Reconfigurable Chiral Edge States in Synthetic Dimensions on an Integrated Photonic Chip.

Chiral edge states are a hallmark of topological physics, and the emergence of synthetic dimensions has provided ideal platforms for investigating chiral topology while overcoming the limitations of real space. Conventional studies have primarily concentrated on symmetric chiral behaviors, limited by complex and inflexible systems. Here, we demonstrate a programmable integrated photonic platform to generate and manipulate reconfigurable chiral edge states in synthetic dimensions within a single lithium niobate microring resonator. Our system is realized by integrating independent frequency and pseudospin degrees of freedom in the dynamically modulated resonator, which features tunable artificial gauge potentials and long-range couplings. We demonstrate a variety of reconfigurable chiral behaviors in synthetic dimensions, including the realization and frustration of chiral edge states in a synthetic Hall ladder, the generation of imbalanced chiral edge currents, and the regulation of chiral behaviors among chirality, single-pseudospin enhancement, and complete suppression. This work paves the way for exploring chiral edge states in high-dimensional synthetic space on a programmable photonic chip, showing promising potential for applications in optical communications, quantum simulations, signal processing, and photonic neuromorphic computing.