Inhomogeneous and homogeneous linewidth are reported in a Eu3+ doped transparent Y2O3 ceramic for the 7F 0-5D0 transition, using high-resolution coherent spectroscopy. The 8.7-GHz inhomogeneous linewidth is close to that of single crystals, as is the 59-kHz homogeneous linewidth at 3 K (T2 = 5.4 μs). The homogeneous linewidth exhibits a temperature dependence that is typical of a crystalline environment, and additional dephasing observed in the ceramic is attributed to magnetic impurities or defects introduced during the synthesis process. The absence of Eu3+segregation at the grain boundaries, evidenced through confocal microfluorescence, further indicates that the majority of Eu3+ions in the ceramic experience an environment comparable to a single crystal. The obtained results suggest that ceramic materials can be competitive with single crystals for applications in quantum information and spectral hole burning devices, beyond their current applications in lasers and scintillatorsThis work was supported by National Science Foundation under award No. PHY-1212462, the European Union FP7 project QuRep (247743), the Spanish Ministry of Economy
and Competitiveness (MAT2010-17443) and Comunidad de Madrid (S-2009/MAT-1756
