Decoherence-Free Qubit and Chiral Emission from a Giant Molecule in Waveguide QED
Abstract
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.
Keywords
Cite
@article{arxiv.2603.27443,
title = {Decoherence-Free Qubit and Chiral Emission from a Giant Molecule in Waveguide QED},
author = {Yang Wang and Juan José García-Ripoll and Alan C. Santos},
journal= {arXiv preprint arXiv:2603.27443},
year = {2026}
}