Exploring Quantum Geometry with Terahertz Light: A Breakthrough in Twisted Bilayer Graphene
A recent groundbreaking study led by ICFO researchers, in collaboration with several international research groups, has uncovered previously unseen behaviors in magic-angle twisted bilayer graphene using terahertz light. As part of this international effort, the research sheds new light on the quantum geometry of this enigmatic material, revealing how the electronic wavefunctions of electrons are shaped by their environment. Researchers, including members from PGI-9 (Stampfer Group), contributed to this work by exploring how terahertz light interacts with twisted bilayer graphene at a level never before observed in quantum transport experiments. By utilizing terahertz light instead of traditional mid-infrared sources, the team uncovered anomalies in electron behavior, even in high-temperature conditions that typically obscure exotic quantum phenomena.
Die Ergebnisse unterstreichen die Bedeutung der Quantengeometrie - der Form und Struktur der Wellenfunktion eines Elektrons -, die die elektronischen Eigenschaften des Materials maßgeblich beeinflusst. Durch polarisationsaufgelöste Messungen des durch Terahertz-Licht erzeugten Fotostroms konnten die Forscher direkt untersuchen, wie Elektronenwechselwirkungen die Quantengeometrie des Graphen-Gitters umgestalten. Die Ergebnisse enthüllten bisher verborgene Phänomene wie Energielücken zwischen Elektronenzuständen, die für das Verständnis topologischer Phasen und der Supraleitung in Quantenmaterialien entscheidend sind.
More Information about the research
Publikation: Krishna Kumar, R., Li, G., Bertini, R. et al. Terahertz photocurrent probe of quantum geometry and interactions in magic-angle twisted bilayer graphene. Nat. Mater. (2025).
DOI: https://doi.org/10.1038/s41563-025-02180-3