Spin decoherence dynamics of Er$^{3+}$ in CeO$_2$ film

TL;DR

This study investigates Er$^{3+}$ ions in CeO$_2$ films on silicon, demonstrating long spin coherence times suitable for quantum networks, and identifies spectral diffusion as the main decoherence mechanism.

Contribution

It introduces Er$^{3+}$:CeO$_2$ films as a promising platform for telecom-compatible quantum interfaces with extended coherence times.

Findings

Achieved 38.8 μs spin coherence time, extendable to 176.4 μs with dynamical decoupling.

Spectral diffusion-induced Er$^{3+}$ spin flips are identified as the main decoherence source.

Pathways to millisecond-scale coherence are suggested.

Abstract

Developing telecom-compatible spin-photon interfaces is essential towards scalable quantum networks. Erbium ions (Er$^{3+}$) exhibit a unique combination of a telecom (1.5 $\mu$m) 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 Er$^{3+}$:CeO$_2$ films on silicon, offering low nuclear spin density and the potential for on-chip integration. We demonstrate a 38.8 $\mu$s spin coherence, which can be extended to 176.4\nobreakspace $\mu$s with dynamical decoupling. Pairing experiments with cluster correlation expansion calculations, we identify spectral diffusion-induced Er$^{3+}$ spin flips as the dominant decoherence mechanism and provide pathways to millisecond-scale coherence.