems of two-dimensional semiconducting heterobilayers.