Probing In-Situ Twistable Moiré Quantum Emitters with Near-Field Scanning Optical Microscopy

Transition metal dichalcogenide (TMD) Moiré superlattices are formed when two layers of TMD materials are stacked with a slight twist angle. This creates a periodic potential that can trap electrons and holes to form an array of optically active single emitters and other exotic quantum states. Compared to other solid-state emitters, Moiré emitters exist in a planar crystal and do not rely on crystal defects, giving the advantage of scalability, electrical tunability, optimized photon extraction efficiency, and ease of integration with nano-photonic structures to realize single-photon nonlinear optical effects. The twist angle in TMD Moiré superlattices critically determines the properties of the superlattice potential and thereby the optical properties of the emitters. But twisted devices are generally fabricated with a fixed angle that cannot be modified once the device has been made. In addition, the Moiré unit cell is very small, making it difficult to address single emitters with free-space optics. In this work, we propose and develop a new platform for reliable creation and read-out of Moiré emitters. This platform combines two capabilities: 1) a “Twistronics” apparatus that can bring two vdW layers into direct contact and rotate them relative to each other which allows for precise in-situ control of the twist angle between the layers, and 2) a near-field scanning optical probe that can focus and collect light from a subwavelength scale spot, making it possible to address single photon emitters in moiré superlattices. We discuss the merits and challenges of the design and report our progress in using it to study the optical properties of TMD heterobilayers. We believe that our proposed platform will be a powerful tool for exploring the correlated physics of moiré superlattices and for developing new quantum technologies based on these materials.