Spin Decoherence Dynamics of Er^{3+} in CeO_{2} Films.

Area of Science:

• Quantum Information Science
• Materials Science
• Quantum Computing and Networking

Background:

• Scalable quantum networks require telecom-compatible spin-photon interfaces.
• Erbium ions (Er3+) offer a 1.5 μm optical transition and spin-1/2 ground state.
• Finding suitable hosts for Er3+ that allow device integration and preserve coherence is challenging.

Purpose of the Study:

• To investigate Er3+ doped cerium dioxide (CeO2) films on silicon as a potential host for quantum applications.
• To characterize the spin coherence properties of Er3+ in this material system.
• To identify decoherence mechanisms and explore strategies for extending spin coherence times.

Main Methods:

• Fabrication of Er3+:CeO2 thin films on silicon substrates.
• Electron spin resonance (ESR) spectroscopy to measure spin coherence times.
• Application of dynamical decoupling techniques to enhance coherence.
• Cluster correlation expansion (CCE) calculations to model decoherence.

Main Results:

• Demonstrated a spin coherence time of 38.8 μs for Er3+ in CeO2 films.
• Extended spin coherence to 176.4 μs using dynamical decoupling.
• Identified spectral diffusion from Er3+ spin flip-flops as the primary decoherence source.
• Calculations confirmed the decoherence mechanism and suggested pathways to millisecond-scale coherence.

Conclusions:

• Er3+:CeO2 on silicon is a promising platform for integrated quantum devices.
• The identified decoherence mechanisms provide a roadmap for achieving longer spin coherence.
• This work advances the development of scalable quantum networks utilizing telecom-compatible spin qubits.