近日，美国斯坦福大学的Shanhui Fan及其研究团队取得一项新进展。经过不懈努力，他们对光子合成频率维度中的非阿贝尔晶格规范场进行了研究。相关研究成果已于2025年1月1日在国际权威学术期刊《自然》上发表。

本文在合成频率维度中展示了光子的SU(2)晶格规范场，这是一个以可扩展和可编程方式研究晶格物理的平台。在该研究的晶格模型中，理论上观察到均匀的非阿贝尔晶格规范势在布里渊区的时间反演不变动量处诱导出狄拉克锥。研究人员通过两个特征实验上证实了非阿贝尔晶格规范场的存在——狄拉克锥处的线性带交叉，以及本征态轨迹的相关方向反转。

研究人员还展示了非阿贝尔标量晶格规范势，它提升了狄拉克锥的简并。这项研究结果突出了非阿贝尔晶格规范场在拓扑物理中的意义，并为在光子合成维度中展示新兴的非阿贝尔物理现象提供了起点。此外，这一结果通过以拓扑非平凡的方式控制光子自旋和赝自旋，可能有益于光子技术的发展。

据悉，非阿贝尔规范场为描述具有自旋的粒子提供了概念框架，是电动力学、凝聚态物理和粒子物理中许多现象的基础。非阿贝尔规范场的晶格模型使研究人员能够理解它们在扩展系统中的物理含义。非阿贝尔晶格规范场在理论上的重要性推动了其实验合成与探索。光子是可以合成人工规范场的基本粒子，然而，光子非阿贝尔晶格规范场的实验实现尚未达成。

附：英文原文

Title: Non-Abelian lattice gauge fields in photonic synthetic frequency dimensions

Author: Cheng, Dali, Wang, Kai, Roques-Carmes, Charles, Lustig, Eran, Long, Olivia Y., Wang, Heming, Fan, Shanhui

Issue&Volume: 2025-01-01

Abstract: Non-Abelian gauge fields provide a conceptual framework to describe particles having spins, underlying many phenomena in electrodynamics, condensed-matter physics and particle physics. Lattice models 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 explorations. Photons are fundamental particles for which artificial gauge fields can be synthesized, 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 dimensions, 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 ways.

DOI: 10.1038/s41586-024-08259-2

Source: https://www.nature.com/articles/s41586-024-08259-2