A team of researchers from UC Berkeley and other institutions observed moiré excitons in nearly aligned WSe₂/WS₂ heterostructures. Moiré excitons are novel excited states that emerge in two-dimensional materials due to the periodic potential created by the moiré superlattice formed when two atomically thin layers are twisted at a specific angle. The study reports the first experimental observation of these excitons in WSe₂/WS₂ heterostructures, where the moiré potential is much stronger than the exciton kinetic energy, leading to multiple flat exciton minibands. These excitons exhibit distinct gate-dependent behaviors, different from those in WSe₂ monolayers or large-twist-angle heterostructures. The findings suggest that moiré superlattices can be used to explore and control exotic excited states, such as topological excitons and a correlated exciton Hubbard model, in transition metal dichalcogenides. The research highlights the potential of moiré superlattices to engineer novel quantum phenomena in 2D heterostructures, offering a platform for studying strongly correlated electron systems. The study was published in Nature and provides insights into the behavior of excitons in moiré superlattices, with implications for the development of new quantum materials and devices.A team of researchers from UC Berkeley and other institutions observed moiré excitons in nearly aligned WSe₂/WS₂ heterostructures. Moiré excitons are novel excited states that emerge in two-dimensional materials due to the periodic potential created by the moiré superlattice formed when two atomically thin layers are twisted at a specific angle. The study reports the first experimental observation of these excitons in WSe₂/WS₂ heterostructures, where the moiré potential is much stronger than the exciton kinetic energy, leading to multiple flat exciton minibands. These excitons exhibit distinct gate-dependent behaviors, different from those in WSe₂ monolayers or large-twist-angle heterostructures. The findings suggest that moiré superlattices can be used to explore and control exotic excited states, such as topological excitons and a correlated exciton Hubbard model, in transition metal dichalcogenides. The research highlights the potential of moiré superlattices to engineer novel quantum phenomena in 2D heterostructures, offering a platform for studying strongly correlated electron systems. The study was published in Nature and provides insights into the behavior of excitons in moiré superlattices, with implications for the development of new quantum materials and devices.