First-principles investigation of Er-doped CeO₂ as a solid-state spin qubit platform

Cluster correlation expansion (CCE) predictions suggest that spin defects in oxides may possess long coherence times. These findings point at the potential of designing new defects and hosts for novel quantum applications¹. In fact, a model electron-spin defect in CeO₂ has been predicted to have a coherence time of 47 ms; but the specific defect is unknown. Here we investigate the Er³⁺ dopant in CeO₂ as a candidate spin defect. The sharp emission line of Er³⁺ in the telecom band, the possibility of data storage in ¹⁶⁷Er nuclear spins, and the low nuclear-spin concentration of CeO₂, point toward Er³⁺:CeO₂ as a promising platform for quantum communications and memories. Using time-dependent density functional theory, many-body perturbation theory, and embedding methods, as implemented in WEST, we report the many-body electronic structure and excited-state properties of this defect. We also compute the spin coherence time using pyCCE and discuss the role of oxygen vacancies. Our ab initio protocol to investigate rare-earth dopants in oxides can be extended to fit crystal field parameters and study charge transfer in correlated oxides.



¹V.Somjit et al. arXiv: 2409.00246 2024; J.Davidsson et al. Nat Comm. 2024