Moiré excitons: From programmable quantum emitter arrays to spin-orbit–coupled artificial lattices

TLDR

Highly uniform nanodot arrays in van der Waals heterostructures provide an ordered nanoscale landscape that is essential for high‑performance quantum optoelectronics and for creating artificial lattices of interacting quasiparticles. The gauge structure imprinted on exciton wavefunctions by the moiré pattern enables spin–orbit coupling when nanodots hop into superlattices. Moiré effects produce long‑lived interlayer excitons that can be tuned electrically or by strain from perfect quantum‑emitter arrays to excitonic superlattices with giant spin‑orbit coupling, invert spin‑optical selection rules, and host complex‑hopping honeycomb superlattices featuring Dirac and Weyl nodes linked by spin‑momentum‑locked topological edge modes.

Abstract

Highly uniform and ordered nanodot arrays are crucial for high performance quantum optoelectronics including new semiconductor lasers and single photon emitters, and for synthesizing artificial lattices of interacting quasiparticles towards quantum information processing and simulation of many-body physics. Van der Waals heterostructures of 2D semiconductors are naturally endowed with an ordered nanoscale landscape, i.e. the moir\'e pattern that laterally modulates electronic and topographic structures. Here we find these moir\'e effects realize superstructures of nanodot confinements for long-lived interlayer excitons, which can be either electrically or strain tuned from perfect arrays of quantum emitters to excitonic superlattices with giant spin-orbit coupling (SOC). Besides the wide range tuning of emission wavelength, the electric field can also invert the spin optical selection rule of the emitter arrays. This unprecedented control arises from the gauge structure imprinted on exciton wavefunctions by the moir\'e, which underlies the SOC when hopping couples nanodots into superlattices. We show that the moir\'e hosts complex-hopping honeycomb superlattices, where exciton bands feature a Dirac node and two Weyl nodes, connected by spin-momentum locked topological edge modes.