Non-Abelian lattice gauge fields in photonic synthetic frequency dimensions

• 成果类型: Article
• 署名作者: Cheng, Dali; Wang, Kai; Roques-Carmes, Charles; Lustig, Eran; Long, Olivia Y.; Wang, Heming; Fan, Shanhui
• 署名单位: Stanford University; Stanford University; McGill University; Stanford University
• 刊物名称: Nature
• ISSN/ISSBN: 0028-1298
• DOI: 10.1038/s41586-024-08259-2
• 发表日期: 2025-01-02
• 关键词: dirac fermions; spin

摘要

Non-Abelian gauge fields1 provide a conceptual framework to describe particles having spins, underlying many phenomena in electrodynamics, condensed-matter physics2,3 and particle physics4,5. Lattice models6 of non-Abelian gauge fields allow us to understand their physical implications in extended systems. The theoretical importance of non-Abelian lattice gauge fields motivates their experimental synthesis and explorations7, 8-9. Photons are fundamental particles for which artificial gauge fields can be synthesized10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29-30, yet the demonstration of non-Abelian lattice gauge fields for photons has not been achieved. Here we demonstrate SU(2) lattice gauge fields for photons in the synthetic frequency dimensions31,32, a playground to study lattice physics in a scalable and programmable way. In our lattice model, we theoretically observe that homogeneous non-Abelian lattice gauge potentials induce Dirac cones at time-reversal-invariant momenta in the Brillouin zone. We experimentally confirm the presence of non-Abelian lattice gauge fields by two signatures: linear band crossings at the Dirac cones, and the associated direction reversal of eigenstate trajectories. We further demonstrate a non-Abelian scalar lattice gauge potential that lifts the degeneracies of the Dirac cones. Our results highlight the implications of non-Abelian lattice gauge fields in topological physics, and provide a starting point for demonstrations of emerging non-Abelian physics in the photonic synthetic dimensions. Our results may also benefit photonic technologies by providing controls of photon spins and pseudo-spins in topologically non-trivial ways33.