Optically addressable electronic spins in polyatomic molecules are a promising platform for quantum information science with the potential to enable scalable qubit design and integration through atomistic tunability and nanoscale localization. However, optical state- and site-selection are an open challenge. Here we introduce an organo-erbium spin qubit in which narrow (MHz-scale) optical and spin transitions couple to provide high-resolution access to spin degrees of freedom with telecommunications frequency light. This spin-photon interface enables demonstration of optical spin polarization and readout that distinguishes between spin states and magnetically inequivalent sites in a molecular crystal. Operation at frequencies compatible with mature photonic and microwave devices opens a path for engineering scalable, integrated molecular spin-optical quantum technologies.
@article{arxiv.2505.17195,
title = {A high-resolution molecular spin-photon interface at telecommunications wavelengths},
author = {Leah R. Weiss and Grant T. Smith and Ryan A. Murphy and Bahman Golesorkhi and José A. Méndez Méndez and Priya Patel and Jens Niklas and Oleg G. Poluektov and Jeffrey R. Long and David D. Awschalom},
journal= {arXiv preprint arXiv:2505.17195},
year = {2025}
}