Highly energy-tunable quantum light from moiré-trapped excitons.

H Baek,K Watanabe,M Brotons-Gisbert,Z X Koong,M Rambach,T Taniguchi,A Campbell,B D Gerardot

doi:10.1126/sciadv.aba8526

H Baek, K Watanabe + Show 6 more

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https://doi.org/10.1126/sciadv.aba8526

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Abstract

Photon antibunching, a hallmark of quantum light, has been observed in the correlations of light from isolated atomic and atomic-like solid-state systems. Two-dimensional semiconductor heterostructures offer a unique method to create a quantum light source: Moiré trapping potentials for excitons are predicted to create arrays of quantum emitters. While signatures of moiré-trapped excitons have been observed, their quantum nature has yet to be confirmed. Here, we report photon antibunching from single moiré-trapped interlayer excitons in a heterobilayer. Via magneto-optical spectroscopy, we demonstrate that the discrete anharmonic spectra arise from bound band-edge electron-hole pairs trapped in moiré potentials. Last, we exploit the large permanent dipole of interlayer excitons to achieve large direct current (DC) Stark tuning up to 40 meV. Our results confirm the quantum nature of moiré-confined excitons and open opportunities to investigate their inhomogeneity and interactions between the emitters or energetically tune single emitters into resonance with cavity modes.

Highlights

The ability to stack unlimited combinations of atomic layers with arbitrary crystal angle ( ) has opened an innovative paradigm in quantum material design
Tunable Bloch minibands emergent in moiré lateral superlattices have enabled remarkable observations with graphene heterostructures, such as nearly flat bands with narrow bandwidths at specific [1] that can lead to superconductivity [2] and correlated insulator states [3]
Our heterobilayer samples consist of ML MoSe2 and ML WSe2 encapsulated by hexagonal boron nitride

Summary

Introduction

The ability to stack unlimited combinations of atomic layers with arbitrary crystal angle ( ) has opened an innovative paradigm in quantum material design. Stacking any two different ML TMDs creates a heterobilayer with type II band alignment [6], which exhibits spatially indirect interlayer excitons (IXs) with highly tunable photoluminescence (PL) energy [7,8,9,10]. Similar to graphene bilayers (BLs), the constituent TMD MLs interact with each other and create moiré potentials dependent on , which can hybridize wave functions across both layers [14,15,16] or lead to uniform high-density arrays of quantum emitters [17, 18] or topological bands whose properties can be manipulated by electric or strain fields [19,20,21]

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