Photonic state engineering via energy-level crossing by giant atoms in topological waveguide QED setup

Quantum Physics [Submitted on 16 Apr 2026] Photonic state engineering via energy-level crossing by giant atoms in topological waveguide QED setup Mingzhu Weng, Gang Wang, Zhihai Wang Photonic state engineering in waveguide QED is typically based on local light-matter interactions. This limits its control over the spatial structure of bound photonic states. Here, we demonstrate a distinct mechanism arising from the interplay between nonlocal giant-atom coupling and topological band structure. Specifically, we consider giant atoms coupled to a Su-Schrieffer-Heeger waveguide and show that this configuration enables a controllable energy-level crossing protected by the topological gap. Adiabatically sweeping the atomic detuning across the crossing leads to a controlled exchange between distinct photonic bound states. In a two-giant-atom configuration, this mechanism achieves high-fidelity conversion of a spatially splitting state into a combining state. Extending this scheme to three-giant atoms, we further realize robust, shape-preserving photon transfer mediated by sequential in-gap crossings. Our results demonstrate how topology and nonlocal light-matter coupling can be combined to achieve programmable control of bound photonic states in waveguide QED platforms. Comments: 7 Pages, 5 Figures, Comments are welcomed Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2604.14660 [quant-ph]   (or arXiv:2604.14660v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.14660 Focus to learn more Submission history From: Mingzhu Weng [view email] [v1] Thu, 16 Apr 2026 06:15:27 UTC (971 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)