Subkilohertz optical homogeneous linewidth and dephasing mechanisms in Er3+ : Y2O3

Rare-earth dopants in solids are conducive of sharp optical transitions and long spin coherence at cryogenic temperatures. While superb coherences are routine in high-quality bulk crystals, the more versatile materials such as rare-earth doped nanoparticles and ceramics have suffered from excessive decoherence due to disorder. This work reports a surprisingly narrow linewidth of Er in Y${}_{2}$O${}_{3}$ ceramics made with industry-standard synthesis technique, putting it on par with the best single crystalline counterpart. The ultranarrow linewidth also helps clarify decoherence pathways within the matrix.