Physicists at the Massachusetts Institute of Technology (MIT) have discovered a novel Mott state in twisted graphene bilayers at the "magic angle" of 1.1 degrees. This new state of matter, characterized by strong interactions between electrons and the formation of an insulating phase, provides new insights into the physics of correlated electron systems and has potential implications for quantum information processing and other technological applications.

Graphene, a two-dimensional material made of carbon atoms arranged in a hexagonal lattice, has been the subject of intense research due to its remarkable electronic properties and potential applications in nanoelectronics. By stacking two graphene layers on top of each other and rotating them by a small angle, researchers can create a system known as twisted graphene bilayers. At a specific "magic angle" of 1.1 degrees, the electronic properties of these bilayers undergo a dramatic change, leading to the formation of correlated electron states.

In a study published in the journal Nature, the MIT team, led by Pablo Jarillo-Herrero and Yuan Cao, observed a novel Mott state in twisted graphene bilayers at the magic angle. Using a combination of electrical transport measurements and scanning tunneling microscopy, they found that the system undergoes a metal-to-insulator transition as the temperature is lowered, consistent with the formation of a Mott state. Furthermore, they observed an unusual coexistence of localized and delocalized electrons, suggesting a complex interplay of interactions in this system.

The Mott state found in twisted graphene bilayers is unlike those observed in conventional transition metal oxides, where the interactions are driven by the Coulomb repulsion between electrons localized on atomic sites. In twisted graphene, the interactions arise from the unique band structure that emerges at the magic angle, leading to a different mechanism for the formation of the Mott state.

This novel Mott state has potential implications for the development of quantum information technologies. The localized electrons in the Mott state could serve as qubits, the basic units of quantum information. Moreover, the tunability of the interactions and the electronic properties of twisted graphene bilayers by varying the twist angle, provides a versatile platform for studying correlated electron systems and quantum phenomena.

The discovery of the novel Mott state in twisted graphene bilayers at the magic angle opens up new avenues for exploration in condensed matter physics and quantum materials. Further research in this field could lead to a deeper understanding of correlated electron systems and pave the way for the development of novel quantum technologies.