Developing telecom-compatible spin-photon interfaces is essential towards scalable quantum networks. Erbium ions (Er3+) exhibit a unique combination of a telecom (1.5 μm) optical transition and an effective spin-1/2 ground state, but identifying a host that enables heterogeneous device integration while preserving long optical and spin coherence remains an open challenge. We explore a new platform of Er3+:CeO2 films on silicon, offering low nuclear spin density and the potential for on-chip integration. We demonstrate a 38.8 μs spin coherence, which can be extended to 176.4\nobreakspace μs with dynamical decoupling. Pairing experiments with cluster correlation expansion calculations, we identify spectral diffusion-induced Er3+ spin flips as the dominant decoherence mechanism and provide pathways to millisecond-scale coherence.
@article{arxiv.2508.12429,
title = {Spin decoherence dynamics of Er$^{3+}$ in CeO$_2$ film},
author = {Sagar Kumar Seth and Jonah Nagura and Vrindaa Somjit and Aneesh Bapat and Xinhao Li and Gregory D. Grant and Ignas Masiulionis and Xu Han and F. Joseph Heremans and Giulia Galli and David D. Awschalom and Supratik Guha and Jiefei Zhang},
journal= {arXiv preprint arXiv:2508.12429},
year = {2025}
}