Moir\'e exciton dynamics and moir\'e exciton-phonon interaction in a WSe$_2$/MoSe$_2$ heterobilayer

TL;DR

This study investigates the dynamics and phonon interactions of moiré excitons in a twisted WSe₂/MoSe₂ heterobilayer, revealing phonon-resonant excitation and potential for quantum applications.

Contribution

It provides new insights into moiré exciton-phonon interactions and exciton dynamics in twisted heterobilayers using near-resonant photoluminescence excitation spectroscopy.

Findings

Selective excitation of moiré exciton ground state at phonon resonance

Observation of discrete energy levels in exciton ensembles

Suppressed phonon interaction enabling exploration of quantum phenomena

Abstract

Moir\'e patterns with angular mismatch in van der Waals heterostructures composed of atomically thin semiconducting materials are a fascinating platform to engineer the optically generated excitonic properties towards novel quantum phenomena. The moir\'e pattern as a periodic trap potential can give rise to spatially ordered zero-dimensional (0D) exciton ensembles, which offers the possibility for dense coherent quantum emitters and quantum simulation of many-body physics. The intriguing moir\'e exciton properties are affected by their dynamics and exciton-phonon interaction. However, the moir\'e exciton dynamics and the interaction between the moir\'e exciton and phonon are still elusive. Here, we report the moir\'e exciton and phonon interaction in a twisted WSe$_2$/MoSe$_2$ heterobilayer based on near-resonant photoluminescence excitation spectroscopy. We observed the selective excitation of the ground state of the moir\'e exciton at phonon resonance. The otherwise negligible small absorption below the continuum state is a hallmark of the density of states of a 0D-like system. In addition, the excitation power dependence of the PL spectra reveals the dynamics of moir\'e exciton ensembles between different potential minima with discrete energy levels via the resonant phonon scattering process. The results presented here of the moir\'e exciton dynamics under suppressed phonon interaction could pave a new way for the exploration of novel quantum phenomena of the moir\'e exciton towards potential applications in quantum optics.