Decoherence-Free Qubit and Chiral Emission from a Giant Molecule in Waveguide QED

Quantum Physics [Submitted on 28 Mar 2026] Decoherence-Free Qubit and Chiral Emission from a Giant Molecule in Waveguide QED Yang Wang, Juan José García-Ripoll, Alan C. Santos Combining decoherence protection with directional photon emission in a single waveguide quantum electrodynamics (QED) device remains an open challenge. Here we show that an artificial giant molecule -- strongly interacting artificial atoms coupled to a photonic waveguide at multiple spatially separated points -- achieves both: a fully operational decoherence-free (DF) qubit and state-dependent chiral single-photon emission, arising from the same photon-interference mechanism. Initialization reduces to a local excitation of a single atom, universal single-qubit gates are implemented by modulating a single atomic frequency, and readout exploits state-dependent chiral emission with directionality reaching 100% and low measurement error of 1.2%. The coexistence of decoherence protection and directional emission in a single device positions giant molecules as protected chiral nodes for modular quantum networks in waveguide QED. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2603.27443 [quant-ph]   (or arXiv:2603.27443v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2603.27443 Focus to learn more Submission history From: Yang Wang [view email] [v1] Sat, 28 Mar 2026 23:22:35 UTC (1,457 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-03 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?)