Scientists have for the first time visualized excitons confined in moiré superlattices of twisted bilayer MoS2, a two-dimensional material. This breakthrough allows for a better understanding of how twisting between layers of a 2D material creates a periodic potential that traps these quasiparticles, opening new avenues for the design of optoelectronic and quantum devices.

Twisted bilayer MoS2 forms a "moiré" superlattice when one layer is slightly rotated with respect to the other. This periodic structure generates an electronic potential that can confine excitons, which are bound electron-hole pairs. Until now, direct observation of this confinement at the nanoscale had been a challenge. The team used an advanced near-field optical microscopy technique to map the spatial distribution of excitons with unprecedented resolution.

The results show that excitons are preferentially localized in regions of the moiré superlattice where the confinement potential is deepest. This localization is crucial for controlling the material's optical and electronic properties, allowing, for example, for light emission at specific points or the creation of isolated quantum states. The ability to visualize and manipulate these confined excitons is a fundamental step towards engineering materials with tailored properties for applications in quantum computing, high-sensitivity sensors, and new quantum light sources.